XI B R.AR.Y OF THE UNIVERSITY Of ILLINOIS SZ8 I£65c »v>. 4-8-50 ENGINEERING KMEERHG IMARY The person charging this material is re- sponsible for its return on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library : ■< '4 1HTERUBRARY ^W*"* LOAN L161— O-1096 Digitized by the Internet Archive in 2013 http://archive.org/details/fateofzincinnatu49ocon |#UI nnns NGINEERING STUDIES Y ENGINEERING SERIES NO 49 ENGINEERING LIBRARY UNIVERSITY OF ILLINOIS URBANA, ILLINOIS 61801 MNfffia/CE ROOM FATE OF ZINC IN NATURAL SURFACE WATERS By JOHN T. O'CONNOR Supported by DIVISION OF BIOLOGY AND MEDICINE U.S. ATOMIC ENERGY COMMISSION RESEARCH CONTRACT AT (11-1) 1264 DEPARTMENT OF CIVIL ENGINEERING UNIVERSITY OF ILLINOIS URBANA, ILLINOIS OCTOBER 1968 FINAL REPORT Fate of Zinc in Natural Surface Waters by John T. O'Connor Supported by Division of Biology and Medicine U. S. Atomic Energy Commission Research Contract AT (11-1) 1264 Department of Civil Engineering University of Illinois Urbana, Illinois October, 1968 Contents page Review of the Studies 1 Introduction: Nature of the Problem 6 Summaries of the Research Investigations 12 I. Columbia River Studies 12 1. Introduction 12 2. Analytical Procedure 22 3. Sampling Survey 29 4. Results of Analysis 34 5. Discussion of Results 41 References 52 II. Zinc Adsorption by Sediments in a Saline Environment . 55 1. Introduction .... 55 2. Survey of the Literature 56 3. Laboratory Experiments 63 4. Discussion of Results 79 5. References 81 III. Fate of Zinc in a Small Stream 84 IV. Effect of Organic Materials, Phosphates, Time and Algae on Zinc Adsorption 94 V. Effect of Reducing Conditions on Zinc Adsorption .... 104 Appendix I: Summary of Data on the Occurrence of Stable and Radioactive Zinc in the Aquatic and Terrential Environments AI-1 Final Report Contract No. AT (11-1) 1264 FATE OF ZINC IN NATURAL SURFACE WATERS Review of the Studies 1. Columbia River Studies (I) Studies of the fate of zinc in natural waters began in 1962 with a survey of analytic techniques for the separation and analysis of zinc and cobalt in environmental samples of water, bottom sediments, and plankton. Cobalt was included in this study since cobalt was separated from environ- mental samples along with zinc. Samples of water, plankton, and bottom sediments were obtained during the summer of 1963 from the Columbia River over a reach of approxi- mately 100 miles extending from just upstream of all of the Hanford reac- tors downstream to the junction of the Umatilla River with the Columbia River. The analytic procedures selected for zinc and cobalt were used for determining the quantities of both total and radioactive zinc and co- balt in the environmental samples from the Columbia River. 2. Literature Review At the time of the Columbia River studies an extensive literature review was made. All of the published data on the occurrence of stable and radioactive zinc and cobalt were tabulated to serve as a comparison with the values obtained during the current study. Most of the data appearing in the tabulation were the results of analyses made on samples taken from the Columbia River region, the Thames River, Connecticut, and the South- West Pacific area. Samples included water, fish, farm produce, sewage, sediments, plankton, invertebrates, insect larvae, birds, animals, man, etc. The tabulation of data was appended to Report I. Watson, Robert H. "A Survey of Radioactive Zinc and Cobalt in the Columbia River," Civil Engineering Studies, Sanitary Engineering Series No. 25, University of Illinois, January 1965- C00-1264-2 3- Effect of Salinity on Zinc Adsorption (II) Laboratory studies were conducted to determine the effect of increasing salinity on the zinc-sediment equilibrium. These studies at- tempted to simulate the emptying of a river into an estuary and to de- termine what effect the increased salinity and increased dilution had on the quantity of zinc found in solution in equilibrium with suspended sedi- ment. 4. Preliminary Stream Study (III) A preliminary field study of zinc transport and equilibrium in a stream was conducted during the summer of 1964. Stream flows were mea- sured and the time of flow between sample stations was determined by chlo- ride tracer studies. Zinc chloride was then discharged to the stream to obtain a zinc concentration of approximately 5 mg/1 in the stream. Samples were taken at locations downstream of the point of discharge. Following the discharge of zinc chloride by about an hour, hydrochloric acid was discharged to the stream to lower the pH of the stream. Throughout the period of zinc chloride and hydrochloric acid i discharges, measurements of pH were made and samples were taken for sub- ■ sequent analysis for zinc. In addition, sediment samples were collected ! in Petri dishes buried in the sediment prior to the start of the study. I 5- Stream Study (1965) (IV) The preliminary stream study conducted in 1964 was the prelude to a larger scale stream study made in the summer of 1965- A longer reach | of the same stream was selected and preparations for sampling water, mud I and bottom organisms were made in a manner similar to those made for the | preliminary study. A weir was constructed in the stream bed for flow ! H " Sonnen, Michael B. "Zinc Adsorption by Sediments in a Saline Environment," Civil Engineering Studies, Sanitary Engineering Series No. 24, University of Illinois, January 1965- C00-1264-1. III_ . Davis, Mackenzie L. "The Fate of Zinc in a Small Stream," Civil Engineer- ing Studies, Sanitary Engineering Series No. 27, University of Illinois, June 1965. C00-1 264-3. IV Results were presented at the 152nd National Meeting of the American Chemi- cal Society, Division of Water, Air, and Waste Chemistry, September 11-16, 1966, New York, New York. easurement. Planks were placed and anchored at each sampling station o facilitate sample collection. Zinc chloride solution was prepared in ulk so that the discharge of zinc to the stream could continue for 12 ours. Laboratory preparations were made to receive samples from seven ampling stations hourly. Samples were analyzed for pH and alkalinity iimediately upon collection. Two aliquots of the sample were taken for ubsequent zinc analysis; one was filtered through a membrane filter so hat "zinc in solution" could be determined, the other aliquot was for otal zinc. At four hour intervals, bottom sediment samples were col- ected so that the amount of zinc adsorbed or deposited on the sediment ould be determined. In addition, the number of bottom organisms in the ediments were enumerated. The sampling program continued for approximately one and a half ays. A crew of five worked continuously for 2k hours while samples were eing collected hourly. Thereafter, samples were collected every two ours. In all, some six hundred samples were collected for zinc analysis. y the end of September 1 965 > the analysis of all samples for zinc had been ompleted. 6. Effect of Organic Materials on Zinc Adsorption (V) Studies were made to determine the effect of soluble natural or- anic materials extracted from Illinois ground waters on the adsorption f zinc by sediments obtained from the Columbia River at Hanford, ashington. The natural organic materials were extracted from several housand gallons of Oakwood, Illinois, ground water on a series of acti- ated carbon columns. 7- Effect of Reducing Conditions on Zinc Adsorption (VI) Reducing conditions reportedly lead to the release of adsorbed inc from bottom sediments. The shift in the zinc equilibrium is due, n part, to a lowered pH resulting from CCL production under anaerobic Results were presented at the 1 6th Annual Conference, American Institute of Biological Sciences, August 15-20, 1965, Urbana, Illinois. leckman, Jerold W., "Zinc Adsorption by Precipitated Iron on Lake Bottoms," [Civil Engineering Studies, Sanitary Engineering Series No. 37» University =>f Illinois, June 1966, C00-1264-4. onditions. From theoretical considerations, the shift in equilibrium ould be expected to be independent of the dissolved oxygen concentra- ion and the oxidation-reduction potential. However, the return of pre- ipitated ferric oxides to solution under reducing conditions will reduce he adsorptive capacity of bottom sediments and result in the release of ther cations to solution. This condition would apply more frequently to akes than to streams. This phenomena was observed and studied in a laboratory unit hich simulated conditions in a stratified lake. 8. Basic Chemistry of Zinc The relative insolubility of the salts, zinc carbonate and inc hydroxide, normally place an upper limit on the quantities of zinc ound in natural waters. In some natural waters, however, the solubil- ty may exceed the values computed from solubility products owing to the ormation of inorganic complexes of chloride, ammonia, and cyanide with inc. The influence of the presence of ligands which alter the solu- ility of zinc have been estimated from chemical equilibria. Calcula- ions indicate that the concentrations of chloride, ammonia, and cyanide ound in natural waters do not have a significant affect on the quantity f zinc found in natural waters. 9- Increase in Zinc Adsorption with Time In studies of zinc adsorption, emphasis has been placed on the mmediate uptake of zinc which is essentially complete within a few minutes o determine whether adsorption characteristics change over longer periods f time, sediment-water samples containing zinc were stored for 20 days, n initial zinc adsorption versus pH curve was measured for reference. he observed results were taken as an indication that a zinc precipitate as slowly being formed at neutral pH values. Such precipitation might, in some cases, lead to the erroneous conclusion that an increase in ad- aptive capacity takes place over a prolonged period of time. 10. Zinc Uptake by Algae Various investigators have been concerned with the mechanism f zinc uptake by algae. In particular, they sought to determine whether ptake was primarily related to metabolic processes or due to adsorption. review of this work was conducted to provide a background for comparisons f the relative importance of adsorption on sediments as compared with ad- emption or uptake by algae. production: The Nature of the Problem Studies have been conducted to determine the effect of dis- larging small quantities of zinc to natural waters. Interest in this ;tal has intensified following the discovery that the isotope, zinc-65, in accumulate in fish, mollusks, algae and the human body . Low con- ;ntrations of zinc-65 tend to concentrate in aquatic organisms, parti- ilarly in brackish water and marine shellfish. This isotope has there- ire been found in the bodies of people who feed on seafood harvested •om areas where heavy fallout from nuclear testing has occurred . 2 3 nc-65 has also been found in reactor and cyclotron workers. Although zinc-65 is not a fission product, it is frequently >und in greater abundance than any single fission product in marine or- k snisms . A variety of foods in the United States, chiefly oysters and ams, have been found to contain small amounts of radio-zinc. Zinc-65 )s been found in foods irrigated with water from the Columbia River be- )w the Hanford station . At one time, marked increases were noted in ie zinc-65 content of oysters harvested from the Thames River (Connecticut) :ar a nuclear submarine base . Recently an inventory of radionuclides :posited in the Columbia River between Pasco and Vancouver, Washington idicated that over 8000 curies of zinc-65 were associated with the river )ttom material s as of January 1965 • These observations have stimulated iterest in the zinc system in natural waters since the behavior of radio- :tive zinc in rivers, lakes and estuaries is determined by the much more )undant stable zinc in these waters. Prior to 1950, little attention was paid to zinc in natural aters except in studies of toxicity to fish. For one thing, zinc has 3 special public health significance. Secondly, the analytic procedures )r zinc were inaccurate and time-consuming. Most important, the quanti- ses of zinc found in natural waters free from mine drainage and industrial o astes are very low, normally well under 100 u.g/1 . Even where zinc wastes re discharged into natural water courses, zinc disappears rapidly from ^lution at points downstream from the point of discharge. River silts 9 "i such areas have high zinc contents . hemistry of Zinc in Natural Waters The relative insolubility of the salts, zinc carbonate and inc hydroxide, place an upper limit on the quantities of zinc in solu- ion in natural waters. The solubility restrictions on zinc, however, o not often determine the quantity of zinc found in natural waters. ost often, the concentrations of zinc found in natural waters are about M, several orders of magnitude below calculated solubility limits. espite conditions of undersaturat ion, the concentrations of zinc found o n natural waters have been found to decrease with increasing pH . This as been attributed to the increased adsorption of zinc ion on sediments t higher pH. The redox chemistry of zinc is simple, since zinc forms com- ounds only in the +2 oxidation state. Moreover, despite the ability of inc to form hydroxo, chloro, cyano, ammine and organic complexes, the redominant form of zinc found in natural waters is the tetraaquo zinc Dn, Zn(hLO), . Even in sea-water the hydrated zinc ion is predominant lthough the mono-, di-, tri-, and tetrachloro complexes will form to a ignificant extent. With increasing pH, the monohydroxo zinc ion, In(H ? 0) OH] will also form, but its relative abundance will not be nportant until pH 8.5 is exceeded. No thermodynamic data is available for the formation of a pre- ipitate or si 1 icato-zinc complex, such as Zn(SiO(OH) ,) „ • However, some a misinterpretation of the results of adsorption studies where the mcentration of zinc in filtered samples is used to compute the quantity zinc which was presumably adsorbed on clays. mcentrations of Zinc in Natural Waters Information on the concentration of zinc found in solution in itural waters is limited and unreliable. Frequently, for example, nc concentrations have been recorded as nil if they did not approach e limit (15 mg/1 Zn) set for zinc in the 19^6 U.S. Public Health Service ■ecommended drinking water standards . In addition, errors due to improper ;ampling techniques, precipitation during storage, loss of zinc during :ransfer and filtration, insensitive analytic techniques, and contamina- :ion of glassware, have led to unreliable data. However, the range of 'inc concentrations reported in natural fresh waters, excluding streams _o c -eceiving drainage from mines, is from 10 to 3 x 10 H or approximately I to 200 u.g/1 as zinc. The zinc concentrations found in oceanic and zoastal waters are of the order of 10~ 7 M, (5-10 u.g/1 Zn) . There appears to be a rapid depletion of zinc from solution when fresh waters join jceanic waters. This may be partly due to increased adsorption due to increased pH, to coprecipitation of zinc with calcium carbonate, to up- take by marine organisms or to the incorporation of zinc in precipitated narine sediments. A summary of some reported values of the concentrations of zinc in natural waters is given in Table 1. Table 1 Zinc Concentrations in Natural Waters iiraidech and Emery (1935) '.ehoe and Cholak (1944) 12 ISPHS (195^) 13 jleinkopf (1955, I960) 14 11 16 jorita (1955) 15 utchinson (1957) |cConnell (1957) 1? oyle (1958) 18 iprague (1961-1964) 19 22 • prague ( 1 964) 20 jrum and Haffty (1963) jivingstone (1963) J 1 Connor ( 1 964) 8 /erdrup (1942) •umholz (1957) 21 (Range) (5-300) (10-130) (0.3-34) (1-18) (5-300) (58-200) (1-20) (0-215) (10-200) 23 24 lipman (1958) 30 56 136 2.5 7-7 62 20 25 3.3 10 5 10 10.6 26 )U gis (1961) irum and Hafftv (1963) 21 (1-30) («S-10) Avg. Zn Concentrations, u.g/1 Surface waters, U.S. water supplies) U.S. drinking waters) Columbia River) Maine lakes) Japanese lakes and ponds) U.S. waters) Bear Lake, Idaho) streams, southwestern Nova Scotia) annual averages, polluted section, Miramichi River, Canada) Northwest Miramichi River, Canada) North American rivers) Lake and river waters, U.S.) Rivers, Chesapeake Bay region) oceans) seawater) coastal waters, Atlantic and Gulf of Mexico) seawater) seawater) istribution of Zinc in Environmental Samples The distribution of radioactive zinc 65 in environmental samples s determined by the distribution of the far more abundant stable zinc, n sediment-water systems, the distribution of zinc is primarily influ- nced by exchange on electrostatic sites, precipitation and chelation. The ffect of chelation is felt to be relatively small . In addition, dsorption takes place on the surface of the hydrous oxides of iron and anganese. In studies using radioactive zinc 65 various alga, plankton, nd molluscs have been found capable of accumulating zinc from fresh and 29 30 ea-waters ' . Uptake of zinc from sea-water has often been found o be rapid and nearly complete. While some alga will retain the zinc, nimals (sea-fish, molluscs) may release it to pure sea-water within a 31 atter of days Concentration factors are frequently cited to illustrate the bility of organisms to concentrate zinc over the concentration present n water. The value of computing concentration factors when the absolute esidual concentration of the element in the aqueous phase is infinitesimal 1 y mall and, in fact, cannot be analytically determined with any reasonable egree of accuracy is open to question. Moreover, this practice may in- rease the tendency to overlook other factors which markedly influence inc equi 1 ibria. 3 4 For zinc, concentration factors are often as high as 10 to 10 . 33 able 2 is abstracted from data compiled by Polikarpov Table 2 Zinc Concentration Factors in Marine Organisms (approximate averages, after Polikarpov) 3 Brown algae 10 3 Coel enterates 10 Crustaceans 10 1+ Molluscs 10 Fish 3 x 10 3 10 In molluscs, zinc is found primarily in the soft tissues (gills, 34 nantle, visceral organs) . Little is found in the shell. Zinc is also found concentrated in the visceral organs (liver, spleen, heart, ddneys, pancreas and alimentary canal) of sea-fish. Despite lower con- :entrations, the muscles of the fish are found to contain the bulk of 31 the zinc, since the muscles comprise 90% of the fish by weight " . Radioactive Zinc-65 in Environmental Samples Radioactive zinc-65 is found primarily in discharges of cooling waters from nuclear reactors. In the United States, the greatest discharge of zinc-65 has taken place from the Hanford Works to the Columbia River in Washington. Table 3 shows the approximate average amounts of radioactive zinc-65 found in various samples collected in the Columbia River region. \ more detailed tabulation of such data is presented in the Appendix I: Summary of Data on the Occurrence of Stable and Radioactive Zinc and Cobalt in the Aquatic and Terrestial Environments. Table 3 Zinc-65 in Samples Collected in the Columbia River Region, pc/g River water 0. 1 - 0.5 River sediments 1000 Freshwater fish 20 - 100 Grass, foods 0.1 - 1.0 Sea water .0002 Marine sediments 10 Oysters, clams 70 Algae, plankton, larvae 100 - 1000 The maximum permissible concentrations (MPC) which have been adopted for zinc-65 are summarized in Table k. A comparison with the ,'eported values in Table 3 would indicate that the concentrations of ;'.inc-65 in river waters may be well below the MPC values, but that the oncentrations found in aquatic organisms may be close to the recommended imits in regions receiving discharges from nuclear power plants. 11 Table 4 MPC for Man of Zinc-65 in Water and Marine Organisms (after Polikarpov) Zinc-65, pc/1 C.F pc/g 5 Drinking water (U.S. standard) 10 Drinking water (Soviet standard) 10 Sea water (U.S.) 400 Marine organisms 5000 Edible marine organisms 10 I. COLUMBIA RIVER STUDIES 12 1. INTRODUCTION HE HANFORD REACTORS AND THE COLUMBIA RIVER The Hanford Atomic Products Operation, or the Hanford Works, is ocated in a United States Atomic Energy Commission reservation in the outheastern section of the State of Washington, as shown in Figs, 1.1 and ,2, The reservation includes an area of about five hundred square miles, lant operations commenced in 1944 and have expanded to the present complex hich includes eight production reactors, fuel fabrication plants, chemical eparation facilities and research and development laboratories. In 1963, the installation was operated for the Atomic Energy Commission by the General lectric Company, The Columbia River flows through the reservation and orms part of its eastern boundary. The part of Washington in which Hanford Works is located is emiarid, having an average annual rainfall of about eight inches, and thus rovides an excellent site for nuclear reactor operation. The inclusion f the Columbia River within the reservation is also advantageous , as it as a minimum flow of about 50,000 cubic feet per second at Hanford. This onsiderable minimum flow provides both a continuous source of reactor ooling water and also a means of disposing, by dilution, of large quant i- ies of low-level radioactive wastes, Columbia River water has been used as a source of reactor cooling ater since the start of operations in 1944, Water is pumped from the iver and passes through a complete water treatment plant which includes coagulation, sedimentation, filtration and chlorination. Chromates are idded to the water to keep corrosion to a minimum. The effluent from the reatrnent plant is maintained at less than .01 units of turbidity. The cooling water passes once through a reactor and then into an open retention fig. 1.1 GEOGRAPHICAL RELATIONSHIP OF KAN FORD WORKS TO PACIFIC NORTHWEST fig. 1.2 ■ HANi )] D i "V )J£CT Mil ' 15 tank where short-lived isotopes are allowed to decay before the water is returned to the Columbia River , The Columbia River, as shown in Fig„ 1,3, has a flow at Pasco, Washington, ranging from 60,000 to more than 300,000 cubic feet per second. The flow at Hanford is slightly less, as the Yakima River joins the Columbia between these two locations , The flow past Hanford is rapid. The river water is of excellent quality, having a pH of between 7,5 and 9,0 with an average of 8,1, an alkalinity of between 43 and 170 mg/1 with an average of 65 mg/1, and a very low turbidity , As the river passes Richland, Washington, it enters the reservoir formed by McNary dam, and the current velocity decreases. Sediments have been accumulating slowly in the impound- ment since it was placed in operation in 1953, In late summer and early fall, the water contains approximately 1 mg/1 dry weight of organic matter. The organic matter is composed mainly of phytoplankton , with diatoms making up over 90 percent of the population and the Cyclotella diatoms predominant during this period of the year, ENVIRONMENTAL RADIATION EXPOSURE AND MONITORING IN THE HANFORD AREA A fraction of the impurities remaining in the cooling water, after treatment, is transformed into radioactive elements during passage through the reactor and during retention in films which form on the surface of the fuel channels and elements. The majority of the radionuclides are thus formed by neutron activation rather than by fission. As the reactor effluent re en Oil ci 9^Q rfater enters the Columbia River, it contains: Mn , Cu , Na , Cr , Np v ' , . 76 „.31 *s , Si , making up 90 percent of the total radioactivity; 13 other radio- fit: nuclides, including Zn , which make up 8 percent of the radioactivity; and fin >ver 40 others, including Co , which make up the remaining 2 percent of ..-< 1958 1959 1960 1961 1962 1963 ZINC 65 IN COLUMBIA RIVER WATER AT PASCO, WASHINGTON 17 the radioactivity. It should be noted that Zn ' is of minor importance and 60 Co only a trace radionuclide as the reactor effluent enters the Columbia River. The extensive monitoring program at Hanford and downstream in the Columbia River has shown that natural background and world-wide fallout are the primary sources of environmental radiation exposure for most persons in the neighborhood of the Hanford reservation. The principal Hanford source of environmental exposure has been identified with the neutron in- duced radionuclides present in reactor cooling water discharged to the Columbia River, The primary mechanisms of exposure from this source are the drinking of water derived from the river and the consumption of fish and water fowl which inhabit the river. Consumption of products from farms irrigated with Columbia River water provides an additional source of exposure , The composite annual exposure for a hypothetical individual whose habits include consumption of locally caught fish, consumption of products from farms irrigated with Columbia River water, consumption of water from the Pasco sanitary system (which is derived from the Columbia River), and iwho engage in swimming and boating on the river, has been estimated at 150 mrems to the GI tract, 70 mrems to the total body, and 30 percent of the National Committee on Radiation Protection (NCRP) maximum permissible j ;?ate of intake for bone seeking radionuclides. A high rate of consumption if certain marine organisms, such as oysters from the Willapa Bay, Washington, area would increase the rate of intake. An extensive and continuous monitoring program developed by lanford assures the safety of the residents of Richland, Pasco and other uties along the Columbia River from overdoses of environmental radiation. ZINC 65 AND COBALT 60 65 Zinc ' constitutes only about one percent of the total radioactivity discharged into the Columbia River. Cobalt is present as a trace radio- nuclide in the reactor effluent. Neither radionuclide would appear to be a 65 potential radiation exposure hazard. However, Zinc ' has a half-life of 245 days and Cobalt has a half-life of 5.27 years. Due to their long half- lives, the activity of these radionuclides does not decrease rapidly. Only a very small percentage of the activity would have decayed during the normal flow time required to reach Pasco, Washington, about 40 river miles down- stream from the reactors. 65 The flow in the Columbia, the concentration of Zinc * in the water and the rate of transport of Zinc ' have been monitored by the Hanford staff. Data resulting from monitoring at Pasco from 1958 to 1963, is presented in 65 Fig, 1,3. The data indicate that the rate of transport of Zinc % has decreased from an annual average of about 100 curies/day in 1958 to an annual average of about 55 curies/day in 1963. 65 The annual average Zinc ' activity in the Columbia River in 1963, as reported by the Hanford staff, was ,47 pc/g at Hanford Ferry, just 'iovmstream from the reactors, .38 pc/g at Richland, ,22 pc/g at Pasco and .06 pc/g at Vancouver, Washington, which is 260 miles downstream of the 65 Reactors. These data indicate that 19 percent of the Zinc * activity was removed from the water by the time it reached Richland, 47 percent had been removed by the time it reached Pasco and 87 percent by the time it reached I, ancouver. Other studies by the Hanford staff have shown that the removal f Cobalt activity from the Columbia River water in this reach compares 65 losely with Zinc . Richland began using Columbia River water in 1963 and 65 las able to remove an average of 80 percent of the Zinc ' activity of the jiver water in its water treatment plant. Pasco, which has been using 19 Columbia River water for many years , removes about 60 percent of the Zinc activity of the river water in its treatment plant. The Hanford staff have concluded that Zinc ' is removed along with particulate matter. The radionuclides may initially come in contact with suspended particulate matter, or bottom sediments, or a combination of these o Most of the suspended particulate matter eventually settles, with the finer particles being carried as far downstream as McNary reservoir. The high degree of removal by the water treatment plants of Richland and Pasco further indicates an affinity between the particulate , 65 matter and Zinc . Some forms of biota, such as certain algae, have been shown to 65 concentrate Zinc ' thousands of times over the concentration found in the surrounding water. Whitefish caught between the reactor area and Pasco c c contained an average Zinc concentration of 38 pc/g wet weight, in 1963, or more than one hundred times the concentration of Zinc ' in the sur- rounding water. However, the biota is sparse in this section of the Columbia River. The accumulation by the biota can thus account for only a 65 minor fraction of the depletion of Zinc in this reach. The Hanford staff analyzed five bottom sediment samples taken along the shorelines of the Columbia River in the reach extending from Ringold to Richland, in March, 1962. A sample from the river bank opposite Ringold contained 310 pc/g of Zinc %> and 13 pc/g of Cobalt . The four remaining samples were from the shorelines of islands in the river between Ringold and Richland, The concentrations of Zinc ' and Cobalt were found to decrease with distance downstream from the Hanford reactors. Con- ge centrations of Zinc ' declined steadily from 880 to 170 pc/g, while 60 concentrations of Cobalt declined from 24 to 5,6 pc/g with the exception of one sample which contained 69 pc/g of Cobalt . All data were expressed 20 as grams dry weight of sediment Zinc w accounted for about one-third of the total activity found in these samples „ In core samples taken by the Hanford staff of the bottom sediments in McNary reservoir in 1962, Zinc ' accounted for over two-thirds of the fin total radioactivity o Cobalt was also accumulated on the bottom sediments From the average of seven core samples, it was estimated that the sediments 65 of the reservoir contained 1350 pc of Zinc per gram dry weight of sedi- ment, and *+7 pc of Cobalt per gram dry weight of sediment, at the sediment -water interface „ This concentration decreased rapidly with depth to values of about three pc/g for each radionuclide at a depth of twelve inches. It was estimated that the sediments contained a total of 57,000 pc of Zinc and 2500 pc of Cobalt per square inch of sediment, or 230 cc en curies of Zinc ' and 10 curies of Cobalt per square mile of sediment Much of the information included in this introduction has been gathered from various reports of the Hanford Environmental Studies and Evaluation staff (35,37, 38, 39 ) Other data have been gathered from a study of the Columbia River made in 1954 by the United States Public Health Service (f3).and from personal discussions with Dr Benjamin B Ewing, Professor of Sanitary Engineering, University of Illinois OBJECTIVES OF THE STUDY The overall objective of a proposed comprehensive Columbia River study is, as described by Dr Benjamin B Ewing: "to determine the fate of certain radionuclides in the Columbia River downstream of the Hanford reactors. This river offers a unique site for such a study in that radionuclides have been discharged to the river in reactor cooling water for many years. While no hazard of significance has been produced, the quan- tities of radionuclides which have been put into the river are greater than at any other site in the United States „ 21 "It is proposed that i.ne study be confined to the reaches of the river between Priest Rapids Dam (upstream from the reactors) and Vancouver, Washington o The approach is a material balance; i„e,, to compare the rate of input to any reach, corrected for decay, with the rate of output from the reach to ascertain the fraction depleted. Whenever a significant depletion is encountered, a survey will be made to locate the places of storage. Such a study will provide information about the mechanisms which remove radionuclides from river water and the factors which influence these mecha- nisms, the quantity of each radionuclide being retained in various river reaches, location, and nature of storage, the likelihood of translocation and the potential hazard arising from a possible translocation of stored radionuclides „ "The results of this study are needed to provide a better understanding of the fate of radionuclides in a river in order to permit prediction of the hazards which might result from a change of conditions in this river at some future time, or which might be encountered in other rivers under similar circum- stances o" The particular objectives of the current study were; (a) to obtain, by an extensive literature search, a knowledge of the occurrence of stable and radioactive zinc and cobalt in the aquatic and terrestrial environments and an understanding of the fate of these two elements when discharged into the aquatic environment; (b) to develop analytical techniques for determining the concen- trations in environmental samples of both the radioactive and the stable fractions of zinc and cobalt, stressing simplicity of procedure and ana- lytical equipment; (c) to obtain and analyze samples of water, plankton and partic- ularly bottom sediments , from a one-hundred-mile reach of the Columbia River between just upstream of the Hanford reactors and just downstream of McNary dam. 22 2. ANALYTICAL PROCEDURE Analytical procedures were developed for Che quantitative determination of total and radioactive zinc and cobalt in jaraples of river water, plankton and bottom sediments collected from the :olumbia River on August 14 and 15, 1963. The analysis of each sample was divided into four phases as Illustrated in Fig, 2. Phase I began with the sample as received at the Laboratory, It included preliminary separations of each sample to change it to a more suitable form for analysis. Phase II included analyses for total zinc and cobalt and total gamma radioactivity. The third phase was the separation and isolation of the elements, zinc and cobalt. In the fourth phase, the zinc and cobalt fractions were quantitatively analyzed for both radioactive and total zinc and cobalt. It should be noted that this system provided a quantitative check on the method used for separation and isolation of each of the two elements, A qualitative check was provided by comparing the waveform of the isolated samples on a single channel gamma ray spectrometer with that of standard waveforms of these two elements. Any appreciable contamination or carry- over would cause a discrepancy in the shape of the isolated sample's waveform, PHASE I Water Each water sample had been passed through a Dowex 50 hydrogen l^ycle cation exchanger at the collection site. These exchangers were sealed ;ind delivered to the laboratory. The exchangers were made up of approxi- mately 120 ml of exchange resin contained in a 150 ml columnar separatory WATER (In Dowex 50 cation resin) l Eluted with 2N-HC1 i I + ti ELUATE Concentrated by Evaporation IH PLANKTON Washed with 0.5N-HC i I t RESIDUE Dri< ed and Weighed f 23 BOTTOM SEDIMENTS Counted for Total Gamma Activity J Dried and Weighed ! Counted for Total Gamma Activity ili Counted for Total Gamma Activi ty S*- Sample Taken for Total Zinc and -„___ Correction Made Total Cobalt = ~ s " SS:S *~for Loss in Remaining Sample I 53J Zinc and Cobalt isolated by Anion Exchange Chromatography COBALT Analysed for Total Zinc Counted for Gamma Activity IV Composite Sample of Zinc i Concentrated by Evaporation Gamma Spectrum Compared with Standard Analysed for Total Cobalt ! Counted for Gamma Activity 1 Composite Sample of Cobalt 1 tntrax Concentrated by Evaporation f Gamma Spectrum Compared with Standard FLOW DIAGRAM OF ANALYTICAL PROCEDURE 24 funnel o The resin was held in place in the funnel with the aid of glass rfool plugs at each end of the funnel. When received at the laboratory, >ach exchanger was unsealed, attached to a retort stand and a 500 ml sep- aratory funnel reservoir was sealed to the ground glass inlet „ The reservoir was filled with 2N-HC1 and the acid allowed to pass through the :ation resin at a rate of approximately .5 ml/sq cm /min. Ten resin volumes of 2N-HC1 were passed through the resin. The eluate was collected in a 1000 ml volumetric flask and transferred, with washings of .5N-HC1, co a 1000 ml beaker. The glass wool filters used in the collection of rfater samples were also washed with 2N-HC1 and the washings added to the weaker. The beaker was then placed over a Bunsen flame in a hood. Three "V" shaped pieces of glass tubing were placed on the top edge of the beaker and a six-inch diameter watchglass, with its convex face pointed down, was placed on top of the glass "Vs. This method resulted in rapid evaporation without loss of sample or contamination. The eluate was evaporated to a final volume of approximately 50 ml and stored, with washings, in a gradu- ated glass bottle. The above method was used for all concentration steps in the analyses. Plankton Each plankton sample was received at the laboratory in 250 ml sealed glass bottles. Each sample was shaken, unsealed and poured, with washings of .5N-HC1, onto a ,45 p membrane filter placed over a disc of fiberglass window screening in a six-inch diameter Buchner funnel inserted kn a vacuum flask, A vacuum was applied to the flask and the sample washed pith five 100 ml aliquots of .5N-HC1. The residue was dried at 103 de- crees Centigrade and weighed to determine the initial dry weight of the plankton sample. The residue was then placed in a plastic test tube and 25 counted for total gamma activity. The eluate was concentrated to approxi- mately 50 ml by evaporation and stored, with washings, in a graduated glass bottle. Bottom Sediments Each bottom sediment sample was received in the laboratory in sealed plastic containers which held about 1500 to 2000 grams of moist sedi- ment. Each sample was thoroughly mixed on a large plexiglass plate. A 10 to 15 g dry weight representative sample was placed in a plastic test tube and counted for total gamma activity. The contents of the test tube were then placed on a glass dish, dried at 103 degrees Centigrade, and weighed. A 250 to 350 g dry weight representative sample was taken from the original sample and washed with five 200 ml aliquots of . 5N-HC1 to remove the zinc and cobalt, using the same apparatus and procedure as was used for the plankton samples. The residue was dried at 103 degrees Centi- grade for 24 hours and weighed. A 10 to 15 g sample of the dry residue was taken and counted for total gamma activity to determine what proportion of gamma activity remained after the acid wash. The eluate from the acid wash was concentrated to about 150 ml by evaporation. In this evaporation step a yellow-amber gel formed when the eluate had been concentrated to about 150 ml. Care had to be exercised at this stage, as the gel had poor heat transfer characteristics and tended to "pop," At this point the gel was cooled and refiltered, using five 100 ml aliquots of .5N-HC1 to remove the zinc and cobalt from the gel. (After this treatment, the remaining gel was white and opaque. Samples of the washed gel were counted and found to contain negligible activity.) The eluate was finally concentrated to approximately 50 ml and stored in a graduated glass bottle. 26 PHASE II At the beginning of Phase II, the zinc and cobalt separated from each sample was in an aqueous phase and concentrated to approximately 50 ml in volume. The samples were about 6N in HC1 (due to evaporation) and had been stored in graduated glass bottles. The original volume of the water samples were known. These volumes could be converted to weight for future calculations. The dry weights of the plankton and bottom sediment samples were known. All data for plankton and bottom sediments could thus be recorded in terms of dry weight* The remaining portion of each bottom sediment sample was dried and weighed in order to obtain data regarding bottom sediments in terms of the surface area of the river bottom. The initial step in Phase II was to take a 10 ml aliquot of each sample from the graduated bottles and count each aliquot for total gamma activity. This activity was recorded in terms of cpm per g of original sample. Dry weights were used throughout the analyses for plankton and bottom sediment samples. The 10 ml aliquots were then returned, with washings of . 5N-HC1, to the graduated glass bottles. Samples not exceeding 5 ml were taken for total zinc and total cobalt analyses. These analyses were to be used only as checks for gross error in the more accurate analyses performed after each element had been isolated. They were also used to provide approximate solution concentra- tions so that the samples would be within the correct range of allowable concentrations when the final analyses were made. The procedures used for these analyses are recorded at the end of this chapter. Corrections were made for the volume of sample lost in this step. Finally, 12N-HC1 was added to the remaining concentrated eluate until it was at least 7N in HC1, 27 PHASE III Fresh anion exchange columns were made up for each sample, con- structed in the same manner as the water sampling exchangers, but containing about 30 ml of resin in a 50 ml columnar separatory funnel , Dowex 1, chloride cycle, 50 or 200 mesh anion resin was used for separating and isolating and zinc and cobalt <> The flow rate through the anion exchange column was approximately ,2 ml/sq cm /rain. The following procedure was used: Procedure for Separation and Isolation of Zinc and Cobalt lo Pass three resin volumes of 7N-HC1 through 30 ml of Dowex 1 anion resin in a column. 2, Make sample at least 7N in HC1 and three resin volumes in volume and pass through resin, 3, Pass ten resin volumes of 7N-HC1 through resin as a rinse, 4, Pass ten resin volumes of 4N-HC1 through resin and collect eluate. Concentrate eluate to approximately 50 ml by evaporation and store in graduated glass bottles. This fraction contains the cobalt, pure and «*N in HClo 5 Pass ten resin volumes of >5N-HC1 through resin as a rinse, 6, Pass ten resin volumes of .01N-HC1 through resin and concen- trate as in step 4, This fraction contains the zinc, pure and ,01N in HC1, 7, Discard the used resin, PHASE IV At the beginning of Phase IV, the zinc that had been separated from the original sample had been isolated in a pure state and stored as a liquid in a graduated glass bottle in dilute HC1, The cobalt fraction was 28 in a similar condition except that the normality of the acid in which it was stored was much higher, at approximately 6N f due to evaporation » Accurate values for radioactive zinc and for radioactive cobalt could now be obtained by counting 10 ml aliquots of each sample . Accurate values for total zinc and total cobalt could also be obtained, using the procedures described at the end of this chapter and by diluting or concentrating the sample to a proper volume, as ascertained by the previous analyses, to place the concentration within the required range for analysis » A composite sample of zinc and another of cobalt were re-concentrated until their activities were great enough to run a gamma spectrum of each. This spectrum was compared with that of a standard, at the same activity level, to provide a qualitative check on the isolation procedure. ANALYSES FOR TOTAL ZINC AND FOR TOTAL COBALT The analysis for total zinc was an adaptation of the method called the "Mixed-Color Method" described on page 265 of the 11th edition of Standard Methods for the Examination of Water and Wastewater . All reagents were unchanged. The analysis for total cobalt was an adaptation of the method called "Procedure B (Citrate-Phosphate-Borate Medium)" de- scribed on page 419 of Colorimetric Determination of Traces of Metals by Eo B, Sandell (1959). All reagents were unchanged. 29 3. SAMPLING SURVEY On August 14 and 15 8 1963 B four water, four plankton and twenty- four bottom sediment samples were collected from the Columbia River 9 from a reach of the river extending from just upstream of all of the Hanford reactors downstream to the junction of the Umatilla River with the Columbia 6 a distance of 97 8 river miles The location of each of the sampling points is noted in Fig. 3. Water samples were taken to determine whether Zinc ' and Cobalt were being removed from the river water as it moved downstream 9 and if so 8 to determine how rapidly these two radionuclides were being removed 8 and where the removal was occurring. It should be noted that only four water samples were taken and that the resulting data are therefore very limited. The Hanford staff have accumulated a wealth of data concerning the analysis of water samples and have applied this data to fulfill the objectives stated above. Plankton samples were taken to ascertain the degree of concentra- tion of Zinc ' and Cobalt exhibited by these aquatic organisms s and also to show the effect of location along the river on the concentration of these radionuclides in plankton. A series of bottom sediment samples were taken in order to determine the concentration of Zinc ' and Cobalt along approximately 100 miles of the river from the reactors to below McNary dam. WATER SAMPLES Water samples were taken at 15 to 33.5 mile intervals along this reach of the Columbia River. The first two samples were taken in the late 30 iff- t f >7 >8 n i 10 ,A^ A l4 *U £ IRICHLANO PASCO $H**L 18, *i\/£* KENNEWICK WASHINGTON PATERSON OREGON Approilmat* Seal* In Mil** B 10 19 20 McNARY DAM 4 23 2I 24^VuMATILLA 21 LEGEND » AL LA WALL* WASHINGTON OREGON • Bottom Sediment Samples — Water 8 Plankton Somples lig* 3. LOCATION OF SAMPLING POINTS 31 morning and early afternoon of August 14 and the second two during the same periods of August 15 , 1963 „ In order to reduce the volume and weight of the water samples so that they could be economically transferred to the laboratory, each was passed through a column of Dowex 50 cation exchange resin. The column , containing the zinc and cobalt, and other cations, was then shipped to the Sanitary Engineering Laboratory at the University of Illinois. The sampling apparatus which came into contact with the sample was made entirely of polyethylene with the exception of the ion exchange column and reducer which were glass. Each water sample was collected in midstream in polyethylene bottles and transferred to shore. Each was then filtered through a glass- wool wad in a funnel which drained into a 7170 ml polyethylene carboy. A 150 ml cylindrical glass separatory funnel containing 120 ml of Dowex 50 resin was attached and sealed, via a glass reducer, stopcock grease and rubber bands, to the outlet tap at the bottom of the carboy. The sample was passed through the resin at a maximum rate of approximately six ml/sq cm/min. A small sample of eluate was tested occasionally with total hardness indicator* to be certain that no leakage of cations from the resin had occurred. Laboratory tests had shown that the 120 ml of resin would completely remove the hardness from 74 liters of water contain- ing 100 ppm total hardness as CaC0 3 at the above flow rate. The hardness of the Columbia River was not measured, but was assumed, from published data (13), to be less than 100 ppm. No leakage of cations occurred when approximately 45 liter samples were passed through the cation resin columns. After each sample had been passed through the cation exchange column, the column was sealed and shipped to the laboratory. The fiberglass *Univer II, Hach Chemical Co., Ames, Iowa 32 filters used to strain each sample were placed in glass bottles, sealed and also shipped to the laboratory. PLANKTON SAMPLES Plankton samples were collected at the same location and time as the water samples. Each sample was collected in midstream with a #25 plankton net. The net was suspended in the flowing water for a period of from 15 to 30 minutes. The plankton caught in the net were then transferred to a glass jar 9 sealed, and shipped to the laboratory. Data resulting from the analyses of these plankton samples could only be recorded in terms of dry weight of plankton, as neither the numbers of plankton nor the volume of water from which the samples had been collected was known. BOTTOM SEDIMENT SAMPLES The Columbia River from the reactor area to Richland is a swift, « rocky-bottomed stream. Bottom sediments in this reach are nearly always limited to the near shore area and even there the sediments consist mainly of sand or gravel. Silt and mud could only be found in a few backwater areas. Samples of bottom sediments were taken along the shore-line of the river. Bottom sediment samples were collected by inserting an eight-inch inside diameter cylinder into the sediments, to a depth of three-quarters of an inch. The sediment within the cylinder was scooped into a plastic bag until a three-quarter- inch disc of sediment had been removed. Samples #1 and #H are exceptions. Sample #1 was composed of a layer one inch thick. Sample #*♦ was obtained by cutting a six- inch by four-inch rectangle, three- quarters of an inch thick, out of the sediment. Each sample was placed in 33 a plastic bag, sealed, placed in a cardboard container which was also sealed, and shipped to the laboratory. The samples were usually of clean, fine sand or silty 9and. A few samples contained some clay sized material. 34 4. RESULTS OF ANALYSES The results of the analyses of the four water, four plankton and twenty-four bottom sediment samples collected from the Columbia River on August 14 and 15, 1963, are presented in Tables 5 to 9. The results of the analyses for total gamma activity are presented in Table 5. The total gamma activity of plankton and bottom sediment samples and the activities of the residue and eluate from the acid washing of each of these samples is given. The total gamma activities of the water samples, as presented, are the activities of the cationic fractions of these samples, since they were collected on cation exchange resin at the site and eluted from the resin at the laboratory. The date of measurement of the gamma activities of each sample is given. Table 6 gives the results of the analyses for total zinc and total cobalt, both before and after separation. The values obtained before separation are approximate only. The results of the determinations of 65 60 radioactive zinc and radioactive cobalt, as Zinc ' and Cobalt , are pre- sented in Table 7. Activities of these two radionuclides are given as of the date of collection of the samples, August 15, 1963. The percentages of the total gamma activity due to Zinc ' and Cobalt in each sample and in the eluate from the acid washing of each sample, as of the date of measure- ment of the total gamma activities, are also presented in Table 7. Table 8 summarizes the bottom sediment data included in Tables 5 and 7, relating activities to the ground surface area of each sample. Table 9 is a summary of the results of analyses of the water, plankton and bottom sediment samples. TOTAL GAMMA ACTIVITY OF COLUMBIA RIVER SAMPLES 35 WATER 1 2 3 4 TEST DATE (*7 days) 10/10/63 10/17/63 12/9/63 12/9/63 Sample (cpm/g) 0690 0050 0072 0192 TOTAL GAMMA AcWlTY Residue Eluate (cpm/g) (cpm/g) Sample Adjusted* (cpm/g) PERCENT TOTAL GAMMA ACTIVITY ELUTED** LANKTON 1 2 3 4 2/17/64 2/17/64 2/17/64 2/17/64 667 372 542 193 2870 3240 2250 2790 2010 2200 87 89 81 91 BOTTOM IEDIMENTS 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 11/11/63 11/11/63 11/11/63 11/19/63 12/4/63 11/20/63 12/4/63 12/4/63 12/20/63 12/20/63 12/20/63 12/20/63 1/22/64 1/22/64 1/22/64 1/22/64 1/25/64 1/25/64 1/25/64 1/25/64 1/25/64 1/25/64 1/25/64 1/28/64 13.9 11.9 24 7 126 29 57 37 196 15.0 124 42.6 177 55.2 54.8 111 75.2 17.2 10.1 16.5 4.0 6.8 11.0 15.5 11.4 3.90 14,6 10,7 5.18 13.9 13,8 12.4 25.4 7,2 2.60 8,74 46.3 67.7 120 11,3 19.8 30.2 29.1 42.3 64.6 16,7 31.0 42.6 70,1 162 214 10.9 11.3 18.6 40.1 102 133 19,4 31.2 41.6 30.8 137 172 24,4 40.5 60.0 35.3 49.0 69,6 39,1 70,9 110 22,8 65.2 81.6 6.8 10.4 17.2 6.9 4.22 10.6 13.3 3.75 16.8 5.5 ,43 4.96 7.4 3.03 8.60 7.7 6.95 12.8 10.0 7.58 16.6 27 37 49 30 56 66 65 73 76 61 77 75 80 68 70 64 80 60 40 22 9 35 54 46 * Average of data for Initial Sample and k * Using Adjusted Sample and Eluate data. data for Residue plus Eluate, 36 Table 6. TOTAL ZINC AND TOTAL COBALT OF COLUMBIA RIVER SAMPLES SAMPLE TOTAL ZINC TOTAL COBALT DESCRIPTION Before After Before After Separation Separat ion Separation Separation (Approximate) (wg/g) (Approximate) (yg/g) (Hg/g> . — — ia ^ — WATER 1 » - - - 2 .00593 .120 - .00011 3 .00506 .056 - .00014 4 .00439 .048 - .00005 PLANKTON 1 1620 1960 45 3.5 2 1300 1750 27 3.4 3 1700 1060 31 1.2 4 1900 1870 160 1.9 BOTTOM SEDIMENTS 1 183 174 .31 .62 2 189 187 .24 .53 3 130 132 .06 .40 4 3.70 5.07 4.15 .87 5 166 177 .06 .09 6 154 110 .11 .12 7 44.5 35.6 ,03 .07 8 69.5 43.5 .02 .04 9 151 98.4 .13 .00 10 133 90.5 .03 .01 11 108 33.5 .04 .00 12 13.8 21.3 .00 .66 13 91.4 43.0 .06 .33 14 141 94.0 .14 .82 15 224 137 .10 .72 16 33.6 24.2 .02 .22 17 93.6 110 .20 .18 18 16.0 56,1 .15 .01 19 2.20 8.22 .34 .14 20 5.76 18.4 .04 .32 21 .51 7.93 .33 .18 22 3.85 9.77 .37 .18 23 7.48 5.26 .28 - 24 50.1 86.7 .20 .03 37 Table 7, RADIOACTIVE ZINC AND RADIOACTIVE COBALT OF COLUMBIA RIVER SAMPLES SAMPLE RADIOACTIVE ZINC AS ZINC 65 RADIOACTIVE COBALT AS 60 COBALT DESCRIPTION AUGUST 15, 1963 AUGUST 15. 1963 Activity Percen t*" of Total Activity Percent* of Total (pc/g) Gamma Activity of (pc/g) Gamma Activity of Sample Eluate — — Sample** Eluate WATER 1 2 .0199 160 _ .0011 16 _ 3 .0029 14 = .0000 .0 - 4 .0013 3 - .0014 5.8 - PLANKTON 1 8060 47 55 60 .9 1.0 2 5800 53 59 .0 .0 3 4830 50 63 63 1.7 2.1 4 5030 66 72 .0 .0 BOTTOM SEDIMENTS 1 .69 2 7 .34 1,8 6.8 2 5.13 14 38 .35 1.9 5.3 3 19.4 29 60 .55 1.7 3.4 4 3.07 12 40 .33 3.0 10 5 111 33 60 1.99 1.2 2.2 6 23.8 30 45 .94 2,3 3.5 7 62.0 35 54 1.00 1.2 1.8 8 30.9 27 36 1.10 2.0 2.7 9 201 32 42 9,50 3.3 4.4 10 13.0 25 40 .39 1.6 2.7 11 86.9 23 30 4.80 2.7 3.5 12 52.0 42 57 1.22 2.2 2.9 13 230 42 53 13.0 5.6 7.0 14 60.0 32 46 1.88 2.4 3.5 15 62.5 28 40 2.73 2.9 4.1 16 92.5 27 41 2.63 1,8 2.8 17 136 52 65 1.73 1.6 2.0 18 13.8 25 41 1.44 6.1 10 19 3.03 9 23 .64 4.4 11 20 3.34 6 28 1.28 .6 26 21 .00 .21 .3 37 22 4.67 16 48 .03 .2 .7 23 2.74 6 12 - - - 24 10.9 21 44 .00 .0 .0 * On date of measurement of total ** Using adjusted sample data. gamma activity. 38 O CT> * |UH « > m G H «H CO bO d g O C co 'H l£) NO) * 0) ^> > »CM ■h in c O "^ o u >H 3 X) bO (0 3 +JCM 'H C > -H O P. 3 ■P <-* o. c ID CM v a K ^ p e *3 H m mcn:*r^coo)cof» co CM co^-m^-co«o»nu)r^ ioioa>f-itocncnaoi-ir^oocoooioa)H HC0O(0OO- Oriowcim^tNoeoiflHwinuin CM iH d" CM IflHHrltN in f» 00 in c« cooor^ooocnOirooooooooooiDCMOOtoorH r^iocoocMco^-CMinc^iococoiDOicMcoind-ujcoor^r* CMCM^-COCMlDCMr»t»»COOtDiHiHJ-COind-CMCOinr^r-c^r*>r^r>*f*t^c-r«*r'«-r»f»r^r^r^r^r^r<-r^ COCOCOOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOCOOCOCOCO OOOd-00000000000000000000 minmcMmmmmminminmmmmmminmtnmmin ri(NMnH4-ooinio ^MO^nioiomH o>cncooocnocnoor-t OOOCMr^CMOOCMCMCMlOr-CM^-tDO oincoor>»t^cod-cod't^CMOincM OHCOCMCnOOOO>CO^HOCOCMOOO HH H H HHHHrHH H(N(i)*W(OM»0>OrltNn^ IftlON H H H iH iH CM CM CM CM CM m © b rt a» © p o 8 ip •H § 2 B O.CM • P rH o 03 O •H X) m mcn^-r>cocncoo o> cm ooo*«««« • « CDcOCnrHCOCncncOrHr>00 H 00 H H <-H H HCN CM H H O d" H O H O O O O O O d- in ifl n oi * oo co in co cn cn O O O CJ> O CM o h in co co cm CM o i i i o o CO I I CO o (O rH H CT> 3- H cn rH o o Notnmoj-oinootOri rHCncOOCOOOCMCOmOCO cor-HOincMin^-CMOco CM H 3" CM o 04 C71 C7> 00 OtNH rH O O o o o o o o o CO O CO CO ocouo oo in j- in cn oo r> (OH d- o in cn co H co o cn o cn o CO CM O rH 00 CO CM cm co co o i-h co m CM r-\ st & rH P '-N rH H O AH 60 o o o P rrj \ o o o o in CM CM O J3 M o o o in co CM C7» E- o a 1 • « • • • • • o w CO 00 H H CMooot«»cncMr>3-OrHOco comd-cooHoooooco •H m o co r> rH /—s cm m d- 10 o bO H o o P C \ | • © o O •H bO o o o o E- to a co m co r> >»• cn t^ o oo H H H H o co in ^- m cn co K P rH 43 (0 bO-^ P'H DO 0) >-^ it * o o o o d- t> cm in co oo o cn :* zt 3- co 3- * st * fa P rH CM 00 3" m cm cn o CM rH CM 00 CO CM rH Cn • • • • H CM CO .d-f>CMmr>omooooocorH t»» co co f>rHcod-o>cncocM rH rH H aocnorHCM 40 o> •H •H CO ifl ID ,Q a> O H c_> « 0) in > H •H 4-» +J O 0} o 3, •H 3 TJ < 2 o C co •H ID M 0> H 0) > - °H in o m +j w 3. Ml 3 < J.2 5 * p h x: /"» n> b0<^ "O P «H b0 01 o a> w 3 E- at a •H P a u UK o CM co^-md-covDioiot^- ooooo««oo cotDCDcocMa)d-r*m CO OOCOCOCOd-d-OOHCO o OCOf-tOC^.3-H in iH co in in co r» en m r» o in m 00 CO J" O CO OOCNOIlOCOCOCO CO ID ID CT> CO t-\ CN H O t>- J" o io r-^ J" CN O H f>^ niri bl P Hj \ O X> bO H o a. (ONMNOOHd-NCOO) COOOt^CNHOHCOrHH CO o «0 t) bO P C \ O •* bO H N a o o CN CN CN r^ - d- en co cm h in h oo r*»CN00CNCNCMlDC^CNd-«>O Or^r*co^-cod-c^cMOincN CNCnOCDCncOHOCOCNOCO H H H p id * «P O TJ P M-i 01 o a> p p A A bO bO •H «H 9 (0 II H 10 bOP O H P * * * * * * « * 5. DISCUSSION OF RESULTS TOTAL GAMMA ACTIVITY The total gamma activities of the samples were measured primarily to ascertain the proportion of the total activity of each sample caused by Zinc * and Cobalt . It was expected that samples having high total gamma activities would have correspondingly high Zinc ' and Cobalt activities. The results of these analyses have been presented in Table 5. Total gamma activities of the eluate plus the residue after acid washing of each bottom sediment sample should have been equal to the total gamma activity of each sample before acid washing. Due to the natural varia- tion in a heterogeneous material such as bottom sediment, it was difficult to obtain representative portions, and the results fluctuate considerably. The sample and the residue data are based on 10 to 15 g portions, whereas the eluate data is based on 250 to 350 g portions, both as dry weights. The eluate data is therefore much more precise than the sample and residue data. The percent elution of gamma activity by acid washing of plankton samples varied from 81 to 91 percent. The percent elution from bottom sediment samples by this treatment, varied from between 9 and 61 percent for samples having activities less than 30 cpm/g, to between 56 and 80 percent for samples having higher activities. There is an apparent increase in degree of desorption with increasing concentration of total gamma activity, indicat- ing that desorption in an acid medium is a function of the concentration of ions causing gamma activity associated with the sample. 42 It is assumed that assimilated ions producing gamma activity in plankton are not eluted by acid washing, and that these ions when adsorbed on the plankton surfaces are eluted by this treatment. The results indicate that adsorption of ions causing gamma activity is the major mechanism of uptake by plankton. However, these samples had been stored for several months in sealed glass containers, and the results might have been quite different if freshly collected samples had been analyzed. It is assumed that ions producing gamma activity occupying positions within the crystal lattice structures of clay particles in the bottom sediments, or incorporated into the sediments by other mechanisms, are not eluted by the acid wash treatment. It is also assumed that these ions when adsorbed on the surfaces of the sediments, or attached to charged sites on the surfaces of these particles, are eluted by acid washing of the sediment. The results indicate that adsorption and attachment to charged sites on the surfaces of the sediments, of ions causing gamma activity, are the major mechanisms of uptake by the bottom sediments if these samples contain high total gamma activities. COMPARISON OF TOTAL GAMMA ACTIVITY WITH ZINC* 5 AND COBALT 60 ACTIVITY Table 7 contains data concerning the percent of the total gamma activity of each sample and of the eluate from acid washing of each sample, on the date of measurement of the total gamma activity, caused by Zinc and by Cobalt . The total gamma activities of each sample and eluate have been converted from cpm to pc/g by assuming a counting efficiency factor of .230, based on that of the major radionuclide in these samples, Zinc , in 43 order to compute the percentages given in the table. 65 60 Three water samples were analyzed for Zinc ' and Cobalt . The activities of these samples were close to the detection limits of the 65 analytical equipment. Results, although doubtful, indicate that Zinc and Cobalt each comprised less than ten percent of the cationic activity of the water, several months after the samples were collected. The activity caused by each radionuclide appeared to decrease as the total cationic activity decreased. These results indicate that Zinc ' and Cobalt would not become major radionuclides in the water phase of the aquatic environment, even after a decay period of several months. 65 In the four plankton samples analyzed, the Zinc ' activities ranged from 47 to 66 percent of the total gamma activities of the samples, and from 55 to 72 percent of the total gamma activities eluted by the acid 65 wash treatment, at six months after sampling. The Zinc ' activity appeared to increase with decreasing total gamma activity. Cobalt activities were very low and accounted for less than two percent of the total gamma act i vi- ce ties at six months after sampling. The results indicate that Zinc ' is the major radionuclide associated with plankton at a period six months after samp I ing. 65 In the twenty-four bottom sediment samples analyzed, the Zinc activities ranged from to 52 percent of the total gamma activities of the samples, and from to 65 percent of the total gamma activities eluted by the acid wash treatment. For all samples having total gamma activities greater than 20 cpm/g, at least 23 percent of the activity of each sample, •nd at least 30 percent of the activity of each eluate, was caused by 44 65 Zinc . The total gamma activities of the bottom sediment samples were measured during a period of from three to five and a half months after sampling. The results indicate that for all sediments containing an appreciable total gamma activity, Zinc ' is a mojor radionuclide, during a period commencing several months after sampling. The Cobalt activities of the bottom sediment samples were low, but the determinations were reasonably precise. The percentage of the total activity caused by this radionuclide remained relatively constant, in a range of from 1.2 to 5.6 percent of the total gamma activity of each sample and from 1.8 to 10 percent of the total gamma activity of the eluate from acid washing of each sample, within the reach of the Columbia River upstream from McNary reservoir. Within the reservoir, the activity increased to 6.1 percent and then dropped off to almost 0.0 percent of the total gamma activity. In this reach, the activity increased to 37 percent and then dropped off to almost 0.0 percent of the total gamma activity of the eluate from acid washing. These data indicate that Cobalt is a minor radionuclide in the sediments, but that within McNary reservoir, it may be one of the major radionuclides that would be desorbed from the sediment under acid conditions. COMPARISON OF TOTAL ZINC AND TOTAL COBALT WITH ZINC 65 AND COBALT 60 Table 9 contains the results of analyses of the Columbia River samples for total zinc, total cobalt, Zinc ' and Cobalt 45 In the water and plankton samples, changes in total zinc concen- tration are accompanied by similar changes in Zinc ' activity. This trend is not followed by the bottom sediment samples. The Zinc ' activity of the sediments appears to be almost completely unrelated to the total zinc con- 60 centration of the sediments. The Cobalt activities of all samples appear to be unrelated to the total cobalt concentrations of the samples. 60 The Cobalt activities of water and plankton samples were close to the limit of detection and the results are doubtful. The Cobalt activity of the bottom sediments may be unrelated to the total cobalt concentration of the sediments, •6 Of the total zinc, less than 6x10 percent was radioactive. -4 Of the total cobalt, less than 5x10 percent was radioactive. Percent radioactivity did not appear to be related to sample type as it was similar in each of the water, plankton and bottom sediment types of samples. COMPARISON OF RESULTS WITH DATA OBTAINED BY OTHERS Water O'Connor et aj_. (1964) reported that of 34 samples of Columbia River water analyzed by the United States Public Health Service in 1952, 30 contained between 10 and 50 ppb of zinc, and the remaining four con- tained between 50 and 130 ppb of zinc. Silker (1964) stated that samples of water taken upstream of the Hanford reactors during the period from January 5 to August 17, 1962, ranged from 2.4 to 37.6 ppb of zinc and .001 to .087 ppb of cobalt. 46 The total zinc concentrations found in the three water samples analyzed in this study ranged from .048 to .120 u,g/g or from 48 to 120 ppb. The total cobalt concentrations of these samples ranged from .00005 to .00011 u-g/g or from .05 to . I I ppb. The data is consistent with the con- centrations reported by previous investigators. Fig. 1.3 depicts the results of monitoring the Zinc ' activity in Columbia River water at Pasco, from 1958 to 1963, by the Hanford staff, as reported by Foster e_t aj_. (1964) (36) -. 5 The Zinc activity at Pasco during August, 1963, ranged from .08 to 1.3 pc/g. Foster et al . also stated that the average activity during 1963 was .47 pc/g at Hanford, .38 pc/g at Richland and .22 pc/g at Pasco. Data on Cobalt activity in Columbia River water is not available. 65 The Zinc activity of Columbia River water found in this study varied from .0199 pc/g near Richland, to .0013 pc/g near McNary dam. The sample collected near Pasco contained .0029 pc of Zinc ' per gram of water. 65 Only three water samples were analyzed in this study, and the Zinc activities of the samples were close to the detection limit of the gamma scintillation counter. The results are considerably lower than data reported by Foster et aj_. The Cobalt activity of Columbia River water was also close to the detection limit of the gamma scintillation counter, but appeared to be about .001 pc/g of water. Plankton Davis (1963) (40) analyzed plankton samples collected from the Columbia River near Hanford in 1957, and found an average of 7300 pc of 47 Zinc * per gram wet weight of plankton. (Hanford, as shown on Fig. 6.1, is about ten miles downstream from the reactor area.) Assuming a dry to 65 wet weight ratio of .2, the concentration of Zinc ' reported by Davis is equivalent to 1460 pc/g dry weight of plankton. Green algae samples at this location contained approximately 2,500 pc of Zinc ' and 30 pc of 60 Cobalt per gram dry weight of plankton. The green algae contained less than 50 |jig of zinc and less than 5 |xg of cobalt per gram ashed weight, as reported by Davis. The reported concentrations of zinc and cobalt would have been considerably less, if reported on a dry weight basis instead of an ashed weight basis. In the present study, plankton samples contained from 1060 to 65 1960 pig of zinc, 1.2 to 3.5 p,g of cobalt, 4830 to 8060 pc of Zinc and to 63 pc of Cobalt data, the concentrations and activities of the plankton samples were high enough to assure good analytical precision and accuracy. 65 The data are consistent with that reported by Davis for Zinc ' activity and Cobalt activity. The data reported by Davis for Zinc and cobalt are not very consistent with the concentrations of zinc and cobalt found in this study. Bottom Sediments Samples of bottom sediments were analyzed in March, 1962, by the Hanford staff. These samples were collected from the shorelines of the Columbia River between Hanford and Richland. They were taken primarily from the shorelines of islands within this reach of the Columbia River. Zinc ' activities ranged from 170 to 880 pc/g and Cobalt activities 65 ranged from 5.6 to 69 pc/g dry weight of sediment. Zinc caused one- third of the total radioactivity of these samples. The Hanford staff also 48 took core samples from the bottom of McNary reservoir in 1962. These samples averaged 1350 pc of Zinc ' and 47 pc of Cobalt per gram dry weight of sediment, at the sediment-water interface. Data on concentrations of zinc and cobalt in Columbia River sediments are not available. The results of this study indicate a range of from 5 to 187 ng of zinc and from .00 to .87 u,g of cobalt per gram dry weight of sediment, in the study reach of the Columbia River. There appears to be an average concentration of 71 u.g of zinc and .28 u.g of cobalt per gram dry weight of sediment, adsorbed or exchangeable on the sediments of the study reach. 65 Zinc ' activities increased from .69 pc/g upstream of the reactor area to 230 pc/g between Hanford and Richland, and then decreased to less than 5 pc/g within McNary reservoir. A sample taken below McNary dam contained 65 10.9 pc of Zinc ' per gram dry weight of sediment. The highest value obtained in McNary reservoir was 13.8 pc/g, and the sediments averaged about 4 pc/g in the reservoir. In the reach between the reactor area and Richland, Zinc * averaged approximately 90 pc/g. Cobalt activities varied from .34 pc/g upstream of the reactor area to 13.0 pc/g between Hanford and I Richland and then decreased to less than .2 pc/g near McNary dam. The 60 highest value for Cobalt obtained in McNary reservoir was 1.44 pc/g, and ! the sediments taken from the reservoir averaged less than 1.0 pc/g. Cobalt averaged approximately 3 pc/g in the reach between the reactor area and | Richland. 65 The Zinc ' activities obtained in this study for sediments in the reach between Hanford and Richalnd average 24 percent of the activities 49 found by the Hanford staff in 1962. The concentrations of Zinc ' found in McNary reservoir average .3 percent of the concentrations found in the 1962 study of the reservoir sediments. The results indicate that sediments along the shoreline of the reservoir contain much smaller concentrations of Zinc than do the sediments in the bottom of the reservoir. The Cobalt activities of sediments obtained in this study in the reach between Hanford and Richland average 16 percent of the activities found by the Hanford staff in 1962. The Cobalt activities obtained in this study in McNary reservoir average approximately two percent of the activities found in the 1962 study. Both of these percentages are in the same ranges as the percentages found for Zinc CONCENTRATION RATIOS The Columbia River water contained an average of .072 u.g of zinc and .00010 u>g of cobalt per gram of water. The Zinc ' activity, as measured by the Hanford staff on the date of sampling, was .11 pc/g at Pasco. The Cobalt activity, as found in this study, averaged .0008 pc/g of water. Plankton samples collected from the study reach contained an 65 average of 1660 p,g of zinc, 2.50 u,g of cobalt, 5940 pc of Zinc ' and 30 pc of Cobalt per gram dry weight of plankton. Bottom sediment samples collected from the study reach contained an average of 71 pg of ztnc, .28 |xg of cobalt, 52 pc of Zinc ' and 2.1 pc of Cobalt per gram dry weight of sediment. The ratios of the concentrations found in plankton and bottom sediments of zinc, cobalt, Zinc * and Cobalt , to the concen- trations of these elements and radionuclides in the surrounding water, 50 based on average values within the study reach of the Columbia River, are presented in Table 10. Table 10 CONCENTRATION RATIOS OF COLUMBIA RIVER PLANKTON AND BOTTOM SEDIMENT SAMPLES TO COLUMBIA RIVER WATER Analysis Sample Type Plankton Concentration Ratio Total Zinc 20,000 Bottom Sediments 1,000 Total Cobalt Plankton 20,000 Bottom Sediments 3,000 7 . 65 * Zinc Plankton 50,000 Bottom Sediments 400 Cobalt 60 Plankton 4,000 Bottom Sediments 300 65 * based on Hanford staff evaluation of Zinc ' activity in water SIGNIFICANCE OF ZINC 65 AND COBALT 60 CONCENTRATIONS Eisenbud (1963) (41) has stated that the United States Atomic Energy Commission's recommended maximum permissible concentrations in water for non-occupational exposure are 100 pc of Zinc ' and 50 pc of Cobalt per gram of water. If all of the Zinc '* and Cobalt activity contained in the plankton and bottom sediments of the Columbia ,Rlver were somehow suddenly released back into solution, the resulting concentration of these radio- nuclides in the water would remain below these limits, because of dilution by the large volume of water. However, an industrial effluent containing • high acidity and a greater density than the receiving water, discharged 51 into the Columbia River a few miles upstream from Richland or Pasco, could accumulate high concentrations of Zinc ' and Cobalt , by desorption of these radionuclides from bottom sediments. It would be possible for this density current to enter Richland or Pasco's municipal water supply intake. It is therefore necessary for both of these cities to maintain continuous monitoring of the radioactivity in the water at their water treatment plants. An automatic alarm and by-pass system for water containing exces- sive radioactivity is also necessary. If continuous water monitoring and automatic by-pass systems are maintained, the occurrence of Zinc ' and Cobalt in their present concentrations in the Columbia River water, plankton and bottom sediments is very unlikely to produce a significant radiation exposure hazard to the people using the Columbia River as a source of drinking water. 52 REFERENCES 1. Conard, R. A., et al . Medical Survey of Kongelap people five and six years after exposure to fallout, Brookhaven National Laboratory, U.S.AEC BNL-609 (T-I79) ( I 960) . 2. Cohn, S. H., Love, R. A., and Gusmano, E. A., Zinc-65 in Reactor Workers, Science . 133 . 1362 (1961). 3. Van Dilla, M. A. and Engelke, M. J., Zinc-65 in Cyclotron Workers, Science . 131 , 830 (I960). 4. Watson, D. G., Davis, J. J. and Hanson, W. C, Zinc-65 in Marine Organisms Along the Oregon and Washington Coasts. Science , 1 33, 3467 (1961). 5. Perkins, R. W. , ana Neilsen, J. M., Zinc-65 in Foods and People, Science , 129, 94 (1959). 6. Fitzgerald, B. W., Rankin, J. S., and Skanen, D. M. Zinc-65 Levels in Oysters in the Thames River (Connecticut), Science , 1 35 , 926 (1962). 7. Perkins, R. W., and Nelson, J. L., Behavior and Transport of Radionuclides in the Columbia River between Hanford and Vancouver, Washington, Limnology and Oceanography , II, 2, (1966). 8. a. O'Connor, J. T. , and Renn, C. E. , Soluble-Adsorbed Zinc Equilibrium in Natural Waters, Jour. AWWA . 56 ; 1005 (August 1964). 8.b. Zinc Concentrations in Rivers of the Chesapeake Bay, Jou r . AWWA , 56 , 280 (1964). 9. Heide, F. and Singer, E., The Copper and Zinc Content of the River Saale, Naturwissenschaften. 41; 498 ( 1 954) . 10. U.S.P.H.S. (1946) Drinking Water Standards . U.S. Govt. Printing Office, Washington, D.C. 11. Braidech, M. M. , and Emery, F. H. , The Spectrographic Determination of Minor Chemical Constituents in Various Wpter Supplies in the United States, Jour. AWWA . 27, 557 (1935). 12. Kehoe, R. A., and Cholak, J., and Largent, E. J., The Concentrations of Certain Trace Metals in Drinking Water, Jour. AWWA . 36, 637 (1944). 13. Robeck, G. C, Water Quality Studies on the Columbia River , USPHS, Taft Sanitary Eng. Center (1954). 14. Kleinkoff, M. D. , Spectrophotometry Determination of Trace Elements in Lake Waters of Northern Maine, Geo!. Soc. America Bui I ,.71 , 1232 ( ' 960) . 53 15. Morita, Y. , Copper and Zinc Content of Seawater, J. Chem. Soc. Japan, 71 . 246 (1950). 16. Hutchinson, G. E., A Treatise on Limnology , John Wiley, New York (1957). 17. McConnel I , Bear Lake, Bulletin, State of Utah, Division of Fisheries and Wildl ife, (1957). 18. Boyle, R. W., et al . , Heavy Metal Content of Water and Sediments in the Streams, Rivers, and Lakes of Southeastern Nova Scotia, Geol . Soc . Canada, paper 58-1, (1958). 19. Sprague, J. B., and Carson, W. V., Chemical Conditions in the Northwest Hiramichi River during 1964, Fisheries Research Board of Canada , (1965). 20. Sprague, J. B., and Carson, W. V., Chemical Conditions in the Northwest Miramichi River during 1963, Fisheries Research Board of Canada , (1964). 21. Durum, W. H. , and Haffty, J., Implications of the minor Element Content of some Major Streams of the World, Geochim et cosmoch. Acta, 27 , I, (1963) 22. Livingstone, D. A., Data of Geochemistry. Sixth Edition, Chapter G, Chemical Composition of Rivers and Lakes. U. S. Geol, Survey, paper 440-G , (1963). 23. Sverdrup, Fleming, Johnson, The Oceans , Prentice-Hall (!942). 24. Krumholz, L. A., and Foster, R. F., Accumulation and Retention of Radioactivity from Fission Products and other Radiomaterial s by Fresh- Water Organisms, The Effects of Atomic Radiation on Oceanography and Fisheries . 26. Bongis, P., Sur I 'effet biologique du zinc en eau de mer, Comptes rend us des seances de I 'Academic des Sciences, 253 , 740, (1961). 28. Jenne, E. A., Controls on Mn, Fe, Ni, Cu, and Zn Concentrations in Soils and Waters: The Dominant Role of Hydrous Mn and Fe Oxides, U.S. Geol. Survey , Denver. 29. Boroughs, H., Chipman, W. A., and Rice, T. R. , Laboratory Experiments on the Uptake, Accumulation and Loss of Radionuclides by Marine Organisms, NAS Pub I . 551 . Wash., D. C. 30. Chipman, W. A.,^Rice, T. R. , and Price, T. J., Uptake and Accumulation of Radioactive inc by Marine Plankton, Fish, and Shellfish, U. S. Fish and Wildlife Service, Fisheries Bui letln 135 . (1958). 31. Mori, T. , and Saiki, M. , Studies on the Distribution of Administered Radioactive Zinc in the Tissues of Fish, Vol. II, Japan Society for the Promotion of Science . Veno, Tokyo. 54 33. Polikarpor, G. G., Radioecoloqy of Aquatic Organisms , Reinhold Book Division, 1966. 34. Vinogrador, A. P., The Elementary Chemical Composition of Marine Organisms, Mem. Sears Found. Mar. Res ., 2, (1953). 36. Foster, R. F., et al . , Evaluation of Radiological Conditions in the Vicinity of Hanford for 1963, HW-80991 (1964). 37. Evaluation of Radiological Conditions in the Vicinity of Hanford for 962, HW-76526 (1963). 38. McConnon, D. , Dose Rate Measurements of Beaches and Islands on the Columbia River between Ringold and Richland, HW-72229 (1962). 39. Nielsen, J. M., Behavior of Radionuclides in the Columbia River, TIP - 7664 (1963). 40. Davis, J. J., Accumulation of Radionuclides by Aquatic Insects, HW-SA-3050 (1963). 41. Eisenbud, M., Environmental Radioactivity , McGraw-Hill (1963). 55 II. ZINC ADSORPTION BY SEDIMENTS IN A SALINE ENVIRONMENT I. INTRODUCTION ZINC IN SALT WATERS Within the range of pH encountered in natural waters, zinc is accumulated on river and estuarine sediments; by algae and plankton; and by crustaceans, fish, and other marine organisms. Zinc has been found to be concentrated hundreds, or even thousands, of times by marine organisms such as oysters, clams, and fish. These findings have spurred interest in the zinc equilibria that exist in a saline environment. It is of interest to know whether the zinc that is accumulating in these organisms is received by them from the water or is removed from a sorbed state on sediments, algae, plankton, or other suspended materials, which feed into estuaries or the oceans from fresh-water rivers or lakes. The answer most probably is con- tained in a complex system of physical adsorption, cation exchange, isotopic dilution, chemican precipitation, and shifts in zinc solubility caused by progressive changes in alkalinity, and, ultimately, pH. This study includes a review of some of the available literature dealing with laboratory studies of the uptake of zinc by sediments and marine biota, as well as a general review of some of the chemical and physical processes that influence zinc distribution, such as cation exchange and estuarine mixing. There are also reported several laboratory experiments conducted by the author and designed to study zinc uptake by river sediments in an increasingly more saline (estuarine) environment. 56 SURVEY OF THE LITERATURE UPTAKE OF ZINC BY MARINE BIOTA Algae and Plankton Many species of algae and plankton have been found to concentrate zinc from thousands to tens of thousands of times over the concentration in the surrounding sea water (25) (15), Watson, Davis, and Hanson (31) found zinc-65 to be the most abundant gamma emitter in plankton and sessile algae near the mouth of the Columbia River, Gutknecht (11) (12) has found zinc uptake by several species of marine algae to be increased by the presence of light, indicating that some uptake may be attributed to metabolic activity, Rona (27) has re- ported that the best known biological function of zinc is its acting as a co- factor in the enzyme, carbonic anhydrase. Nonetheless, it is Gutknecht* s opinion (11) (12) that the primary mechanism of zinc removal from solution by algae is not metabolic activity, but rather adsorption involving cation exchange, Gutknecht (12) has found further that dead algal cells accumulate zinc to a greater degree than do live cells and that uptake is promoted by increased pH, Both factors tend to substan- tiate the conclusion that algal uptake of zinc is primarily adsorptive. Rice has concluded (25) that planktonic uptake of zinc in a specific experiment he has reviewed was much greater than metabolic requirements would dictate, Watson, Davis, and Hanson (31), in their study near the mouth of the Columbia River of planktonic uptake of gamma emitters, including zinc-6'5, found that maximum accumulation occurred at periods of lowest tides and, furthermore, when the tide was flowing seaward. This indicates 57 not only that the zinc was least diluted at this time and hence that the concentration gradient was greatest between the zinc in the water and on the algae; but also suggests that the concentration of competing ions (salinity) was lowest, and that, therefore, zinc exchange onto algae might be greater in fresher water „ Generally it has been found that uptake of zinc by algae and plankton is very rapid, and that both the rate of uptake and the equilib- rium concentration in a given organism are functions of pH, original zinc concentration in and on the algae, and the chemical composition of the water. There is reason to believe that other factors such as surface area/volume ratio, chemical composition of the cell and cell wall, and the rate of agitation of the surrounding media all play a contributing role (15)o Shellfish A review of the use of zinc in ecological studies by Rice (25) indicates that organisms of the higher trophic levels accumulate zinc at rates more dependent on their metabolic functions than do the algae and plankton o For example, Rice found that accumulation of zinc-65 by the brine shrimp, Artemia salina , was 2„6 times as great when the zinc was taken from algae on which the shrimp had fed than when the zinc was taken from the surrounding water (25) Furthermore, the male Artemia were able to concentrate the zinc-65 by a factor of 76 times over that in the water, whereas the females attained a concentration factor of 125 (25)j the inference from Rice v s report is that the differences in concentration factors between the two sexes of this species resulted from differences in their metabolic activity „ the blue crab , Callinectis sapidus, in which the initial uptake rate was very rapid „ During the molt of the crab, however, the zinc content was lower; but uptake began anew following the molt, though at a much reduced rate. The change in rate was attributed to the physical and physiological differences in the organism after the molt as compared to before the molt. In the same study, the same organism was also found to release accumu- lated zinc to the environment at a much slower rate at 4.5° to 14° centi- grade than in water at 25° centrigrade (25). Still another zinc-retention study reviewed by Rice (25), this with the hard shell clam, Mercenaria mercenaria , indicated that zinc-65 loss from the organism was improved by transferring the clam from a laboratory container of sea water into naturally occurring sea water. Rice (25) surmised that the increased loss of zinc in natural sea water was the result of an improved physiological environment. O'Connor (18) has found that the largest percentage of zinc-65 I uptake by clams is centered in the siphon. He found that 30.1 percent of the total activity was in the siphon, and the next largest accumula- tion, 18,1 percent, was in the shell (18). 58 Chipman, et^ a^. (4) reported concentration factors of zinc by 5 »s of oysters to be higher than 10 , though the c< zinc in the sea water was only about 10 parts per billion. 5 two species of oysters to be higher than 10 , though the concentration of Fish Rice (25) reports that some tuna have been found to contain sufficient zinc-65 to render them unsafe for human consumption. Several investigators (13) (15) (25) have reported zinc-65 to be one of the more 59 predominant, if not the most predominant, radionuclides found in fish. Lowman (15) found zinc-65 to contribute as much as 90 percent of the total radioactivity in several tunas six weeks after a nuclear weapon's test at Eniwetok Proving Ground in 1958; even though zinc-65 comprised only 6 84 percent of the total radioactivity in the sea water. The increasing predominance of zinc-65 with time in marine organisms has been attributed by several reporters (13) (15) (25) to the relatively long half-life of zinc-65 (245 days) and to some degree to isotopic dilution by a reservoir of stable zinc within the organism (15), There is some doubt as to the exact source of zinc-65 accumu- lated by fish (13), but generally it is felt to be contributed by the food of the fish much more than from the water (15) (25). UPTAKE OF ZINC BY SEDIMENTS Distribution of Zinc by Sedimentation Several investigators (8)(20)(28) have found that zinc is removed rapidly from the liquid phase of a stream containing suspended sediment. It also is recognized generally that the settling of these sediments in more quiescent bodies of water effects a large percentage removal of radionuclides from the water (6)(22). The mechanism of zinc sorption is primarily dependent on the size of suspended particles involved. It is felt that sand and silt particles, for the most part, physically adsorb zinc; whereas clay particles have been found to have a marked capacity for cation exchange, though some secondary adsorption occurs on clay surfaces also (26), There are , nonetheless , both advantages and disadvantages involved with sedimentation of sorbed radionuclides. An advantage is that, where sedimentation occurs, a large portion of the zinc is removed 60 from the liquid phase from which the lower trophic level organisms adsorb zinc directly. Thus zinc-65 may be precluded from entering the food chain to man. However, sedimentation may result in a large concentration of zinc-65 in the stream or estuarine beds, and subsequent reducing con- ditions in the top layers of sediment may redissolve the zinc in harmful concentrations , Factors Influencing Cation Exchange The composition of the adsorbent material, the primary reference here being to clay particles, is one of the major factors influencing a cation exchange equilibrium. The force of attraction for a cation in solution exhibited by the ionic constituents of a clay apparently is weakest in those ions located on plane surfaces of the lattice structure. Ions of the clay structure located on edges exert a stronger adhesive force, and those in corner positions exert the strongest force of the three (26), Furthermore, the accessibility of the three types of sites -- basal surfaces, edges, or corners — can affect the exchange capacity of a single clay or can be an important factor in accounting for the dif- ferences among the exchange capacities of the several clays. Certain substances may obstruct or clog the exchange sites, Dion (5) found that ferric oxide in both hydrated and nonhydrated form exhibits a clogging effect on clay minerals, Hendricks (14) suggested that some organic ions adsorbed on the basal surfaces of montmorillonite may obstruct the exchange positions. The composition of the surrounding solution is also an extremely important factor in cation exchange. Temperature, however, at least in the range found in most surface waters , has been reported to have very little, if any, effect on the exchange equilibria involving clays (26), The pH of the watercourse, on the other hand, has a marked effect on exchange equilibria „ Several investigations have been reported (26) in which linearity of the relationship between pH and exchange capacity has been found „ In all cases reported by Robinson (26) in which pH values were between 5 o and 8 o 0, increased acidity led to a corresponding decrease in exchange capacity „ Most investigators have found that increasing the concentration of a particular cation in the solution increases its replacing power in relation to the exchange equilibrium Some investigations have been reported (26) that show that exchange capacity of a clay for a particular cation is increased with increased concentration of that cation, but that the increase in exchange capacity is not a direct function of the con- centration . Some equations have been reviewed by Robinson (26) that show exchange capacity to be a logarithmic function of hydrogen ion concentra- tion, the concentration of the cation to be exchanged, and the valence of the cation* McHenry (16) (17) found uptake of strontium and cesium by a composite soil near the Hanford works to be a function of the concentra- tion of these cations Uptake of a specific radionuclide has been found to be decreased, however, by increasing concentrations of other, competing cations (16) (17), There is some disagreement about the effects of different anions on cation exchange capacity, Nezyaka reported in a personal communication to Grim (10) that he found a difference in the replaceability of Na and +2 Ca in montmorillonite depending on whether calcium hydroxide or sulfate was used. Jenny and Engabaly and Marshall have suggested, however, that the formation of basic salts with the clay and a soluble anion, such as 62 clay-Zn(OH) for example, complicates the question of whether a portion of the effect is the result of a pH shift (26) Other writers have found anions to have little, if any, influence on cation exchange (26)„ DISTRIBUTION OF POLLUTION BY ESTUARINE MIXING Turbulent dispersion of any pollutant must occur prior to either the sorption of cations by sediments or the biosorption or meta- bolic uptake of cations by marine organisms „ Dilution by dispersion also affects the degree of uptake, since sorption is concentration dependent (3) A major portion of the turbulent energy necessary for mixing is supplied to an estuary as a result of tidal oscillations For complete mixing to occur, however, the combined energies of the tidal oscillations and the flow of the inland stream emptying into an estuary must be great enough to overcome the density gradient that may form between the more dense salt water and the less dense fresh water Such density gradients are capable of maintaining a pollutant in the less dense surface layer that is formed and of precluding a soluble cation from reaching the bottom sediments for subsequent adsorption or exchange -- except by the slower diffusion process (23)(3) If pollutants are maintained in the surface layers, they are generally within the euphotic zone and remain available for uptake by the marine biota that are in the food chain to man (21), With regard to sedimentation in estuaries, Einstein and Krone (7) have reported that as little as 1 gram per liter of salinity (2.9 per- cent of the salinity existing in sea water), in addition to wave action and oscillatory tidal movements, effects significant flocculation of sus- pended sediments o The cations present in the sea water cause a reduction in the stability of dispersed, negatively-charged, colloidal particles s 63 3 . LABORATORY EXPERIMENTS PURPOSE AND OBJECTIVES The literature herein reviewed indicates that a primary mechanism of radionuclide removal from the soluble state in natural watercourses is adsorption-exchange onto suspended silts and clays. It appeared to be appropriate, therefore, to study the effects on zinc- sediment adsorption equilibria resulting from changes in the chemical composition of the environment. A more specific objective was to study the changes in zinc sorption on sediment as the salinity of the environ- ment was increased, analogous to the travelling of zinc-bearing fresh water and sediment into an increasingly saline estuary. It was also an objective of these experiments to determine whether disruption of a fresh-water, zinc-sediment equilibrium by in- creasing salinity might be predicted according to classical adsorption theory . MATERIALS AND METHODS Reagent solutions used throughout the experiments herein reported were prepared with demineralized water. Such zinc- free water was prepared by passing distilled water through a mixed-bed ion exchange column*. This water was employed for preparing HC1 and Na^COi solutions used for pH control, in diluting distilled HC1 stock solutions for use in washing glassware (to render it zinc-free), and for preparing arti- ficial sea water. Ml *ion-X-changer, Illco-way Research Model De-ionizer, Illinois Water Treatment Co., Rockford, Illinois 64 Artificial sea water was prepared according to the recipe of Lyman and Fleming (29), which appears as Table 1. All the constituents were weighed carefully; and, as the crystals, were made up to five liters with demineralized, zinc-free water. This is to say that stock solutions of the hydroscopic materials such as calcium and magnesium chloride were not prepared and checked by titration as an extra precaution to eliminate the error of weighing adsorbed water „ The accuracy of the weight deter- minations as made, however, was felt to be adequate. (A stock solution TABLE 1 COMPOSITION OF ARTIFICIAL SEA WATER - LYMAN AND FLEMING (29) Salt Concentration, gm/kg NaCl 23.476 MgCl 2 4.981 Na 2 S0 4 3.917 CaCl 2 1.102 KC1 0.664 NaHCO 0.192 KBr 0.096 H 3 B0 3 0.026 SrCl 0.024 NaF 0.003 of NaF was prepared by weighing ten times the prescribed amount and adding the appropriate volume of solution to the sea water. This was done to avoid weighing an extremely small quantity.) Since these experiments were designed to monitor zinc uptake by river sediment at a constant pH, but in an environment of increasing salinity, the experimental system included a soil-water slurry and various 65 concentrations of stable zinc tagged with zinc-65 tracers The soil used in all the experiments was a sample of river sediment taken in August 1963, from the Columbia River downstream of the Hanford reactors, A grain-size analysis of this material is reported in Table 2, This soil had been kept moist since its collection, and dry weight determinations were made according to the moisture content of the soil as determined on the day of the experiment. The pH of the experimental system was monitored continually with a glass and calomel electrode pair mounted within the four-liter reaction vessel. These electrodes were connected to a battery-operated pH meter*. It was possible to read and maintain the pH of the system within 0,05 pH unit with this equipment. The pH was adjusted to 8.00 with HC1 or Na_C0- as required. The value of 8.00 was chosen merely because the pH of the Columbia River, from whence the sediment had come, is normally near 8,0 (30), and because the pH of sea water is normally between 7,5 and 8,4 (29). The main concern was that the pH be constant* A stable zinc solution was prepared by dissolving reagent grade, 20 mesh zinc metal in several milliliters of concentrated HC1 and diluting with zinc- free water, such that 1 ml of solution contained 1.20 mg of zinc. The zinc-65 tracer used throughout the study was added from a stock solution so prepared that a 10 ml sample would count approximately 2000 counts per minute above background. The amount of zinc in the tracer was computed as follows s "Beckman pH Meter, Model G, Beckman Instruments, Inc., Fullerton, California, 66 TABLE 2 GRAIN-SIZE ANALYSIS OF COLUMBIA RIVER SEDIMENT - ASTM (2) Percent Remaining Particle Diameter, mm Sieve Analysis Hydrometer Analysis 99 ,75 99 ,60 97 ,30 86 ,6 77 ,5 65 ,9 42, ,2 40 ,1 35 ,6 33 .2 30 ,85 25 ,73 23 ,15 20 ,38 15 ,00 7 .29 5 ,36 2.00 1.19 0.420 0.210 0.149 0.074 3.24 x 10 2.30 1.66 1.22 8.46 x 10 6.20 4.30 3.15 2.26 4.20 x 10 9.75 x 10 -2 -3 -4 -5 67 Stock Tracer Solution = 0,08 mc zinc-65 in 100 ml = 0.08 x m> s 0.0008 mc/ml = 0,8 uc/ml Specific Activity of Tracer* = 476 mc/gm = 0.476 uc/ug Tracer Solution Concentration = - ,* < ; = 1.68 yg/ml 0,476 uc/ug • The addition of 8 milliliters of zinc-65 tracer solution to 500 milliliters of water yielded a desirable counting level in subsequent 10 ml samples, but it also resulted in an increase of zinc concentration of 26.88 ug/1. This amounted to an increase of only 0,02688 mg/1. Hence this addition of zinc was small as compared to the total zinc concentration and was disre- garded, except when the total zinc content used in an experiment was equal to or less than 0,25 mg/1. The original zinc content of the Columbia River sediment was determined prior to this series of experiments (33). Owing to the com- plexity of the extraction procedure used, however, the results are believed to be somewhat inaccurate, though they indicate the zinc content of this sediment to have been approximately 40 ug/gm (dry weight basis). Only -8 2 x 10 percent of this zinc was found to be radioactive (33). Because these numbers were possibly inaccurate and because the zinc content per liter added to the system from the soil was relatively small, the amount of zinc already absorbed by the soil was disregarded. Normal experimental procedure consisted of the following steps: 1. A predetermined amount of Columbia River sediment was added to a four-liter Pyrex beaker containing 500 milliliters of zinc-free demineralized water. 2. This mixture was stirred to a homogeneous slurry with "Computed by Oak Ridge National Laboratory prior to shipment. Daily corrections in specific activity to account for decay would have been inconsequential, and, therefore were not made. 68 a magnetic stirring apparatus, and stirring was continued throughout the experiment. 3, Stable zinc and zinc-65 tracer were added from their respective stock solutions. 4, The pH of the mixture was adjusted to 8.00 with several drops (as needed) of 2N Na.CO.. 5 , Two 10-ml samples for zinc-65 counting were pipetted from the reaction vessel and filtered through a 0,45 y membrane filter*. 6, Stepwise additions of artificial sea water were made to the mixture. At each level of salinity the pH was readjusted as necessary to 8,00, and more duplicate samples were taken for counting. 7, The liquid samples were counted in a well-type scin- tillation counter containing a thallium-activated, sodium iodide crystal and having a counting efficiency for zinc-65 of about 23 percent. The total time required for an entire experiment including sampling at seven levels of salinity was approximately two hours. The most time-consuming facet of the operation was the establishment of pH equilibrium at 8.00, This became increasingly easier and faster with each successive addition of artificial sea water, since this water was apparently highly buffered to a pH between 7.9 and 8,0, *Millipore Filter Paper, Type HA, Millipore Filter Corporation, Bedford, Massachusetts , 69 Possible additions to the total zinc content occasioned by leaching from the sides of the Pyrex beaker were neglected. Possible losses of zinc during sample filtration by sorption on the filter mem- brane also were disregarded , O'Connor has concluded previously (18) that such losses are small, though there may be some loss on the fritted glass filter septum , The filter septum used here was washed with HC1 between experiments to reduce such error to a minimum,, EXPERIMENTAL RESULTS Zinc Adsorption in Saline Water by Different Concentrations of Sediment A series of four experiments was conducted to determine the effect of suspended solids concentration on zinc adsorption under estuarine conditions, i,e,, under varying conditions of salinity,, To slurries of different concentrations of Columbia River sediment in demineralized water were added 2 mg/1 of stable zinc and 6,4 yc/1 (26 88 yg/1) of zinc-65 The pH of the mixture was adjusted to 8,00, and samples were taken for zinc-65 counting. Then stepwise addi- tions of artificial sea water were made, and two more samples were taken at each level of salinity. During the course of an experiment the volume of liquid in the reaction vessel was increased from 500 ml to approximately 2000 ml resulting from additions of sea water and in spite of depletions for sampling. The results of these experiments, shown in Figure 1, include the combined effects of both additional salinity and dilution on the zinc concentration in solution. These results are tabulated in Appendix A, Prior to the addition of any sea water, zinc was absorbed appre- ciably by the sediment, the greatest uptake occurring where the sediment concentration was greatest. The first addition of sea water, bringing 70 2.0 1.6 E z o o to I- < t- z LU o z o o u z 1.2 0.8 0.4 ORIGINAL STABLE Z IN f CONCENTRATION =2.0 mg/ 1 pH = 8.00 40 60 PERCENT SEA WATER 100 FIGURE 1. EFFECT OF SOLIDS CONCENTRATION ON ZINC UPTAKE BY SEDIMENT WITH VARYING PERCENT SEA WATER. 71 the sea water content to five percent , caused a marked release of the adsorbed zinc to solution Further additions of sea water were followed by further release of zinc from the soil, but these further releases were masked by the increased dilution . Such dilution caused the zinc concen- tration in solution to decrease, in most cases to levels below those caused by the initial adsorption in the "fresh" water. To isolate the effects on zinc uptake caused only by the salinity increases , it was necessary to correct the concentrations of zinc remaining in solution shown in Figure 1 by a dilution factor, which, of course, increased from one level of salinity to the next. The results from the same four experiments, corrected for dilution, are shown in Figure 2. It may be seen from Figure 2 that the first addition of sea water resulted in the greatest release of zinc, but that subsequent addi- tions of salinity promoted further desorption. Zinc Adsorption in Saline Water at Different Original Zinc Concentrations A series of experiments was conducted to determine the effects of salinity on zinc uptake when there were different original concentrations of zinc in the system. In the four experiments performed, the original zinc concentrations were 0.100, 0.277 (both including the zinc contributed by the added zinc-65 tracer), 0,500, and 1.00 mg/1. An original sediment concentration of 500 mg/1 was employed throughout the series, and the same quantity, 6.4 yc/1 (26.88 yg/1), of zinc-65 tracer was used in each of the four experiments. The results of these experiments are shown in Figure 3. As in the previous experiments the zinc was adsorbed appreciably by the sediment when added to the systems containing only demineralized 72 E Z o \- Z> _J o CO z o I- < h- z LU u z o u o z ►H M 2.0 1.6 ORIGINAL SOLIDS CONCENTRATION = 0.100 g/1 1.2 0.8 O.k ORIGINAL STABLE ZINC CONCENTRATION = 2.0 mg/1 pH =8.00 20 kO 60 PERCENT SEA WATER 80 00 jFIGURE 2. SALINITY EFFECT: EFFECT OF SOLIDS CONCENTRATION ON ZINC UPTAKE BY SEDIMENT (CORRECTED FOR DILUTION). 73 1 .0 C7> e z o O z o l-H I- < I- z UJ u z o u u z ►H N 0.8 0.6 O.k 0.2 — SOLIDS CONCENTRATION = 500 mg/1 pH = 8.00 20 ^^^^°fer^ 40 60 PERCENT SEA WATER 80 100 FIGURE 3. EFFECT OF ZINC CONCENTRATION ON UPTAKE BY SEDIMENT WITH VARYING PERCENT SEA WATER. 74 water adjusted to pH 8 o 00 o The first addition of sea water (five percent sea water content) again caused an immediate release of zinc to solution; the greatest release in terms of absolute quantity occurring, as might logically be expected, when the zinc content of the system-jwas the highest « As before, subsequent additions of sea water promoted further desorption of zinc, but the added sea water lowered the zinc concentration so that the absolute concentration of zinc in solution decreased. The theoretical maxima of zinc concentrations in solution resulting from dilution are indicated in Figure 3 The data from this series of experi- ments also have been adjusted to isolate only the effects of the added salinity, and these values, corrected for dilution, appear in Figure 4. Fit of Data to the Freundlich Adsorption Isotherm A basic assumption made throughout the reported experiments was that any portion of the originally added zinc not found in subsequent liquid samples had been bound to the soil particles in suspension. No attempt was made to quantify the percentage of zinc uptake resulting from adsorption and the percentage uptake resulting strictly from cation ex- change. However, attempts were made to fit the reported data to an adsorption isotherm. This was tried because both O'Connor (18) and Bachmann (1) have shown that zinc adsorption by suspended solids appears to follow the Freundlich isotherm, x/m = KC n . [1] In this instance x is the weight in milligrams of zinc adsorbed on ra grams of soil, and C is the equilibrium concentration of zinc in solution. The constants, K and n, are empirically derived; K depending 75 1.0 ^ 0.8 en E z> _i o (/I z 0.6 N O Z o < o u 0.4 0.2 - SOLIDS CONCENTRATION = 500 mg/1 pH - 8.00 ORIGINAL ZINC CONCENTRATION m \ .00 mg/} 20 D o.5°° mg/ - 40 60 PERCENT SEA WATER 100 FIGURE k. SALINITY EFFECT: EFFECT OF ZINC CONCENTRATION ON UPTAKE BY SEDIMENT (CORRECTED FOR DILUTION) . 76 on the units involved and, to some degree, depending on the chemical composition of the system (1) and the surface area of the adsorbent material (9) The value of n is independent of the units and depends on the nature of the adsorbent (1) and the intensity or tenacity of adsorp- tion (9) From the separate experiments the data of zinc adsorption and zinc concentration in solution were assembled and regrouped according to the percent sea water content of the reaction vessel at the time of sampling,, It was envisioned that a separate and definitive isotherm (specific values of K and n) would result for each sea water content. The regrouped data, presented as Appendix B, were fit by the method of least squares to Equation 1 in the form log x/m = log K + nlog C [2] The resulting values of K and n are given in Table 3„ A plot of several of the isotherms is shown in Figure 5. Because the six isotherms between 5 and 75 percent sea water content overlapped to a considerable extent, only the isotherms for 5 and 75 percent sea water are shown. However, the other four isotherms (for 10, 25, 50 and 66 , 7 percent sea water) fall between the two shown. The broken line in Figure 5 is the isotherm derived from all the data for 5 to 75 percent sea water, inclusive. Because the several isotherms shown in Figure 5 overlap to such an extent, only the data points for the zero percent sea water isotherm are shown. The closeness of fit of the remaining data is similar, how- ever, as may be seen by plotting the data given in Appendix B, 77 TABLE 3 FIT OF ADSORPTION DATA TO FREUNDLICH ISOTHERM Percent Sta Water K n 5.44 0.56 5 2.68 0.81 10 2.46 0.81 25 2.64 0.84 50 3.12 0.94 66.7 4.54 1.00 75 4,97 1.02 5-75 inclusive 3.02 0.86 78 10.0 E o CO is l-H UJ 5 =3 cc LU Q- a LU CO cc o CO < o z I— I M LL. o I- o < - T T 1 — — 7/ - $/ / wr 7 — 1.0 — <*/ k — - — 0.1 J ALL DATA ' x/m = FIT TO — I i 1 — 0.001 0.01 0.1 1.0 10.0 EQUILIBRIUM ZINC CONCENTRATION IN SOLUTION, C, mg/1 FIGURE 5. FIT OF ZINC UPTAKE DATA TO FREUNDLICH ISOTHERMS. 79 4. DISCUSSION OF EXPERIMENTAL RESULTS SEDIMENT CONCENTRATION STUDIES Though the general pattern of zinc adsorption and release with increasing salinity was similar among the four experiments conducted, the degree of uptake and release depended on the suspended solids content of the system (Figure 1). Prior to any addition of sea water the origi- nal 2 e mg/1 of zinc was 50 percent adsorbed by the sediment of lowest concentration and 90 percent adsorbed by the sediment of highest concen- tration. The most significant releases of zinc occurred with the first addition of sea water (5 percent sea water content). At the five percent salinity level, then, only 20 percent of the originally added 2,0 mg/1 of zinc was still adsorbed on the sediment of lowest concentration, and 75 percent of the original zinc was adsorbed on the sediment of highest concentration. Subsequent additions of sea water promoted further releases of zinc from all four slurries of sediment, though at a much reduced rate of zinc release per unit increase in salt content (Figure 2). ZINC CONCENTRATION STUDIES The pattern of zinc adsorption and release in this series of experiments was similar to that in the previous series. With a constant concentration of suspended solids in the four mixtures, the differences in zinc uptake and release resulted from differences in the initial zinc concentration (Figure 3). Prior to any addition of sea water the system containing 0.1 mg/1 of zinc yielded more than 9 5 percent of its origi- nally added zinc to sediment adsorption. Greater than 85 percent adsorp- tion of the original zinc occurred in the system containing 1.0 mg/1 of 80 zinc. With the addition of sea water to the systems, the greatest releases again occurred at the 5 percent sea water level. About 30 per- cent of the originally adsorbed zinc was released by this first addition of sea water in the system containing 0.1 mg/l of original zinc, and about 50 percent of the adsorbed zinc was released in the system contain- ing 1.0 mg/l of zinc. The concentrations of zinc in solution were again lowered significantly by dilution, the effects of which are included in Figure 3. The isolated effects of salinity, shown in Figure 4, indicate that zinc releases continue with increased salinity; but in the range of sea water contents used in this study, in no case was all the originally added zinc released to solution. Between 80 and 85 percent of the zinc originally added to the four slurries was in solution after 75 percent sea water content had been attained. 81 REFERENCES Bachmann, R, W, 1961, An experimental study of the freshwater zinc cycle. Doctoral dissertation, University of Michigan, 79 p Bauer, E, E , and T H. Thornburn, 1958, Introductory Soil and Bituminous Testing, , (Second edition). Stipes 'Publishing Co.,"" Champaign, Illinois', Carrit, D, E,, and C, E, Renn. Studies of Du Pont Spruance Plant Wastes and the James River 1951-52, The Johns Hopkins University, Baltimore. Unpublished report, Chipraan, W, A,, T, R, Rice, and T, J. Price, 1959. Uptake and accumulation of radioactive zinc by marine plankton, fish, and shellfish, U, S, Fish and Wildlife Service, Fishery Bull, 135, pp, 279-292, 5, Dion, H, G, 1944. Iron oxide removal from clays and its influence on base-exchange properties and X-ray diffraction patterns of the clays. Soil Sci ., v. 58, pp, 411-424, 6, Duke, T, W,, E, R, Ibert, and K. M, Rae, 1963. Availability of sediment-sorbed materials to marine biota. Radioecology , edited by Vincent Shultz and Alfred W. Klement, Jr., Reinhold Publishing Corporation. 7, Einstein, H. A., and R, B. Krone « 1961. Estuarial sediment transport patterns . Journal of the Hydraulics Division , ASCE , 87^ ; HY2 . pp. 51-59, 8, Friend, A, G, 1963, The aqueous behavior of strontium-85, cesium-137, zinc-65, and cobalt-60 as determined by laboratory type studies. Transport of Radionuclides in Fresh Water Systems . TID-7664, The Johns Hopkins University, Baltimore."" 9, Ghosh, S. 1963, The effect of chemical composition of ABS on adsorp- tion by soils , Sanitary Engineering Series No. 16 , University of Illinois, Urbana. 10. Grim, R. E. 1953, Clay Mineralogy : New York, McGraw-Hill Book Co., 384 p, U. Gutnecht, J, 1961, Mechanism of radioactive zinc uptake by Ulva lactuca , Limnol . Oceanog . , 6j4, pp, 426-431. 12, Gutnecht, J. 1963, Zn-65 uptake by benthic marine algae. Limnol . Oceanog . , 8jl, pp. 31-38, 13. Held, E. E. 1963. Quantitative distribution of radionuclides of Rongelap Atoll, Radioecology , edited by Vincent Shultz and Alfred W. Klement, Jr., Reinhold Publishing Corporation. 82 14, Hendricks, S„ B„ 1941 , Base exchange of the clay mineral montmoril- lonite for organic cations and its dependence upon adsorption due to Van der Waals forces „ Jour , Phys . Chemistry , 45. pp, 65-81, 15, Lowman, F G 1963, Radionuclides in plankton and tuna from the central Pacific „ Radioecology , edited by Vincent Shultz and Alfred Wo Klement, Jr , Reinhold Publishing Corporation, 16, McHenry, J, R, 1955, Adsorption and retention of strontium by soils of the Hanford project. Contract W-31-109-eng-52, HW-34499, 36 p. 17, McHenry, J, R„ 1954, (Decl, Jan, 6, 1956). Adsorption and retention of cesium by soils of the Hanford project. Contract W-31-109-eng-52, HW-31011, 41 p, 18 o O'Connor, J, T, 1961, A study of zinc in natural waters. Doctoral dissertation. The Johns Hopkins University, Baltimore, 19, O'Connor, J, T,, and C, E, Renn, 1963, Evaluation of procedures for the determination of zinc, J, Am, Water Works Assoc , 55s 5, pp, 631- 638, l 20, O'Connor, J, T,, and C, E. Renn. 1964, Soluble-adsorbed zinc equilib- rium in natural waters. J. Am, Water Works Assoc , 56:8, pp, 1051-1061, 21. Osterberg, C, J. Pattulo, and W. Pearcy. 1964. Zinc-65 in euphasiids as related to Columbia River water off the Oregon coast. Limnol. Oceanog . , 9, pp, 249-257. 1 22. Patterson, C. C, and E, F. Gloyna,, 1963. Radioactivity transport in water — the dispersion of radionuclides in open channel flow. The University of Texas, Department of Civil Engineering, Environmental Health Engineering Research Laboratory , Technical Report - 2* 23. Pritchard, D. W. 1955, Estuarine circulation patterns. Proe . Amer . Soc . Civil Engineers , Proc Vol . 81 , Separate No, 717, pp, 1-11. ! 24, Pritchard, D. W,, and A. B, Joseph, 1963. Disposal of radioactive wastes: its history, status, and possible impact on the environment. Radioecology , edited by Vincent Shultz and Alfred W. Klement, Jr, , keinhold Publishing Corporation, I 25, Rice, T. R„ 1963, Review of zinc in ecology, Radioecology , edited by Vincent Shultz and Alfred W. Klement, Jr., Reinhold Publishing Co, i 26, Robinson, B. P. 1962, Ion-exchange Minerals and Disposal of Radio- active Wastes - a_ Survey" * of" Literature . USGS Water Supply PTper 1616 . U, S, Govemment"Pnnting Office, Washington, D, C, i | 27. Rona, E., e£ al. 1962, Activation analysis of manganese and zinc in sea water, Limnol . Oceanog . , 7:2. pp. 201-206. 83 28, Sayre, W W , H„ P„ Guy, and A, R, Chamberlain, 1963, Uptake and Transport of Radionuclides by Stream Sediments . USGS Professional Paper 433-A, U, S Government Printing Office, Washington, D, C, 29, Sverdrup, H, V., M, W, Johnson, and R. H, Fleming, 1942. The Oceans - Their Physics , Chemistry , and General Biology , Prentice- Hall, Englewood Cliffs, N. J, 30, U, S, Public Health Service. 1954, Studies on the Columbia River . Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio, 31, Watson, D, G,, J J, Davis, and W. C. Hanson. 1963. Interspecies differences in accumulation of gamma emitters by marine organisms near the Columbia River mouth. Limnol . Oceanog , , 8:2, pp. 305-309 32, Watson, D, G,, J, J. Davis, and W. C. Hanson. 1961. Zinc-65 in marine organisms along the Oregon and Washington coasts. Science , 133:3467, pp, 1826-1828. 33, Watson, R. H„ 1964. Research assistant. University of Illinois, Personal communication. 84 III. FATE OF ZINC IN A SMALL STREAM The presence of bottom sediments and suspended solids in natural waters make it necessary to consider the effect of the soluble-adsorbed zinc equilibria on the dynamics of zinc equilibria on the dynamics of zinc in natural water systems. Where zinc wastes have been discharged into natural water courses, zinc has been found to disappear rapidly from solution at points downstream from the point of discharge. River silts in such areas have high zinc contents (I). Laboratory studies of the adsorption of zinc on natural river sediments have shown that adsorption is a function of pH and solids concentration (2). Since laboratory jar studies can provide only a limited amount of insight into the behavior of a metal in natural waters, stream studies were conducted involving the discharge of zinc to a small stream. During the summer of 1965, studies were made of the fate of zinc discharged to the Boneyard Creek which flows through the University of Illinois campus in Champa ign-Urbana. A weir was constructed in the stream bed for flow measurement. Planks were placed and anchored at sampling sta- tions along a 2000-foot section of the stream. A zinc chloride solution was discharged to the stream at a point just downstream of the weir to take advantage of the turbulent mixing at that point. The discharge of zinc was controlled manually to obtain an approximate average zinc concentration of 2 mg/l Zn in the stream. The zinc chloride solution was prepared in bulk so that the dis- charge of zinc to the stream could continue for 12 hours. Laboratory preparations were made to receive water samples from seven sampling stations 85 hourly. Samples were analyzed for pH and alkalinity immediately upon collection. Two al iquots of each water sample were taken for subsequent zinc analysis; one was filtered through a 0.45 u. cellulose acetate membrane filter so that filterable zinc could be determined, the other aliquot was analyzed for total zinc, At four-hour intervals, algal and bottom sedi- ment samples were collected so that the amount of zinc adsorbed or deposited on the algae and sediment could be determined. Sampling con- tinued following the period of zinc discharge for several days on a less regular schedule. Figure 1 shows the stream flow and average zinc discharge during the stream study. The stream flow varied from about 2 cfs during the day to I cfs during the early morning hours. Although it would have been desir- able to control the zinc discharge to obtain a constant average zinc dis- charge, operational difficulties interfered. As a result, the zinc dis- charge resulted in zinc concentrations ranging from 1.6 to 3.7 mg/l Zn in the stream. An indication of the variation in pH and alkalinity which occurred during the stream study can be obtained from Figure I. The values plotted are the average for all seven sampling stations. The alkalinity, which varied from 100 to 200 mg/I as CaCO. equivalent, indicates that the stream flow was derived rpimarily from ground water exf i I tration. Overall, the pH averaged around 7.5. The concentration of zinc versus distance from the point of zinc discharge is shown in Figure 2 for various times following the initiation of the discharge. The initial zinc concentration of the stream water was almost nil. For reference, the approximate average zinc discharge during 86 ALKALINITY, MG/L — ro oj o o O _o o o o 0> AVERAGE ZINC DISCHARGE, MG/L _o — ro oj J> CD 1 i i i f\) MM O // ro I "^ -^ ) /N -^ — 1 /n mm «m» m+ ^m+ COT Hi o CD REAM CO \ ° \ > f\5 "Tl r~ o JO o m oS -^ lA no O IN) i 1 1 1 ■^o — ro oj 4^ STREAM FLOW, CFS FIGURE I. Stream Flow and Average Zinc Discharge Zinc Discharge Begun At 17:40 TIME OF 87 SAMPLING 18-20 o Average Zinc Discharge [^^^^^J^^^^i^J^^i^d^miJlL^i^ i i i 'n'L^ia«i»j»t*tVl I • 1 19:20 /^ ^: :■::■::: :::;•:■:•:•:•: :;::;;:-;-: : :J ■:■:■: :•:•;•:;•;;■;•;•;•;•;•;■;•.,■.• 20:30 ^^^^jj^j^jj^^^^i^t^ • i ' ■ i • r • i • i ' • J 1000 2000 21=20 DISTANCE FROM ZINC DISCHARGE , FEET IGURE 2. Zinc Concentration vs. Distance from Point of Dischar ge 2r AVERAGE ZINC DISCHARGE 4c 3 _ — ^: ■ ■ , ■ ..:_■■ :^ ■.■■■■•■■:••.■■•■■:••■■■•■■■•:• 1 •.•■■.•:••■•.•■•.•:■:■•,•■• 1 ■■ ■ ; ■■ , ■ , ■ t ■ ; ••■■■■ j 3 r 2- 3 2 <-*»»L*^-*^ii V '• 'i • VViV.' i'li'i'- : ' I'l'.ii'i^lrtiiViViVi VVi-1 iiM'i^'-^" , 'i'Vi'^'i' , i-'r^'ri' , n'^' : \-'i''i'^'T'ti' , i' , '^^'^^'^' , ^'i'r'i'"'i'"i' - 'i' , "ii""i''i'""i'""i , 'l TIME OF SAMPLING 22:30 23:40 = 00 2:00 1000 2000 ISTANCE FROM ZINC DISCHARGE, FEET 89 AVERAGE ZINC DISCHARGE 2 .f^d^a^—Mi— ,' iiii ^i*M«^i 1 1 I I I I T I i i i , m^J M ^A*^^^M^Mii TIME OF SAMPLING 3:00 4:00 5:00 2 r ZINC DISCHARGE ENDED AT 5:35 6:00 2000 DISTANCE FROM ZINC DISCHARGE, FEET 90 TIME OF SAMPLING 7:00 9:00 13:00 '0 1000 2000 5:00 STANCE FROM ZINC DISCHARGE, FEET 91 each hour is shown on each plot. The time of flow through the 2000 foot test section of the Boneyard Creek varied with stream flow. On the average, however, the time of flow was about one hour. In many instances, the variation in the values obtained for the zinc concentrations upon replication was quite high. It became apparent, however, that the amounts of zinc found in the filtered water samples approxi- mated the amounts found in unfiltered samples. For this reason, the concen- trations of zinc computed from the analysis of both filtered and unfiltered samples and their replicates were averaged and plotted in Figure 2. The concentration of zinc shown in Figure 2, therefore, is believed to represent the total amount of zinc in the stream, essentially all of which is capable of passing through a 0.45 p, membrane filter. Each aliquot taken for zinc analysis was acidified with hydrochloric acid to minimize adsorption or precipitation of zinc during handling. Finally, zinc was determined using the dithizone compleximetric procedure described in the 12th Edition of Standard Methods (3). It appears from Figure 2 that for the first four hours approximately 60 percent of the zinc discharged to the stream disappeared almost immediately from solution, within the first 30 feet of flow. Thereafter no further decrease in zinc concentration is evident. A new pattern emerges during the second four hours of zinc dis- charge as shown in Figure 2. During that period, approximately 50 percent of the zinc disappears within thirty feet of the point of discharge. There- after, there is a more gradual depletion of the zinc concentration in the stream water with distance from point of zinc discharge. 92 As time progresses, a smaller fraction of the zinc discharged is lost from solution. This is evidenced by Figure 2 which shows the effect of the zinc discharge over the final four hours. At 4:00 a.m., for example, when stream flow is near a minimum and flow time, therefore, near a maximum, less than 40 percent of the zinc is lost from solution initially and only 50 percent is lost over the entire 2000 foot section of the stream. An important question immediately arises as to why so much zinc is lost from solution within thirty feet of the point of discharge. Dis- counting errors in the estimation of the average zinc discharge, the rapid disappearance of the zinc may be attributed to rapid adsorption on bottom sediments in the immediate region of the weir owing to the turbulence and mixing provided at that poiat. For days following the cessation of the zinc discharge, zinc was leached from the bottom sediments. The return of zinc to solution for ten hours following the end of the zinc discharge is depicted in Figure 2. A very rough estimate indicates that about 20 to 25 percent of the zinc lost from solution in the 2000 foot stream section during the zinc discharge was leached back out within ten hours after the discharge ceased. Overall, the effect of adsorption is to modify or diminish peak zinc concentrations, markedly attenuating the concentration versus time relationship downstream of zinc discharges through the mechanism of sediment adsorption. 93 REFERENCES 1. Heide, F. and Singer, E. , "The Copper and Zinc Content of the Rfver Saale," Natu rwi ssenschaf ten . 4J_, 498 (1954). 2. O'Connor, J. T. and Renn, C. E. , "Soluble-Adsorbed Zinc Equilibrium in Natural Waters," Jour. AWWA . 56, 1005 (1964). 3. A.P.H.A., Standard Methods for the Examination of Water and Wastewater, 12th Edition (1965) . 94 IV. EFFECT OF ORGANIC MATERIALS, PHOSPHATES, TIME AND ALGAE ON ZINC ADSORPTION I. Effect of Organic Materials on Zinc Adsorption Studies were made of the effect of soluble natural organic materials extracted from Illinois ground waters on the adsorption of zinc by sediments obtained from the Columbia River at Hanford, Washington. The natural organic materials were extracted from several thousand gallons of Oakwood, Illinois, ground water on a series of activated carbon columns. The adsorbed organics were eluted from the activated carbon using chloro- form and ethyl alcohol. A water phase accompanied the chloroform extract. This aqueous phase, though small in volume, contained most of the organic material extracted. A standard curve of zinc in solution versus pH was determined using distilled water with a total zinc concentration of 2 mg/l and a Columbia River sediment concentration of 1000 mg/l. Similarly, zinc adsorption was measured versus pH in sediment-water systems to which 50 mg/l of the organic extract had been added. The effect of the addition of some of the organic extracts is shown in Figure I. For comparison, the effect of adding 100 mg/l of tartaric acid, an effective metal chelate, is also shown on Figure 1. The addition of the organics is seen to decrease zinc adsorption substantially, This may be attributed either to the formation of soluble zinc chelates or to the blockage of exchange sites on the sediments by the organics. The results obtained indicate that the effect of the organic matter in altering adsorption equilibrium is minor when compared with other effects such as pH. o en M c o a. 95 PH FIG. I - EFFECT OF ORGANIC COMPOUNDS ON THE ADSORPTION OF ZINC ON SEDIMENTS 96 2. Effects of Phosphates on Zinc Adsorption Zinc adsorption was measured versus pH in sediment-water systems to which 50 mg/l of various phosphate-bearing compounds were added. The results are shown in Figure 2. Sodium phosphate exhibited little effect on adsorption whereas calcium phosphate retarded adsorption at pH less than 7. Sodium hexametaphosphate and sodium t r (polyphosphate greatly retarded ad- sorption between pH 6 and 8. The polyphosphates might be expected to have a major effect on the dynamics of zinc in natural water systems therefore. 3. Increase in Zinc Adsorption with Time In discussing zinc adsorption up to this point, we have been con- cerned with the immediate uptake of zinc which is essentially complete within a few minutes. To determine whether adsorption characteristics change over longer periods of time, sediment-water samples containing 2 mg/l of zinc were adjusted to pH values of 5.5, 6.6, 7.3, and 7.3, and stored for 20 days. An initial zinc adsorption versus pH curve was measured for reference. After 20 days, the sample stored at pH 5.5 exhibited less adsorption capacity where- as the samples stored at pH 6.6 and 7.3 indicated more adsorption capacity than the initial reference. However, the second sample stored at pH 7.3 was adjusted to pH 5.5 several hours before the adsorption curve was determined. As a result, the adsorption curve approximated the curve exhibited by the sample stored at pH 5.5 for 20 days. This result was taken as an indication that a zinc precipitate was slowly being formed at the higher pH values. Such precipitation might, in some cases, lead to the erroneous conclusion that an increase in adsorptive capacity takes place over a prolonged period of time. NJ c 01 U L. a. 91 PH FIG. 2- EFFECT OF PHOSPHATES ON THE ADSORPTION OF ZINC ON SEDIMENTS 98 4. Zinc Uptake by Algae Various investigators have been concerned with the mechanism of zinc uptake by algae. In particular, they sought to determine whether uptake was primarily related to metabolic processes or due to adsorption. Myers noted that zinc is a growth requirement for the algal species Chlorel la (7). The possibility of a metabolic uptake of zinc by algae therefore exists. However, zinc is required as a micronutrient and has been shown to be associated with various enzymes. Knauss and Porter found that various elements could be absorbed by algae (8). In studies with Chlorel la Pyrenoidosa the amount of element absorbed by the algae was found to be a function of the element and its concentration in the nutrient solution. For example, at a pH of 4.0 to 4.6, approximately nine percent of the zinc in solution was removed as a nutrient by the cells. Chipman et a]_. , uti I izing a marine phytoplankton Nitzchia closterium , 65 noted that it took up large amounts of zinc ' and apparently concentrated it, thus allowing its transfer to marine animals (9). Experiments demonstrated that much of the contained zinc of Nitzchia cells was exchangeable and thus probably unrelated to metabolic uptake. Wassermann also noted a marked cation adsorption by various species of algae (10). The spent algae could be re- generated by rinsing with IN mineral acids. Bachmann and Odum, from studies of marine benthic algae, suggested that zinc is taken up in direct proportion to the photosynthet ic rate, and i that it accumulates in the algae as a function of their growth or net pro- duction (II). These investigators observed the loss of zinc ' when the al< I I were placed in sea water and attributed it to the following mechanisms: 99 1. Physical adsorption on algal surfaces and their associated epiphytes, and 2. Actual uptake into the algal cells. Bachmann conducted other experiments in an effort to measure the 65 algal uptake of zinc (I). For this study he used Golenkinia paucispina West and West, a spherical green algae bearing numerous needle-like setae of approximately the same length as the cell diameter (lOu.). An apparent uptake of zinc due to metabolic uptake was observed by assaying samples under light and dark conditions. However, Bachmann noted that the respiratory activities of the living cells may have changed the pH of the solution sufficiently to alter the equilibrium. He also noted that the uptake of zinc increases with rising pH values and that a linear relationship is found for pH values less than 3.0, as shown in Figure I. .00/ Figure I. Relative Zinc Uptake by Living Cells of Golenkinia , Bachmann, p. 490, Radioecology. 00 Bachmann also found that the zinc uptake is dependent upon the amount and kind of suspended material, concentration of zinc in solution, and the concentrations of other cations. Further evidence for an adsorption-type reaction is the fact that for all materials listed, both living and non-living, the Freundlich adsorption isotherm was found to represent the relationship between zinc uptake and the concentration of zinc in solution. Gutknecht carried out a study of zinc uptake utilizing the algae Ulva Lactuca (12). He noted the effects of metabolism, pH, carrier ions 65 and temperature upon the uptake and accumulation of zinc by this species. He suggested that the physical process of adsorption or cation exchange is 65 primarily responsible for zinc ' uptake. The relationship between photo- synthesis and zinc absorption is primarily a secondary effect related to sur- face to volume ratio and pH. 65 Gutknecht in studies on marine benthic algae concluded that zinc uptake and loss in these littoral algae can be largely attributed to non- metabolic adsorption-exchange (13). Rowe and Gloyna stated that sorption is a function of plant growth and that photosynthetic activity is the determining factor in the uptake and 65 release of zinc '' in plants (14). This conclusion was reached after observing 65 the relative uptake of zinc ' by the water, the suspended solids, the biota and the bottom sediments in an aquarium. They postulated three possible mechanisms for the uptake of radionuclides in the ionized state by algae. 1. Adsorption of ion on cell -water interface, 2. Absorption through living membranes into the organism, and 3. Attachment of colloidal particles containing trace metal ions on external mucous coatings of aquatic organisms. 65 They also reported that zinc ' uptake is mainly a surface pheno- menon and is largely attributable to non-metabolic adsorption. After a study in a simulated stream containing biota and sediments, they surmised that when the pH, dissolved oxygen, ORP and conductivity decrease there will also be an accompanying decrease in zinc in plants. They state the following: "It is considered that the uptake of zinc by the plants is directly controlled by photosynthesis rather than the hydraulic characteristics of the stream. Thus, environmental factors such as pH, dissolved oxygen, ORP and light intensity, by their effect on photosynthesis, are related to the transport of zinc 55 " (14). Gutknecht on studies of uptake and retantion of cesium and zinc by seaweeds noted that zinc was highly concentrated by living and killed algae and by cell walls. No significant relationship between growth rate and either concentration factor or biological half-life was found among the species tested. Zinc uptake at different external zinc concentrations agreed with the Freundlich adsorption equation. Adsorption exchange appears to be an important mechanism of zinc movements in seaweeds. Thus, zinc movements involve largely adsorption exchange although the turnover is to some extent related to metabolism. As indicated by the extensive uptake by living and killed tissues and cell walls, both the cytoplasm and extracellular components 65 appear to have large numbers of potential binding sites for zinc . This might be expected since the high affinity of zinc for organic I igands is well known. In fresh water plankton and detritus the mechanism appears similar. The studies done on the uptake of zinc ' appear to be reasonably extensive and illuminating. Most of the factors which affect the uptake of zinc have been enumerated and accounted for with the exception, perhaps, of ORP. 102 All the investigators were aware of the dependency of the zinc equilibrium on pH and Bachmann, at least, performed some experiments with algae and noted the amount of zinc in solution which was present when the pH was changed over a wide range. However, it appears that in several studies of zinc adsorption on actively metabolizing algae the pH was not measured continuously, but was only measured initially. As a result, observed changes in zinc concentration were attributed to metabolic uptake although later it was realized that this "uptake" might have been due exclusively to increased adsorption with in- creased pH. However, above a pH cf 8.5 some of the apparent observed "uptake" may have been due to precipitation of the zinc as the hydroxide or carbonate. 03 REFERENCES I. 6achmar«n s R. W., Zinc ' In Studies of the Freshwater Zinc Cycle. Rad 'oecology , Re mho Id ( 1 963) . Rcwe , D. R. and Gloyna, E. F., The Transport of Zinc in an Aqueous Environment. Technical Report AEC EHE-09-6403, University of Texas (1964). 3. MC'-timer, C. M . s The Exchange of Dissolved Substances Between Mud and Water in Lakes. J. Ecology , 29(2) :280 (1941). 4. Mortimer, C H., The Exchange of Dissolved Substances Between Mud and Water in Lakes. J. Ecology , 30(1): 147 (1942). 5. Kolthoff, I. M. and Moskovitz, B., J. Phys . Chem . , 41:629 (1937). 6. Kolthoff, I. M. and Overholser, L. G., J. Phys. Chem ., 43: 767, 909 (1939). 7. Myers, J., Physiology of the Algae, Am. Rev, of Micro . , 5, 157-180 (1951). 8. Knauss, H. J. and Porter, J. W. 3 The Absorption of Inorganic Ions by Chlorel la Pyrenoidosa , Plant Physiology , 29:229-234 (1954). 9. Chipman, W. A., Rice, T. R. s Price, T. J., Uptake and Accumulation of Radioactive Zinc by Marine Plankton, Fish and Shellfish, U.S. Fish and Wildlife Service, Fisheries Bull . No. 135, Vol . 58 (1958) . 0. Wassermann, A., Cation Adsorption by Brown Algae: The Mode of Occurrence of Alginic Acid, Annals of Botany New Series , 13:79 (January 1949). II. Bachmann 3 R. W. and Odum, E. P., Uptake of Zinc and Primary Productivity in Marine Benthic Algae,, Limnology and Oceanography , 5 (October I960) ;2. Gutknecht, J., Mechanism of Radioactive Z:nc Uptake by U 1 ra Lactuca , Limnology and Oceanography , p. 426 (October 1961). p. Gutknecht., J., Uptake by Benthic Marine Algae, Limnology and Oceanography , i 8 (January 1 963) . 65 4. Rowe, D. R. and Gloyna, E. F., The Transport of Zinc in an Aqueous Environment. Technical Report AEC EHE-90-6403, University of Texas (1964). 15. Gutknecht, J., Uptake and Retention of Cs and Zn by Seaweeds. Limnology and Oceanography , 10 (January 1965). 04 V. EFFECT CF REDUCING CONDITIONS ON ZINC A DSC KPT I ON I. INTRODUCTION In natural lakes and reservoirs, the zinc concentration in the water has been reported to vary seasonally although the input of zinc to the lake remains constant (')• The magnitude and mechanism involved in this seasonal variation or cycling are not fully undersLo-;;.!. his study was undertaken to investigate the postulate that the season?! cycling of zinc is related to the cycling of iron in a lake. Since zinc always remains as a divalent cation, (Zn ), the solubility of zinc would not be expected to be a function of the oxidation- reduction potential (CRP or redox). A change in zinc equi I ibrium wi th a change in oxidation-reduction potential may be caused by one of two mechanisms. First, anaerobic bacteria which lower the ORP also produce carbon dioxide which lowers the pH. The shift in zinc equilibrium may then be caused by a change in pH produced by anerobic bacteria. Second, the solubility of iron, a divalent cation, is dependent on the oxidation- reduction potential. A change in ORP could change the amount of precipi- tated ferric oxides in the lake bottom. Since ferric oxides can adsorb heavy metals, the return of precipitated iron will decrease the adsorptive capacity of the sediment on the lake bottom. Another possible cause for a decrease in adsorptive capacity is the destruction of organic adsorbents by anaerobic decompos i t ion (I). With a decrease in adsorptive capacity due to either a decrease in the quantity of organic adsorbents or of precipitated iron oxides, the sediment would be expected to release zinc and other adsorbed cations to the aqueous phase. 105 Laboratory experiments were conducted in an attempt to observe the cycling of zinc with respect to a decrease in the adsorptive capacity of precipitated iron floe returning to solution. Other experiments such as the effect of pH on zinc adsorption by iron floe, effect of age on zinc adsorption by iron floe, and adsorption of zinc by biological growths were performed only as control groups in the study of the cycling of zinc and not as separate experiments in themselves. 2. Review of the Literature The zinc content of some natural lakes and reservoirs approaches I mg/1 , e.g. Bear Lake, Idaho, contains .65 mg/l and Lake Michigan contains from .2 to .3 mg/1 of zinc. A mean zinc content for most lakes and rivers appears to be on the order of .01 mg/1 (2). The solubility of zinc in distilled water is a function of pH and alkalinity. The solubility of zinc calculated from the solubility products [Zn^HOH'l 2 = 4.5 x lo" 7 rZn0 2 *l[H + 1 2 = 1.0 x 10" 29 is about 5 mg/1 at pH 7 and 250 mg/1 of alkalinity (12). The difference between the actual zinc content of natural waters and the theoretical solubility can be attributed, in part, to uptake of zinc by sediment. O'Connor and Renn have reported that zinc rapidly disappears, about 5 minutes, from an undersaturated zinc solution when suspended solids are present (17). The uptake of zinc in natural waters is dependent upon the amount and kind of suspended material, the concentration of zinc in solution and the concen- tration of other ions (I). Reducing conditions and pH also affect the equilibrium between zinc and suspended solids. In general, zinc adsorption 06 increases with increasing pH (3) (I). Zinc concentrations have been observed to increase with depth in stratified lakes (I). This was taken as an indi- cation that reducing conditions increase the zinc concentration in natural waters. Another indication of the effect of reducing conditions on the zinc equilibrium is that oxidized sediments take up five times as much zinc as reduced sediments (I). O'Connor, Renn and Wintner also report that reducing conditions favor a higher concentration of zinc in solution (4). 3. Iron in Natural Waters Iron may exist in water as a trivalent or divalent cation; ferric (Fell I ), the oxidized form, and ferrous (Fe II), the reduced form. The species of iron that predominates is dependent on both the pH and ox idst ion- reduction potential of the system. In general, at low pH and low ORP, the more soluble ferrous form of iron predominates, and at high pH and high ORP, the equilibrium favors the insoluble ferric form. Iron floe is formed from hydrated ferric ions as follows: rFe(H 2 0) 6 l +++ + H 2 [Fe(H 2 0) 5 0HT H ' + H 3 + 2[Fe(H 2 0) 5 (CH)l" H * rFe^H^gCOH)^"'" 4 + 2H 2 This last tetrapostive-dimeric species is the first species of a series of polymers which form iron floe. As the charge on ferric iron decreases through coordination with hydroxo groups, repulsion between ions decreases and polymerization increases. Eventually, colloidal polymers and, finally, insoluble hydrous ferric oxide precipitates are formed (5). The nature of the precipitated floe that forms is a function of pH conditions, the degree of polymerization, and the activity of other ions present. The physical 07 structure of the floe may be block shape, rod- 1 ike, or filamentous (6). Besides polymerizing with itself, iron forms inorganic complexes with fluoride, sulfate, phosphate, carbonate, and many organic compounds. If iron is oxidized by exposure to air, less than .01 mg/l of Fe , FeOH , and Fe(0H) ? remain in solution and essentially all of the suspended iron can be removed by a .45 micron membrane filter. Morgan and Stumm consider hydrous metal oxides as hydrated solid electrolytes containing a lattice structure having cation exchange character- istics resembling clay materials. With this view, the increase in exchange capacity with increase in pH is explained as an ion exchange process (7). Others (8) make a distinction between removal of cations from solution by iron floe as cop reel pi tat ion and as physical adsorption. Still others make no distinction in the removal mechanism and use the term sorption. Hutchinson reports that iron appears in natural waters in the range of .05 to .2 mg/l as ferric hydroxide, or as soluble or colloidal iron organic complexes. The vertical distribution of iron in lakes is similar to the vertical distribution of the redox potentials. The redox potential in turn is reflected by the oxygen curve. When oxidation- reduction potential is low in the hypolimnion, considerable amounts of ferrous iron will be released. If the redox potential continues to drop, hydrogen sulfide may form and the sulfide will precipitate the ferrous iron from solution (9). The exchange of dissolved substances between bottom sediments and water was studied by Mortimer. (10) (I I) . While studying the exchange of dissolved substances between mud and water in lakes, Mortimer noted that, during the winter, an "oxidized microzone 11 appeared on the surface of the 08 bottom material. This oxidized zone was from 2 to 4 cm thick. At the water-mud interface, the redox potential was the same as the potential in the overlying water. At about 2 cm, E ? (ORP at pH 7) was about +200 mv, and at 4 cm, the redox potential dropped to zero. At depths of about 4 cm or lower, the ferrous form of iron predominated, but no transfer of iron from the reduced zone to the water occured because of the oxidized microzone. During the summer months, from July through September, the lake stratified, the dissolved oxygen dropped, the redox potential dropped, and the oxidized microzone disappeared. With no oxidized zone, the ferrous iron went into solution. As much as 18 grams or iron were released per square meter; this corresponds approximately to 1.4 mg/1 if the lake were fully mixed. Before the iron returned to solution, the E_ dropped to about +180 mv. 4. Laboratory Experiments - Procedure & Materials A. General Procedure In the laboratory experiments, the following general procedures were used unless otherwise noted. Stable Zinc - A stock solution of stable zinc was prepared by dissolving .05 grams of zinc metal in concentrated hydro- chloric acid and diluting to 500 mg. This solution has a strength of I mg of zinc per 1 mg of solution. I ron Solution - A stock solution of iron was prepared by dissolving 1.78 grams of FeCI- • 4H.0 in hydrochloric acid and diluting to 500 ml. This solution has a strength of 1 mg of iron per 10 ml of solution. Al kal inity - Alkalinity was added as sodium carbonate, but expressed as calcium carbonate. Whenever alkalinity 09 was added, sodium carbonate was measured in the dry form and then added directly to the solution. 'n most of the experiments, the alkalinity is 200 mg/l as calcium carbonate; this corresponds to 212 mg/l of sodium carbonate. Zinc Determination - The radioactive zinc-65 tracer was used throughout the experiments to facilitate the determina- tion of zinc. A tracer solution was so prepared that the addition of 10 ml of tracer per liter of solution would raise the count rate of a 10 ml solution sample 2000 counts per minute above background. The amount of zinc in the tracer solution was computed as follows: Stock tracer solution = I mc/50 ml = .02 mc/ml One ml stock tracer solution added to 50 ml of water to form tracer solution used in experiments. Tracer solution ■ -^z — r— = .0004 mc/ml = .4 u-c/ml bO ml Specific activity of tracer at time of shipment «= 476 mc/gm = .47C ux/u-g Since the tracer was shipped in the fall of 1965, approximately 2 half-lives of zinc-65 tracer had elapsed. Therefore, using a specific activity of .119 nc/u.g : Zinc concentration in tracer solution = .4 u.c/ml _- , , ".". ' ft ' — 7 — = 3.36 ng/ml .19 u-c/^g I 10 In the experiments, the addition of 10 ml/1 of the zinc tracer solution increased the zinc concentration by 3.36 ng/l = .0336 mg/l . This addition of zinc was small as compared to the total zinc concentration and was neglected. Iron Determination - The general procedure for iron measure- ments is the same as that outlined in Standard Methods (25) with the exception that both sample and reagent quantities were reduced. All reagents were prepared according to Standard Methods. The procedure used for the iron deter- mination was as follows: 1. 10 ml sample placed in 50 ml flask 2. I ml concentrated hydrochloric acid added to flask 3. I ml hydroxylamine solution added to flask 4. Glass beads added to flask and flask heated to boi I ing 5. Contents cooled to room temperature and trans- ferred to a 25 ml volumetric flask 6. 5 ml ammonium acetate buffer 7. 2 ml phenanthrol ine solution 8. Dilute to mark, mix contents, and allow 10 - 15 minutes for maximum color development. The color samples were then read on a Spectronic 20 at 510 mu,. A standard curve of log transmi ttance versus concentration was prepared. pH Measurements - A Photovol t Model 180 expanded scale pH meter was used for all pH measurements. Solutions of hydro- chloric acid or sodium hydroxide were used for solution pH adjustment. II Oxidation- Reduction Potential - A Photovol t Model 180 pH meter was used for potential measurements. The instrument was equipped with an adaptor for a combination platinum- calomel probe. Filtration of Samples - Whenever a separation between the solu- tion and suspended material was made, a new membrane filter of .45 u. was used. Typically, 10 ml samples were filtered to obtain the zinc and iron concentrations in solution. Zinc - Zinc was determined by Zn tracer techniques using a gamma scintillation counter. Samples were counted for 10 minutes . Throughout the experiments, care was taken to prevent contamina- tion of the samples. Demineral ized water was used to prepare all solutions, chemicals were reagent grade, and all glassware was washed with a hydro- chloric acid solution, rinsed with tap water, then distilled water, and finally demineral ized water. B. Effect of pH on Zinc Adsorption by Iron Floe As a control measure, the effect of pH on the adsorption of zinc by glassware and by iron floe was investigated. The adsorption of zinc by glassware was observed by adding I mg/ I of zinc and 200 mg/l of alkalinity to one liter of water in a glass beaker. The pH of the solu- tion was 3.4 after only the zinc was added, and the count rate at this pH was taken to be equivalent to 1 mg/I of zinc. The alkalinity was then added and the pH was raised with sodium hydroxide. The effect of pH on zinc adsorption by iron floe was investigated by using a solution of I mg/l of zinc, 50 mg/l of iron, and 250 mg/l of alkalinity. C. Adsorption of Zinc by Iron Floe Again, as a control measure, the adsorption of zinc by iron floe was studied at pH 5 and pH 7. In these experiments, a two liter solution containing I mg/l of zinc and 200 mg/1 of alkalinity was mixed with com- pressed air at pH 7 and with air and CO- at pH 5. Iron was then added in known quantities to this solution, and then the zinc concentration of the solution filtrate was obtained after 10 to 15 minutes of mixing. The initial zinc concentration was determined at a low pH before either alka- linity or iron was added. The pH was adjusted with sodium hydroxide or hydrochloric acid. D. Artificial Lake Bottoms The artificial lake bottoms were an attempt to simulate the hypol imnion of a stratified lake. Large glass jars were used to create the artificial lake bottoms. Each jar was twelve inches deep and six inches in diameter and contained four liters of solutions. Dissolved oxygen contents similar to those encountered in natural hypol imn ions during late summer were produced by stripping the water of oxygen with compressed nitrogen and by maintaining an atmos- phere of pure nitrogen above the water surface. A plastic cover con- taining sampling holes was sealed to the top of the jar with tape. The complete removal of oxygen and the lowering of the oxidation- reduction potential was accomplished employing bacteria. After the water was stripped of oxygen, seed organisms obtained from anaerobic digester and yeast extract were added to the jar. Provisions for bubbling carbon dioxide through the jar were also provided. 113 Two jars were used in each experiment. One jar contained a sand sediment and the other jar had no sediment; all other initial conditions and additions of yeast, carbon dioxide, or oxygen were the same for both jars. The bottom sediment was 750 grams of acid-washed Ottawa silica sand that passed a #20 sieve but was retained on a #25 sieve. Throughout the experiment, the contents of these jars were not changed. In studies conducted at pH 7, the pH of each jar was readjusted to pH 7 immediately before sampling. After 14 days at pH 7, the pH of both jars were lowered using compressed carbon dioxide. At this lower pH, no pH adjustment prior to sampling was necessary. The jars initially contained 1 mg/1 of zinc, 10 mg/l of iron, and 200 mg/l of alkalinity. Yeast extract was added periodically to lower the oxidation-reduction potential by stimulating bacterial growth. Sampling consisted of recording the pH (or adjusting if necessary), recording 0RP, obtaining and filtering samples, obtaining zinc counts, and finally determining the iron content of filtered samples. Figure 3 is a diagram of a typical jar used during this experiment. E. Effect of Age on Zinc Adsorption by Iron Floe The effect of age on the adsorption capacity of iron floe was studied as a control for the artificial lake bottoms. Two experiments were run -- one at pH 7 for six days and the other at pH 5 for 9 days. In these experiments, the initial volume was two liters, zinc concentra- tion was 1 mg/l, iron was 5 mg/l, alkalinity was 200 mg/l, and mixing was accomplished by compressed air. 114 c a do Sampling Hole &MH> KJ \J Iron Floe Sediment / //////// J To pH £• E h Meter Figure 3 Diagram of Apparatus 115 F. Adsorption of Zinc by Biological Growth Again, as a control, the adsorption of zinc by the bacteria used for producing reducing conditions was investigated. A jar similar to those used for the artificial lake bottoms, had been used to acclimate the anaerobic bacteria to the yeast extract. This jar had received yeast extract for about a month before the experiment started. A known quantity of zinc was then added to this jar, and the amount of zinc remaining in solution was then recorded over a period of days. The amount of bacteria in this jar is not related to the amount of bacteria in the artificial lakes, but was of the same order of magnitude. 5. Results and Discussion A. Effects of pH on Zinc Adsorption by Iron Floe Without knowledge of the adsorption capacity characteristics of the glass container, the adsorption capacity reported for sediments or iron floe could be misleading. The adsorption characteristics for the glass breaker containing 200 mg/l of alkalinity and 1 mg/l of zinc are given in Table 1 . When pH 8.23, is exceeded, the decrease of zinc in solution is ! attributable to the precipitation of zinc as Zn(0H) ? . From theoretical consideration of solubility products, zinc is soluble in excess of 1 mg/l when the pH is less than 7.5 and alkalinity is 250 mg/l (4). For the data given, zinc is lost from solution even in the pH range 5.40 to 7.14. This may be attributed to adsorption by the glassware. In general, as long as the pH is lower than 7.5, zinc adsorption by the glassware might be ex- pected to be on the order of 10 - 15 percent. Table I Zinc in Solution Versus pH J3H Zinc in Solution - mg/1 3.40 1 5-40 • 97 6.02 • 90 6.66 .77 7-14 .81 7.61 • 70 8.23 .86 8.55 .45 9.10 ,31 Table 2 Effect of pH on the Adsorptive Capacity of Iron Floe -EM Zinc in Solution - mpj/1 5.4 .88 5.7 .79 6.0 .62 6.1 .65 6.4 • 45 6.8 .22 The effect of pH on the adsorption capacity of bottom sediments has been reported to be very significant by many investigators. Similarly, a change in pH would be expected to affect the adsorptive capacity of iron floe. The results obtained from a solution containing I mg/l of zinc, 50 mg/l of iron, and 250 mg/l of alkalinity is given in Table 2. This data demonstrates the dependence of the adsorption capacity of iron floe on pH. Control of pH is very important in the study of zinc adsorption by iron floe. B. Adsorption of Zinc by Iron Floe In the artificial lake bottoms, precipitated iron will be released to the solution. When this happens the amount of precipitated iron and hence the adsorptive capacity of the bottom material will be decreased and zinc will be released to solution, the adsorptive capacity of the sediment or iron floe must be less than that required to adsorb most of the zinc. To determine this relationship, the adsorptive capacity of iron floe was determined at pH 7 and pH 5. In both experiments, the initial zinc was I mg/l and alkalinity was 200 mg/l. The results are given in Table 3 for pH 7 and in T?ble 4 for pH 5. From the data in Table 3, it appears that nearly all the iron must go into solution before appreciable amounts of zinc are released in solution. From Table 4, more than three mg/l of iron must be precipitated before a significant amount {20 percent) of zinc is adsorbed. These observations were useful aids in interpreting the results from the artificial lake bottoms. I 18 Table 3 Adsorption Capacity of Iron Floe for Zinc at pH 7 Iron (mq/1) Zinc in Solution (mq/1) 1 2.5 • 312 5 .192 7-5 .11 10 .05 Table k Adsorption Capacity of Iron Floe for Zinc at pH 5 Iron (mq/1) Zinc in Solution (mq/1) 1 1 .815 1.5 .819 2 .910 2.5 .870 3 .855 k • 795 5 .758 6 .686 10 .630 15 • 577 I 19 C. Artificial Lake Bottoms The first attempt (pH 7) to observe the cycling of zinc by varying the amount of iron precipitate did not show any significant cycling as shown in Figures 4 and 5. In the artificial lake bottom that had no sediment (pH 7), the iron slowly began to return to solution, but the amount of iron that remained precipitated (6.5 mg/l) had more than enough adsorptive capacity to prevent the zinc from returning to solution. The same is also true for the jar containing the sediment. From Figure 2, it appears that the Eh of the system must be below +200 mv before iron begins to return to solution. In both jars at pH 7, the Eh remained below +200 mv for five days. The iron in the jar with no sediment was returning slowly to solution; while in the jar with sediment, no return of iron was noted. A possible cause for no zinc return and for little or no iron return could stem from the unstable pH conditions. Before each run, the pH was adjusted to 7.00 + .05. The pH was always initially above 7. In the jar containing sediment, the initial pH increased to 8.3 on one day, and in the jar without sediment the pH climbed to 7.5. The drift in pH was believed to be due to stripping with nitrogen. Precipitation of zinc may have occurred at high pH as well as the precipitation of iron carbonates and oxides. To stabilize the pH and to avoid possible precipitation of zinc, the pH of these two jars were then lowered with compressed carbon dioxide. The results of this change is shown on Figures 6 and 7. In both cases, con- siderable amounts of iron went into solution. The return of iron to solution in the artificial bottom containing sediment shows a good relationship 20 LD .4 .2 -.2 -.4 E E N .8 .6 .4 .2 t 1 1 r Reducing Conditions 8 L I \- I +- I rr 10 mg/1 of Iron Added L I \- 1 mg/1 of Zinc Added L J L_l 1—2 L 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Days Figure 4 Artificial Lake Bottom - No Sediment - pH 7 Iron and Zinc in Solution 12 .4 o > -.2 -.4 Reducing Conditions J L J L J L E 10 mg/1 of Iron Added N .8 .6 .4 I I- I .2 4. \. 1 mg/1 of Zinc Added 1 7T JL 10 11 12 13 14 15 Days Figure 5 Artificial Lake Bottom - Sediment - pH 7 Iron and Zinc in Solution J I L J L Reducing Conditions J L J I I L J L 122 J I < 10 mg/1 of Iron Initially _o- J L J I I L J L )£ 1 mg/l of Zinc Initially jO- o o ft o o J L K J L 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 Days Note: Sys tern aerated on the 13th day. Figure 6 Artificial Lake Bottom - No Sediment - pH 5 Iron and Zinc in Solution 23 el 5 u J I ^— 2 o o 2. J I I I L n o. i ' i Reducing Contitions -L J I L J L J I J I I L 10 mg/1 of Iron Initially o J I L J I L 1 1 mg/1 of Zinc Initially •XT ■o- -£L J L 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Days Note: System aerated on the 13th day. Figure 7 Artificial Lake Bottom - Sediment - pH 5 Iron and Zinc in Solution 24 between iron in solution and Eh. The Eh for return of iron to solution appeared to be about +400 mv at pH 5. In both cases at pH 5, three mg/l or less of precipitated iron remained in the system. From Table 4, about .8 mg/l of the zinc should be in solution. The reason for more zinc not returning to solution is attributed to zinc adsorption onto the biological growth. After thirteen days, the system was aerated. The pH of both systems rose to around 6.0, the iron in solution decreased, and the zinc in solution decreased. This decrease in zinc can be attributed to adsorp- tion onto the 7 or 8 mg/l of newly formed iron precipitate or to increased adsorption at the higher pH. From Table 4, 8 mg/l of iron floe are capable of adsorbing .7 mg/l of zinc. D. Effect of Age on Zinc Adsorption by Iron Floe As another control to aid in the understanding of the adsorption of zinc by iron floe, the change in adsorptive capacity of floe with time was studied at pH 5 and 7. The data obtained from experiments using I mg/l of zinc, 5 mg/l of iron, and 200 mg/l of alkalinity as in Tables 5 and 6. In both cases of aging the iron floe, little differences of zinc in solution resulted. At pH 7, the zinc concentration remained at about .18 mg/l, and at pH 7, the zinc remained near .8 mg/l. In general, no significant increase or decrease in the adsorption capacity of zinc was noted for the period of time studied. E. Adsorption of Zinc by Biological Growth Since the amount of zinc in solution in the artificial lake bottoms at pH 5 was less than expected, the possibility of adsorption by 125 Table 5 Change in Adsorption Capacity of Iron Floe With Time at pH 7 Time £ hr. £ hr. 3 A hr. 1 hr. 2 hr. 5 hr. 1 day 2 days 6 days Zinc in Solution .10 .12 .21 .16 .24 • 15 .16 .17 .20 Table 6 Change in Adsorption Capacity of Iron Floe With Time at pH 5 Time 1 days 3 days k days 5 days 9 days Zinc in Solution • 73 .84 .85 •77 .87 26 the bacteria was considered. Although the amount of biological growth in this experiment is not the same as the growth in the artificial lakes, the significance of the amount of zinc adsorbed by the bacteria is shown in Table 7. Table 7 Zinc Uptake by Biological Growth Time (d ays) Zinc in Solution (mg/l) pH .67 5.90 1 .65 5.72 5 .54 5.60 6 .44 5.48 7 .55 5.52 11 .31 5.55 The initial zinc concentration was 1 mg/l . The mass of sus- pended solid in this system was 130 mg/l of solids dried for 24 hours in a desiccator. Although the quantity of yeast extract added to this jar is unknown, the total amount of yeast extract added to this system was less than the amount added to the artificial lake bottoms. 127 REFERENCES 1. Bachmann, R. W. , 1961, Zinc-65 in Studies of Freshwater Zinc Cycle, Rad ioecoloqy , Chapman and Hall, Ltd., London. 2. Livingstone, D. A., 1963, Data of Geochemistry-Chemical Composition of Rivers and Lakes, Geological Survey D rofessional Paper 440-6, U. S. Government Printing Office. 3. C'Connor, J. T. , and C. E. Renn, !964, Soluble-Adsorbed Zinc Equilibrium in Natural Waters, Journal American Water Works Association , 56;8. 1. Renn, C. E. , J. T. C'Connor, and I. Wintner, 1962, A Study of Silt Adsorption of Radioactive Zinc and Iron, Sanitary Engineering and Water Resources, John Hopkins University. 5. Stumm, W.and J. J. Morgan, 1 962, Chemical Aspects of Coagulation, Journal American Water Works Association , 54:8. 6. Feitknecht, W. , 1959, Iron Hydroxides, Z. Electrochemistry , 63:34. 7. Morgan, J. J., and W. Stumm, 1965, The Role of Multivalent Metal Oxides in Limnological Transformations, £s Exemplified by Iron and Manganese, Harvard University, Sanitary Engineering, Reprint No. 75. 8. Kolthoff, I. M., and B. Moskovitz, 1937, Studies on Coprecipi tation and Aging, Journal Physical Chemistry , 41:629. 9. Hutchinson, G. E. , 1957, A Treatise on Limnology , Vol. 1, Geography, Physics, and Chemistry, John Wiley and Sons, Inc., New York. 10. Mortimer, C. H., 1941, The Exchange of Dissolved Substances Between Mud and Water in Lakes, Journal Ecology , 29:2. M. Mortimer, C. H. 1942, The Exchange of Dissolved Substances Between Mud and Water in Lakes, Journal Ecology , 30:1. APPENDIX I SUMMARY OF DATA ON THE OCCURRENCE OF STABLE AND RADIOACTIVE ZINC AND COBALT IN THE AQUATIC AND TERRESTRIAL ENVIRONMENTS AI-2 LITERATURE REVIEW Part of the first objective in this study was to obtain, by an extensive literature search, a knowledge of the occurrence of stable and radioactive zinc and cobalt in the aquatic and terrestrial environments. The data compiled during this literature review are presented as an Appendix. The data are divided into four separate sections, based on the geographical location of the samples. Tables A-l and A-2 consist of data obtained from the analysis of samples taken in the Columbia River area. Table A-3 summarizes analyses of samples taken in the Thames River, Connecticut area. Tables A-4 and A-5 report results obtained in the South- west Pacific area, and Table A-6 contains the data found for all areas not included in the preceding tables « Each table is divided, where data are available, into two major sections, "Aquatic Environment" and "Terrestrial Environment o " Within each section, the data are tabulated as to sample type in a general order of increasing physical or biological complexity . Thus a typical table begins with data concerning water and ends with data concerning either fish, if in the aquatic environment section, or man, if in the terrestrial environment section,, A complete list of the sources of information for this data is included in the references section following Table A-6„ Additional references which do not contain specific quantitative data, but are of general interest, are included separately „ The quantitative data in these tables should be related to allowable concentrations of these radionuclides in particular types of samples, Eisenbud (4) states that the United States Atomic Energy Commis- sion's recommended limits (1961) are: A 1-3 Zinc i 3000 pc/g occupational limit and 100 pc/g non-occupational limit, in water; U00 pc/g in seafood when the population obtains half its protein requirement from seafood „ fin Cobalt i 1000 pc/g occupational limit and 50 pc/g non-occupational limit, in water; 100 pc/g in seafood when the population receives half its protein requirement from seafood » The recommended limits provide a basis for understanding the significance fi S fiO of the concentrations of Zinc and Cobalt reported in the tables. It should be recognized that data on radioactivity are most abundant in locations where a possible radiation hazard exists „ The con- centrations of radioactive zinc and cobalt in environmental samples do not, therefore, represent normal conditions. The concentrations of stable and radioactive zinc and cobalt have been reported in the literature in several types of units „ Where possible, data in the tables have been converted to ppm (parts per million) or pc/g -12 (pico 0.O ) curies per gram). Weights have been recorded as either wet, dry or ashed, whenever these data were given in the literature „ Thomas et al » (28) has provided the following relationships between dry and wet weights for environmental samples , as dry weight to wet weight ratios : "Fish s 10 samples; range ,162 to 262; ave„ »200 Plants: 9 samples; range ,081 to 0*402; ave ,215 Invertebrates: 8 samples; range 125 to o515; ave„ „238," COLUMBIA RIVER AREA Tables A-l and A-2 contain data concerning the Columbia River area, Table A-l is a brief summary of the results of very extensive monitoring of the Hanford area and downstream along the Columbia River, by the Hanford AI-1 I staff o Table A°2 includes a broader range of sample types, but the sampling Additional Data - Qualitative and Quantitative 65 Pritchard and Joseph (1961) (20) found that Zinc ' was the most abundant radionuclide found in shellfish near the mouth of the Columbia River, and that it showed a marked decrease with distance seaward from the mouth of the Columbia River for both shellfish and plankton s Osterberg et al (1964) (18) reported that samples of euphausiids collected in the Pacific at Newport, Oregon, contained an average of 65 UoO pc/g dry weight of Zinc , and that background activities along the Pacific coast of Alaska and California showed 1„0 to loM- pc/g dry weight of c c Zinc in this organism „ The authors continues 65 "High Zn ' values near the mouth of the Columbia River in spring and somewhat increased values in the fall correspond roughly to spring and fall plankton "blooms ," The euphausiid studied, Euphausia pacifia , grazes on phy top lank t on o o from which it appears to obtain Zn^5 0<)<) fresh water and marine diatoms reach equilibrium with reactor effluent water rapidly, in a few hours „ Euphausiids require a much longer period for maximum concent rat ion „ " Foster (1963) (6) states s 65 "Zn ' is the only radionuclide of reactor effluent origin which has been found in sufficient abundance beyond the mouth of the Columbia to be of radio- logical interest o The oyster has been found to contain more Zn*>5 than other seafood organisms ," Watson et al . (1961) (29) found, in addition, that the highest 65 levels of Zinc " were found in plankton, algae and mollusks and that of the human foods, oysters exhibited the highest levels s "In these marine organisms, Zn v was responsible for up to 40% of the total radioactivity „ „ „ This radionu- clide is present in Hanford reactor effluents and is one of the dominant radioisotopes in aquatic organisms inhabiting the Columbia River downstream from the Al-5 reactors „ o oConcentrat ion of Zn in crabs, fish and marine birds is approximately one-tenth that found in algae and mollusks (in samples from the Oregon and Washington coasts)," Palmer (1958) (19) found that rats exposed to concentrated 65 Hanford reactor effluent for one year contained a concentration of Zinc in the skeleton and soft tissue that was higher than any other radionuclide , Silker (1964) (25) measured the concentrations of zinc and cobalt in Columbia River water just upstream of the Hanford reactors „ Samples were taken during the period from January 5 to August 17, 1962, Zinc con- centrations ranged from 2,4 to 37 „ 6 ppb and cobalt concentrations ranged from oOOl to „087 ppb, during this period , THAMES RIVER, CONNECTICUT, AREA Table A-3 contains data concerning the Thames River, Connecticut, area,, Of particular interest in this table is the graphic result of a study by Skauen (1964) (26) of the effect of nuclear submarine activities on the . 65 Zinc concentration in oysters harvested from the Thames River near the submarine base. Whenever a submarine docked for an extended period, it would shut down its power reactor „ The reactor cooling water decreased slightly in volume as the water temperature decreased. Before starting up the reactor for another voyage, the reactor cooling water was "topped up" to produce correct operating characteristics within the power reactor system, However, as the reactor began to operate, the temperature of the cooling water increased, with a corresponding increase in volume, with the result that the excess few gallons of contaminated water was discharged into the river. It appears, from the table, that this practice was corrected by July 10, 1961, AI-6 SOUTH-WEST PACIFIC AREA Tables A-4 and A- 5 contain data concerning the South-West Pacific area Table A-4 summarizes the extensive monitoring of this area following the "Redwing" shot series of 1956, as reported by Thomas et al , (1958) (28), Table A- 5 provides additional data concerning this geographical area, Additional Data - Qualitative and Quantitative Watson et al , (1961) (29) stated that! "Zn65 t a nonfission product commonly formed by nuclear detonations and nuclear reactors , was found in pelagic fish collected in 1954 near the Pacific Proving Grounds after the 'Castle' series of weapon tests „ It was subsequently reported in tuna, marine plankton, mollusks and reef fishes of the western Pacific , In these marine organisms, Zn 6 ^ was responsible for up to 40% of the total radioactivity and in most instances was more abundant than any of the fission products," Held (1961) (10) reported that five years after contamination with radioactive fallout which occurred due to a detonation at Bikini Atoll in 1954, Zinc and Cobalt were found to be the most abundant radionuclides in marine organisms, and in man, as a result of the consumption of marine 1 organisms. Birds which fed almost exclusively on marine organisms contained mainly Zinc , Zinc ' predominated in fish, with Cobalt present as well, 54 57 60 65 90 Marine invertebrates contained Manganese , Cobalt * , Zinc , Strontium 144 65 60 and Cerium , with Zinc and Cobalt most prominent. Corals contained : Cobalt . Clams contained mostly Zinc ' and Cobalt * , Plankton con- tained Manganese , Cobalt * , Zinc , Zirconium , Ruthenium and 144 Cerium , ail in minute amounts , Marine algae contained principally Cerium 144 , Thomas et al, (1958) (28) noted that following the "Redwing" shot series of 1956, Cobalt and Manganese were the predominant radionuclides AI-7 65 ... in clams, Zinc ' was the major radioisotope in fish specimens, and radio- active cobalt, manganese and zinc were the most universally detected radionuclides with respect to all sample types » The Cobalt concentration in livers of clams increased for about ten months after the first shot of the series, peaked at about 80 pc/g, then rapidly decreased. Cobalt was also found in clam mantle, gonad and muscle, but at lower concentrations 6 S Zinc s followed the same pattern, peaking at about 8 pc/g The authors concluded that the concentrations of Cobalt and Zinc ' for whole clams would be about 20 to 25 percent of that of clam livers for the same sample „ Donaldson (1961) (3) reported, with reference to the Eniwetok test site, that! "Available substances are rapidly taken up by the biota „ Plankton acquire radioisotopes by absorption, adsorp- tion, or botho The major initial concentration of radioactive isotopes probably occurs in the phytoplank- ton and includes Zn 6 $ (12 to 47%), Co 57 t 58 » 60 (11 to 50%), Fe 55 * 59 (1 to 40%) and Zr 95 -Nb 95 (3 to 44%)„ "The herbivorous and omnivorous fish tend to concentrate the same isotopes found in plankton „ Zn^5 accounts for more than 50% of the total radioactivity in the organs of these fish and Fe^5»59 comprises a major part of the remaining activity The radioactive isotopes of cobalt account for 7 to 20% of the radioactivity „ "The carnivorous fish such as tuna and bonito (mackeral), caught in the open ocean, contain Zn 6 ^ at the highest levels of any of the three groups of fisho Zn^5 accounts for 75 to 92% of the total radioactivity; Fe 55 » 59 for 6 to 25% and the cobalt radioisotopes for 1 to 3% " Lowman (1961) (13) observed in sea water contaminated with fission products and neutron induced radionuclides that Zinc ' at 48 hours after a detonation accounted for only 02 percent of the activity in water samples, and that by the end of six weeks accounted for 84 percent of the activity « However, in plankton samples, at 48 hours, the Zinc ' accounted for per- cent of the total radioactivity while at the end of six weeks, it accounted for 25 o0 percent of the total activity . Iron * and Cobalt • • AI-8 65 :cur in concentrations almost identical with Zinc , in each of these two >es of samples, at each sampling time,, The author comments: "Plankton exhibit high concentration factors for a few elements of which cobalt is one. Since plankton only equal about 1 ppm by weight in sea water, thus they contain only a small fraction of the total activity o o oConcentrat ion factors exhibited by plankton for cobalt are 100,000 at six weeks," In the food chain of water to plankton to omnivorous fish to C"7 CO Cfl ^nivorous fish, Lowman found that discrimination against Cobalt * was progressive throughout the trophic levels, A large percentage of the 65 total radioactivity in the carnivorous fish was due to Zinc „ In the food chain of water to plankton to omnivorous fish to birds, the birds did not retain significant amounts of radioisotopes of cobalt, but did retain a 65 ma] or part of the ingested Zinc Rowe and Gloyna (1964) (23) found from a review of the literature that: 65 "The mean level of Zn in 200 male, adult Marshallese in 1959 was 9,400 wyc/kg (9,4 pc/g) of body weight, or about 100 times that of an inhabitant of the United States o The exposure was the result of seven series of tests involving the detonation of 59 nuclear devices by the United States in the Marshall Islands between July, 1946, and July, 1958 " OTHER AREAS Table A-6 contains data for samples obtained from many areas of the world, but excluding the Columbia River, the South-West Pacific and the Thames River, Connecticut areas „ Additional Data - Qualitative and Quantitative Lomenick et al„ (1963) (12) determined the concentrations of Al-9 60 Cobalt in the White Oak Creek drainage basin , This basin was used from 1943 to 1955 as a final settling basin for low-level radioactive wastes discharged from the Oak Ridge, Tennessee, reactors and laboratories. The detention provided by the impoundment furnished some dilution and a period of decay for short-lived radionuclides before release to the Clinch River. It also resulted in deposition and accumulation of contaminated sediments. In samples taken in 1962, the authors found that the layer of sediment extending from to 6 inches below the surface contained 119 curies of Cobalt , the layer from 6 to 12 inches contained 22 curies, the layer from 12 to 18 inches contained 8 curies , and the layer from 18 to 24 inches 60 contained 3 curies, for a total of 152 curies of Cobalt , A preliminary survey of the creek bed and its flood plain revealed that bottom sediments to a depth of 18 inches, 2,3 miles downstream from the source of contami- 60 nation, contained Cobalt in concentrations of 290 to 2200 pc/g dry 60 weight. Cobalt was the major radionuclide present in these sediments. CT\ AI-10 en ■ V v V C u > 11 ii- i3 £i c — ' TJ C u Q U 01 c •a _, m X cc a' 4- ai 2 c 4-1 (U •- 2 4J It! 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[j i S 8 s 8*s s < 3 J 3 3 : HI H n HI HliHlJii i 5 ki SSI : i I- Al-27 REFERENCES FOR APPENDIX Notes Abbreviations Used for Technical Reports A/Conf t 15 ; Proceedings of the Second International Conference , United Nations Peaceful Uses of Atomic Energy, Geneva, 1958 DPSPU: U, S» Atomic Energy Commission Technical Reports HW and HW-SA ; U, S, Atomic Energy Commission Technical Reports; Hanford Atomic Products Operation, General Electric Company, Richland, Washington LAMS ; Los Alamos Scientific Laboratory of the University of California Technical Reports NP: U. S. Atomic Energy Commission Technical Reports ORNL : U. S. Atomic Energy Commission Technical Reports; Oak Ridge National Laboratory, Oak Ridge, Tennessee RADIOECOLOGY : Proceedings of the First National Symposium on Radioecology held at Colorado State University, Port Collins, Colorado, September 10-15, 1961. U. Shultz and A. W„ Klement eds„, Reinhold, New York and The American Institute of Biological Sciences, Washington, D. C. 7«+6 pp. (1961) TIP ; U, S. Atomic Energy Commission Technical Reports USNRDL ; U, S. Atomic Energy Commission Technical Reports UWFL ; U. S. Atomic Energy Commission Technical Reports; Applied Fisheries Laboratory, University of Washington, Seattle, Washington Wj U. S, Department of Health, Education, and Welfare, Public Health Service; The Robert A, Taft Sanitary Engi- neering Center Technical Reports, Cincinnati, Ohio c c 1. Bachmann, R. W„ , "Zinc s in Studies of the Freshwater Zinc Cycle," Radioecology . pp. 485-<+99 (1961) 2. Barranik, P. I,, e£ al . , "Zinc, Manganese, Cobalt and Iodine in the Drinking Water from the Artesian Wells of Kiev," Gigiena i Sanit , 26, pp. 95-96 (1961) 3. Bondarenko, G, P., "Seasonal Dynamics of Mobile Forms of Trace Elements and Iron in Bottomland Soil of the Ramenskoe Widening of the Moscow River," Nauchn. Dokl. Vysshei Shkoly , Biol. Nauki , 1962, 4, pp, 202-207 (1962) Al -28 4. Brown, W. H., and Fulton, R. B. t "Metal Content of Mine Waters," Symposium of Geochemical Prospecting, I„, Congr, Geol. Intern,, 20th, Mexico City, 1956, pp. 189-197 (1958) 5. Carritt, D„ E , et al., "Studies of DuPont Spruance Plant Wastes and the James River, 1951-52," 44 pp. plus tables (1952, unpublished) 6. Chipman, W. A., Rice, T, R, , and Price, J, J,, "Uptake and Accumulation of Radioactive Zinc by Marine Plankton, Fish and Shellfish," U. S. Fish and Wildlife Service, Fishery Bulletin, 58 , pp. 279-292 (1958) 65 7. Cohn, S. Ho, Love, R. A., and Gusmano, E. A., "Zinc ' in Reactor Workers," Science , 133 , pp. 1362-1363 (1961) 8. Cowser, K. E., Snyder, W. S., and Cook, M. J,, "Preliminary Safety Analysis of Radionuclide Release to the Clinch River," TID-7664, pp. 17-38 (1963) 9 Davis, J. J., "Accumulation of Radionuclides by Aquatic Insects," HW-SA- 3050, 13 pp. (1963) 10, Davis, J, J., Hanson, W G,, and Watson, D. G., "Some Effects of Environ- mental Factors upon Accumulation of World Wide Fallout in Natural Populations," Radioecology , pp. 35-38 (1961) lie Davis, J. J., et al., "Radioactive Materials in Aquatic and Terrestrial Organisms Exposed to Reactor Effluent Water," United Nations Peaceful Uses of Atomic Energy-Proceedings of the Second International Conference, Geneva, September, 1958, pp. 423-428 (1958) 12, Eisenbud, M., Environmental Radioactivity , McGraw-Hill, 430 pp. (1963) 13. Fabricand, B. P., et al., "Trace Metal Concentrations in the Ocean by Atomic Absorption Spectroscopy," Geochem Cosmochin. Acta , 26, pp. 1023- 1027 (1962) 65 14. Fitzgerald, B. W , Rankin, J. S«, and Skauen, D. M. , "Zinc Levels in Oysters in the Thames River (Connecticut)," Science , 135 , p, 926 (1962 — notes not 1961 as listed in tables) 15. Folsom, To Ro , and Mohanrao, Go J., "Behavior and Significance of Certain Radioactive Isotopes Found in Sewage-Treatment Plants of Various Cities, II o Short-Term Variation and Behavior of Certain Gamma Activities in the Hyperion Treatment Plant," TID- 16466, Pt, B,, 54 pp (1962) 16. Folsom, To Ro , et alo , "A Study of Certain Radioactive Isotopes in Selected Waste Treatment Plants," Journal Water Pollution Control Feder- ation . 35, pp, 304-333 (1963) |17. Foster, R. F. , "Concentration of Radionuclides in Columbia River Water at Hanford and Pasco, 1963," Private Correspondence, 2 pp, (1964) i |18. Foster, R, F, , et al . , "Evaluation of Radiological Conditions in the Vicinity of Hanford; Apr -June, 1963," R, H Wilson, ed,, HW-78395, J 28 pp, (1963). AI-?< 19 Foster, R F , et al , "Evaluation of Radiological Conditions in the Vicinity of Hanford for 1962," R, H, Wilson, ed , HW-76526, 183 pp. (1963) 20, Foster, R F , et al , "Evaluation of Radiological Conditions in the Vicinity of Hanford for 1961," I, C„ Nelson, ed,, HW-71999, 217 pp, (1962) 21. Foster, R, F,, et al_, , "Evaluation of Radiological Conditions in the Vicinity of Hanford for 1960," I, C, Nelson, ed , HW-68435, 109 pp, (1961) 22 o Gericke, S , "Effect of Thomas Phosphate on the Cobalt Content of Meadow Hay," Phosphorsaeure , 22 , pp, 48-60 (1962) 23, Glebov, F M. , and Kozarezenko, P, M,, "The Contents of Microelements in the Water of Springs in and Around Kharkov," Mater ialy Nauch, Konfo Sanit ,-Gigien, Fak, Khar'kov, Med Inst,, Posvyashchen, 40-Letiyu Velikoi Oktyabr Sots Revolyutsii, Sbornik, 1958, pp, 45-46 (1958) 24, Glebov, F M, , and Kozarezenko, P, M, , "The Content of Copper and Zinc in Mineral Waters of Berezovo and Mirgord," Materialy Nauch, Konf, Sanit ,-Gigien, Fak, Khar'kov, Med Inst,, Posvyashchen, 40-Letiyu Velikoi Oktyabr Sots Revolyutsh, Sbornik, 1958, pp„ 47-48 (1958) 25, Gutknecht, J„, "Zn Uptake by Benthic Marine Algae," Limnology and Oceanography , £, pp, 31-38 (1963) 26, Hanson, W, C, et al , "Radioecology Studies in Northern Alaska," hw-sa- 3050, io pp^iges) 27, Harvey, R, S,, "Uptake of Radionuclides by Fresh Water Algae and Fish," DPSPU- 63-30-3, 11 pp, (1963) 28, Hayakawa, T,, "Amounts of Trace Elements Contained in Grass Produced in Japan," Natl, Inst, Animal Health Quart, 2 , pp, 172-181 (1962) 29, Hayashi, A,, "Biochemical Studies on the Trace Elements in Ostrea gigas , II, Distribution in Different Parts of Meat," J, Sci. Hiroshima Univ , I Ser, A-II , 25_, pp, 347-350 (1961) 30, Healy, J, W, , et al,, "Radiation Exposure to People in the Environs of a Major Production Atomic Energy Plant," United Nations Peaceful Uses of Atomic Energy-Proceedings of the Second International Conference, Geneva, September, 1958, 18, pp, 309-318 (1958) 31 • Heide, F, , and Singer, E,, "The Copper and Zinc Content of the River Saale," Naturwissenschaf ten , 41 , pp, 498-499 (1954) 32« Hutchinson, G, E,, A Treatise on Limnology , John Wiley and Sons and New York, 1015 pp, (1957) i 33, Junkins, et al , "Evaluation of Radiological Conditions in the Vicinity I of Hanford for 1959," HW-64371, 123 pp, (1960) A I -30 34, Kaye, S„ V,, and Dunaway, P B„, "Estimation of Dose Rate and Equilibrium State from Bioaccumulation of Radionuclides by Mammals," Radioecology , pp, 107-112 (1961) 35 » Kehoe, R A„ , Cholak, J., and Largent, E„ J., "The Concentrations of Certain Trace Metals in Drinking Water," Journal American Water Works Association , 36 , pp„ 637-644 (1944) 36. Kiermeier, F« , and Winkelman, H,, "Determination and Occurrence of Cobalt in Cow Milk," Z, Lebensm-Untersuch. U.-Forsch , 115 , pp. 309-322 (1961) 37. Koval'skii, V. V„, and Letunova, So V,, "The Role of Phyto and Zooplankton of Water Bodies in Cobalt Migration," Zool. Zhur , 40 , pp, 809-817 (1961) 38. Krainov 9 S. R, , "New Data on Mineral Waters of the Marittime Territory," Byul. Nauchn.-Tekn. Inform. Min, Geolo 1 Okhrany Nedr SSSR 1961 , 2, pp. 19-23 (1961) - 39. Kreiger, H, L,, Gilchrist, J„ E , and Gold, S , "Concentration of Radio- activity and Detection of Cobalt 60 and Zinc 6 ^ i n Rainout," Talanta , 6, pp. 254-264 (1960) 40o Kuroda, K / B1. Chem. Soc Japan , 15 , pp 88-92 (1940) 41. Lifshits, Go Mo, "Trace Elements in Underground Waters of the Voronezh Region," Tr Voronezhsko Zoovet. Inst, , 17 , pp 101-109 (1961) 42. Lifshits, Go M , "Trace Elements in Waters of Certain Rivers of the Voronezh Region," Tr Voronezhsko Zoovet , Inst , 17 , pp. 111-117 (1961) 43. Lomenick, T F , et^al,, "Study of White Oak Creek Drainage Basin," ORNL-3492, pp 51-62"Tl963) 44. Lowman, F Go, "Radionuclides in Plankton and Tuna from the Central Pacific," Radioecology , pp» 145-150 (1961) 45. Lowman, F G , "Iron and Cobalt in Ecology," Radioecology , pp 8 561-569, (1961) 46. Lowman, F. Go, "Radionuclides in Plankton near the Marshall Islands, 1956," UWFL- 54, 31 pp (1958) 47. Lowman, F Go, Palumbo, R F„, and South, D, J., "The Occurrence and Distribution of Radioactive Non-Fission Products in Plants and Animals of the Pacific Proving Ground," UWFL-51, 61 pp» (1957) **8. Marquez, L., da Costa, N. L„ , and de Almeida, I„ G , "Cobalt from Thermonuclear Tests in the Atmosphere," NP-7022, 10 pp. (1958) 19, Marquez, Lo, da Costa, N L , and de Almeida, I G , "Radioisotopes from Fusion in Rain Water: Co 57 , Mn 54 , and Co 60 ," A/Confo 15/ P/2285, 7 pp. (1958) AI-31 0, McConnon, D , "Dose Rate Measurements of Beaches and Islands on the Columbia River between Ringold and Richland," HW-72229 Trb., 21 pp. (1962) 1 Murakami, T , et al , "Inorganic Constituents in Marine Organisms, III, Quantitative Determination of Molybdenum, Lead and Cobalt in Shellfish," Himeji Kogyo Daigaku Kenkyu Hokoku , 13 , pp 98-108 (1961) 65 2. Murthy, G. K , Goldwin, A S,, and Campbell, J. E,, "Zinc ' in Foods," Science , 130 , pp 1255-1256 (1959) 3. Nagasawa, K , et al , "Radioactivity Contamination of Foods by Atomic or Hydrogen Bomb Explosion, IX, Radiochemical Analysis of Radioactive Elements Contaminating Fish Livers in 1958," Eisei Shikenjo Hokoku , 77 , pp. 458-465 (1959) 4„ Nielsen, J. M. , "Behavior of Radionuclides in the Columbia River," TID-7664, pp. 91-105 (1963) 5. Obukhova, Z„ D , et al« , "Content of Manganese, Iodine, Copper, and Cobalt in Cereal Grain and Grass Fodder of Chuya Valley," Mikroelementy v Zhivotnovodstve i Rastenievodstve, Akad. Nauk Kirg. SSR 1962 , 1, pp 71-106 (1962) ~ ! ' ~ 6o O'Connor, J. T„, Renn, C„ E., "Soluble-Adsorbed Zinc Equilibrium in Natural Waters," Journal American Water Works Association , 56, pp, 1055- 1061 (1964) 7» O'Connor, J T , Renn, C, E,, and Wintner, I„, "Zinc Concentrations in Rivers of the Chesapeake Bay Region," Journal American Water Works Association , 56 , pp. 280-286 (1964) 65 ! 8 Osterberg, C, "Zn Content of Salps and Euphausiids," Limnology and Oceanography , 7^ pp. 478-479 (1962) 3. Osterberg, C, Kulm, L D , and Byrne, J„ V„, "Gamma Emitters in Marine Sediments near the Columbia River," Science , 139 , pp, 916-917 (1963) '3, Osterberg, C„, Pattulo, J., and Pearcy, W„, "Zinc-65 in Euphausiids as Related to Columbia River Water off the Oregon Coast," Limnology and Oceanograph y, 9_, pp. 249-257 (1964) U Palmer, R, F„, "Accumulation of Radioisotopes by Rats Chronically Exposed to Reactor Effluent Water," HW-53362, 16 pp (1958) Parker, P. L„, "Zinc in a Texas Bay," Pubic Inst, of Marine Science , 8, pp. 75-79 (1962) Parker, R. A. , and Hazelwood, D„ H., "Some Possible Effects of Trace Elements on Fresh-Water Microcrustacean Populations," Limnology and I Oceanography . £, pp. 344-347 (1962) I c c •• Perkins, R„ W„, and Nielsen, J. M., "Zinc ' in Foods and People," i Science. 129, pp, 94-95 (1959) A I -37 65o Perkins, R. W„, Nielsen, J, M., Roesch, W. Co, and McCall, R. C,, "Zinc 65 and Chromium-51 in Foods and People," Science , 132 , pp. 1895-1897 (1960) 66 <, Report of the Government Chemist upon the work of his Department for the year ending 31 March, 1957, H, M, Stationary Office, London, 36 pp. (1957) 67, Rice, T. R, , "The Role of Phytoplankton in the Cycling of Radionuclides in the Marine Environment," Radioecology , pp. 179-187 (1961) 68, Rice, T, R,, "Review of Zinc in Ecology," Radioecology , pp. 619-633 (1961) 69, Roesch, W, C, McCall, R„ C, and Palmer, H. E., "Hanford Whole Body Counter-1959 Activities," HW-67045, 50 pp, (1960) 70, Rona, E,, Hood, D, W,, Muse, L., and Buglio, B , "Activation Analysis of Manganese and Zinc in Sea Water," Limnology and Oceanography , 7, pp. 201- 206 (1962) 71, Sameshima, M,, and Saito, K., "Radiological Contamination of Fish, Sea Water and Plankton in the Southern Region of Kaigoshima Prefecture during the period from November 1959 to December 1960," Kaigoshima Daigaku Suisan Gakubu Kiyo , 10 , pp, 15-22 (1961) 72, Seymour, A. H,, "Radioactivity of Marine Organisms from Guam, Palau, and the Gulf of Siam, 1958-1959," Radioecology , pp. 151-158 (1961) 73, Skauen, D, M, , "Radioactive Zinc-65 in Marine Organisms in Fisher's Island Sound and its Estuaries. Final Report, December 1, 1959 through November 30, 1963," TID-19922, 50 pp. (1964) 74, Skauen, D, M., "Radioactive Zinc-65 in Marine Organisms in Fisher's Island Sound and its Estuaries: Progress Report," TID- 13509, 32 pp, (1961) 75, Sprague, J. B,, and Carson, W, V,, "Chemical Conditions in the Northwest Miramichi River during 1963," Fisheries Research Board of Canada, Bio- logical Station, St, Andrews, New Brunswick, Canada, 62 pp, (196*+) 76, Swanberg, Jr., F,, "Quantitative Measurements of Some Gamma-Ray Emitting Radionuclides in Nuclear Industrial Workers by Whole Body Counting Techniques," Health Physics , 8_, pp. 67-71 (1962) 77, Thomas, C. W„, Reid, D. L., and Lust, L, F., "Radiochemical Analysis of Marine Biological Samples Following the 'Redwing' Shot Series — 1956," HW-58674, 81 pp. (1958) 78, Thompson, T. G., and Laevastu, T., "Determination and Occurrence of Cobalt in Sea-Water," Journal of Marine Research , 18 , pp. 189-192 (1960) 7 9« Uzumasa, Y,, and Akaiwa, H., "Chemical Investigations of Hot Springs of Narugo, Miyagi Prefecture," Nippon Kayaku Zasshi , 81 , pp, 912-915 (1960) 80, Van Dilla, M. A., "Radioactivity in Nevada Cattle: 1959," LAMS- 2627, pp. 226-233 (1961) AI-33 81. Van Dilla, M. A., "Zinc-65 and Zirconium-95 in Food," Science , 131 t pp. 659-660 (1960) 82. Van Dilla, M. A., and Engelke, M. Jo, "Zinc-65 in Cyclotron Workers," Science , 131 , pp. 830-832 (1960) 83. Vekilova, F. I., et al., "The Abundance of Cobalt in Natural Waters," Izv. Akad. Navk. Azerb. SSR, Ser. Geol-Geogr . -Nauk i Nefti 1962 , 2, pp. 43-52 (1962) " 8f, Vinogradova, Z. A,, and Kovaljskii, V, V,, "Element Composition of the Black Sea Plankton," Dokl. Akad. Nauk SSSR , 147 , pp, 1458-1460 (1962) 85. Warren, H. V., Delavault, R. E., and Irish, R. I., Bulletin Geological Society of America , 62 , pp. 609-618 (1951) 86. Watson, D G«, and Davis, Jo J., "Concentration of Radioisotopes in Columbia River Whitefish in the Vicinity of the Hanford Atomic Products Operation," HW-48523, 136 pp. (1957) 87. Watson, D. G., Davis, J. J,, and Hanson, W, C, "Interspecies Differences in Accumulation of Gamma Emitters by Marine Organisms near the Columbia River Mouth," Limnology and Oceanography , 8_, pp. 305-309 (1963) 88, Watson, D. G., Davis, J. J., and Hanson, W, C, "Zinc-65 in Marine Organisms along the Oregon and Washington Coasts," Science , 133 , pp. 1826- 1828 (1961) 89, Weiss, H. V., and Reed, J, A., "The Determination of Cobalt in Seawater," USNRDL-TR-401, 9 pp. (1960). Journal of Marine Research , 18 , pp. 185- 188 (1960) 90, Weiss, H. V., and Skipman, W. H., "Biological Concentration by Killer Clams of Cobalt-60 and Radioactive Fallout," Science , 125 , p. 695 (1957) 91. Welander, A. D,, "Radiobiological Studies of the Fish Collected at Rongelap and Ailinginae Atolls, July 1957," UWFL- 55, 29 pp. (1958) 92, Young, R. S., "Copper, Nickel and Cobalt Content of Oyster Shells," Journal of Agriculture and Food Chemistry , 8, pp. 485-486 (1960) AI-3 ADDITIONAL REFERENCES FOR APPENDIX fin 1. 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