I
R. C. PALANGE, G. G. ROBECK, and C. HENDERSON Rob& A. Tafi M i t o r y Engineering Center, U. S. Public Health Service, Cincinnati, Ohio ~
Kadloactivity in Stream Pollution
terialp, the increasing peacetime u m for atomic energy products, and the projected dewbpment of atomic power facilities are intmducing new problems in the field of environmental mitation. One of these problems, of direct concern to many state and local health depart-
vate agenaes, ir the possibility of contaminating surface s w a t u s by radioactive wastea and materials. I t is mid that the largest volume of wastes h m the atomic energy indvtty is low in radioactivity and toxicity (7). Thae low-led wastes originate from
age from laboratories, wasw fmm laundering oi garments worn by laboratory and production area personnel, and reactor-woling watem which have been atored and m o n i t o d prior to discharge. High-level wastes, constituting a minor portion of the total wasten discharged,
% - . .. .
I .
Figure 1.
Regional map VOL 48, No. 10
0
-
1w
1847
PLINKTON
lL4MENTOUS 4LGA.L
CAOOISFLY L4RV4E
eIOLOGlCAL
Figure 2.
GROUPS A N D
AND LIMPET
CR4YFISH
JUVENILE FISH SHINERS
SAMPLING R A N G E S
Gross beta activity densities for water, plankton, algae, bottom animals, and fish
are generally concentrated by means such as evaporation, ion exchange, and co-precipitation. Concentrates are usually stored in underground tanks, with or without facilities for cooling. Others are enmeshed in concrete and disposed of by dumping into the ocean at designated locations or by burial in grounds established for such purposes. Although care is taken in monitoring and discharging the low-level wastes, control agencies are faced with the problem of evaluating the pollutional, toxicological, and other hazards involved, as with any other industrial waste discharge. Where such discharge is to surface streams, it is important to know methods by which the situation may be studied, have information needed for evaluating the problem in terms of overall stream pollution control and the effects that may be expected on water use. These studies conducted by the Public Health Service on the Columbia River and its tributaries, where reactor-cooling waters were being discharged, extended from the spring of 1951 to the spring of 1953. One of their principal objectives was to determine the effects of radioactive materials on the physical, chemical, and biological characteristics of these surface waters. Most of the work was confined to the area between Priest Rapids and Paterson, Washington, a section which includes the Hanford Works of the Atomic Energy Commission and McNary Reservoir, an impoundment created in late 1953. Limited studies were made also in Roosevelt Lake, Bonneville Reservoir, and the areas around Portland and Astoria,
1848
NAILS
Ore. (2). The areas studied are shown in Figure 1, The reactor-cooling water was pumped from the Columbia River. Prior to passing through the reactors it was given complete treatment, consisting of coagulation, settling, filtration, and chlorination. After passing through the reactors, the cooling water contained short half-lived radioisotopes formed by the neutron bombardment of dissolved and suspended materials present in the water. Consequently, it was held in open retention tanks for a short period to permit decay of the activity. These effluents were and continue to be monitored routineIy, with the total activity reported as "gross beta activity density." Field and laboratory Procedures The methods of collecting samples for measuring radioactive materials were largely those previously established for collecting samples for other analyses. For the preparation and actual counting, however, new techniques were developed or old ones adapted from other sources. Water. With the relatively great width of the Columbia River and the multiple-point discharge of the pilecooling water effluent, samples were collected from two to five points at each cross section to obtain data on the horizontal mixing in the stream. Samples taken at various depths indicated little or no vertical stratification. Accordingly, routine samples were taken at 4-fOOt depths. Collections were made once a week a t all important points. Sample size was determined by the
INDUSTRIAL A N D ENGINEERING CHEMISTRY
anticipated radioactivity and total solids ;n the water. Generally, the activity density in the Columbia River below the Hanford Works area was such that a 500-ml. portion was adequate. In other river locations, 1000-ml. portions were required for reliable results. All water samples were prepared for radioactivity counting by evaporating them to dryness in such a manner that the final moisture-free residue would be evenly plated on a 1-inch stainless steel dish. Aquatic Organisms. Aquatic organisms on which radioactivity determinations were made included plankton, filamentous algae, bottom animals, juvenile fish, and adult fish. Specimens of each of these were obtained biweekly or monthly at all ranges. Plankton samples were collected by towing a standard, No. 20, silk boltingcloth net across a range for approximately 15 minutes. The concentrate was filtered, and the residue was plated evenly on a stainless steel dish, dried, and counted. Normally, 0.2- to 0.5gram wet weight was needed for an adequate supply. Field collections of algae were made by scraping specimens from rocks, logs, and other objects in the streams and identified, usually as to genera. Duplicate portions weighing about 2 grams were prepared for radioactivity counting by washing free of sand and debris. blotting free of moisture, weighing, digesting in nitric acid, ashing, and spreading the residue evenly on a stainless steel dish. Samples of bottom animals, collected by handpicking from rocks, logs, and vegetation, were separated from debris, sorted into groups, and identified as to
order. Duplicate portions of each group, weighing between 1 and 2 grams per portion, were prepared for counting by blotting, digesting, ashing, and plating. Collections of juvenile fish, usually taken with seines and nets, were sorted according to species, identified, and arranged in size groups for radioactivity determinations. Three portions, containing one or more fish from each size group of each species, were used whenever possible. Each portion was usually made u p of one to six whole individuals of the same species. Portions weighing about 2 grams were generally used-a single fish was prepared when the individual weight was between 2 and 10 grams. Fish weighing over 10 grams were considered as adults for radioactivity counting purposes. Each individual specimen within a sample was measured, blotted free of moisture, and placed in a tared 50-ml. beaker. The sample was then weighed and prepared for counting by digesting and evaporating, according to the procedure used for bottom animals. For adult fish, radioactivity determinations were confined to certain parts and organs. Where available, three individuals of a species were used from each collection. After identification and measurement of total length and weight of each fish, 1- to 5-gram samples of scales, muscle, liver, bone, ovaries or testes, kidney, stomach contents, or skin were placed in tared 50-ml. beakers and weighed. As was the case with juvenile fish, the samples were prepared for counting by the same procedure used for bottom animals. Mud sampling was limited because there was very little such material in this swift, rocky-bottomed stream. Mud could be found in a few backwater areas, particularly in tributaries, but in nearly all cases, samples were limited to the near-shore areas. Samples of mud were collected in wide-mouthed jars by scooping up soil where the river was 1 to 2 feet deep, in sufficient quantity to result in a t least 20 grams of dry sample. After draining off excess water, a representative portion of the soil was oven dried, weighed, digested with nitric acid and heat, plated on a 1-inch stainless steel dish, ashed, and reweighed before counting. Radiochemical Analyses. I n an effort to identify the various radioisotopes present in water and aquatic organisms, radiochemical analyses were made on samples of Columbia River water, plankton, filamentous algae, caddis fly larvae, and fish. Samples were collected in the manner previously discussed but it was necessary to obtain larger amounts, usually 4 to 5 liters of water and up to 10 grams of organisms. The radiochemical work involved a separation into soluble and insoluble portions with a further breakdown into elements or
groups of elements, using the chemical carrier technique. Counting Methods. T o obtain a measure of the radioactivity, several factors had to be resolved or determined. These included selection of counting instruments and appurtenances; determination of various correction factors, such as geometry, air and mica-window absorption, and self-absorption; development of decay curves; and identification of beta emitters ( 2 ) . Only limited counting for emitters of alpha particles and gamma rays was done, because it was known that little or no material creating this type of activity was entering the stream. Two types of counters were considered and tried for the routine beta activity density determinations-the proportional or internal flow counter and the endwindow Geiger-Muller tube counter. O n the basis of the large sample load, the levels and type of activity encountered, and other factors, the endwindow G-M counter was selected for general use. For routine water and biological samples, a counting time of not less than five minutes nor longer than 15 minutes was normally adequate. Correction factors, needing measuring and repeated checking, had to be applied to the counting rate to obtain absolute values of radioactivity. Findings and Discussion The survey included determination of the hydrological, physical, chemical, biological, and bacteriological characteristics of the river. Unless otherwise stated, the conditions discussed here were found in the Priest Rapids to Paterson section. Findings. Stream discharges followed a seasonal pattern, with high flows of about 300,000 to 500,000 cubic ft./second occurring between May and July, and flows under 100,000 cubic ft./second occurring during the remainder of the year. Tributary flows also followed a seasonal pattern, but with peak runoffs occurring about a month earlier. The water in the Columbia River was quite clear, with average turbidity values of less than 7 p.p.m. except during high flow periods. Tributaries were somewhat more turbid and had some effect on the main river. Water temperatures varied by seasons from a low of 2' C. in February and March to a high of about 20' C. in the late summer and early fall. Tributary temperatures were slightly higher, with maximum values reaching 24' C. Dissolved oxygen concentrations the year round were at or near saturation. Slightly lower concentrations were found in the tributaries, especially during lowflow periods. The pH values varied from 7.6 to 8.2,
and alkalinity values from about 50 to 100 p.p.m. Corresponding values for the tributaries were somewhat higher. Mineral analyses showed concentrations of the principal elements to be generally lower than would be of importance from the pollutional or toxicity standpoints. The coliform MPN index (most probable number) within the Priest Rapids to Paterson section varied from under 3.6 to 4500 per 100 ml. The higher values were found below the populated areas and the tributaries. Since the completion of these studies, sewage treatment plants have been placed in operation a t all municipalities. Generally speaking, the physical and chemical conditions in both the main river and the tributaries were well within limits favorable to the support of a good, mixed, aquatic biota. Plankton in the Columbia River were principally phytoplankton, with diatoms making up over 90% of the population. The principal genera present were Asterionella sp. Cyclotella sp. Fragilaria sp. and Synedra sp. Asterionella and Cyclotella occurred in definite pulses; Asterionella was predominant in the spring months and Cyclotella in the later summer and fall months. The tributaries were responsible for the pulses of Cyclotella. Bottom animals consisted primarily of clean water forms, such as may fly nymphs, midge fly and caddis fly larvae, and mollusks. Average numbers and weights showed very little variation between ranges. The river was average to rich in fish food organisms. The tributaries contained similar organisms, but somewhat larger numbers and weights, with average values about twice those in the main river. Fish populations consisted of both coldand warm-water species. The major game and food fish were migratory species (such as chinook salmon, blueback salmon, and steelhead trout) and resident species (such as black bass, sturgeon, and whitefish). Other species, mostly rough and forage fish (such as suckers, carp, shiners, and dace) were quite abundant. The maximum and average gross beta activity densities for various types of samples taken just below the reactors were :
Samble, Type Water Plankton Filamentous algae Caddis fly larvae Juvenile fish (shiners) Adult fish (suckers) Bone Muscle a pc./ml. VOL. 48, NO. 10
Beta Activity Densities, X 70-6 p c . / G . M a x i - Average mum gross 19. 6" 80,000 13,000 10,000
20,000 6,000 7,000
9,000
1,300
5,000 1,100
1,200 300
OCTOBER 1956
1849
The highest gross beta activity density values for water and various aquatic organisms were found just below the reactor discharges. There was a fairly sharp decrease for about 25 miles and a constant but less sharp decrease thereafter. In the next 60 miles or so, values decreased to about one tenth of those found just below the reactors. A measurable amount, somewhat higher than background, persisted to the mouth of the river at Astoria, Ore., over 350 river miles below the reactors. Average background values were at or below 1 X 10-6 microcuries per gram for aquatic organisms, and 1 X 10-8 pc, per ml. for water. Radiochemical analyses showed that the principal radioisotopes consisted of short half-lived beta particle emitters, such as Cue*, Mn56, NaZ4, As76, Si31,and P32. Some of the radioisotopes in water were being absorbed or concentrated in aquatic organisms. The total activity in the organisms was found to be several times that in the water, while an individual isotope could be concentrated to an even greater extent. The principal radioisotope concentrated in aquatic organisms was found to be P32. This was responsible for 90y0 or more of the activity in river fish, but less than 2y0of the activity in the water. Materials of shorter half-life. such as NaZ4, Cu64, Mn56, Si31, and As’6, were the principal products concentrated by plankton. Discussion. The accumulation of radioactive materials by aquatic organisms followed a definite pattern (Figure 2). Plankton (mostly phytoplankton) and filamentous or attached algae, which absorb nutrients directly from the water, showed the greatest activity per unit of weight. Next were bottom animals which feed on this material, and then juvenile fish which feed on these animals. At the end of the chain were the adult fish which feed on juveniles. Exceptions to this general pattern were some of the fish which may shorten the chain by feeding directly on plankton, filamentous algae, or bottom animals. The variations of activity in the Columbia River water were due primarily to changes in quality and quantity of cooling water discharges, dilution during seasonal high river flows, and normal decay of the isotopes present. Radioactivity in plankton and attached algae were directly dependent on levels in the river water. Activity in aquatic animals was dependent upon metabolic rates which, in turn, depend upon water temperature and activity of the material upon which the animals feed. The maximum activity density occurred during low water stages and high water temperatures, usually in the late summer and fall. Migratory fish such as salmon, the
1 850
adults of which do not feed while in fresh waters, had very low activity at the same time that levels in actively feeding species, such as suckers, bass, and whitefish, were high. Radioactive materials were concentrated in all parts of the body of the fish. Activity, however, was about ten times higher in scales, bone, and internal organs than in the edible parts such as the muscle or skin. As far as could be determined, there were no measurable changes in the physical, chemical, or bacteriological characteristics of this river as a result of the discharge of reactor cooling waters over a period of several years. No deleterious effects on aquatic populations, resulting from the levels of activity found during this survey, could be detected. I t was found that river organisms were concentrating specific isotopes, such as P32, to levels many times those found in water. However, the fact that some of these organisms, such as fish, may be utilized to a large degree by humans, is of potential public health significance. There was no evidence of build-up or carry-over of radioactive materials from year to year. The specific radioisotopes present are the major consideration in a survey of this kind. Maximum permissible levels may be much higher for the shorter half-lived isotopes such as P3*, than for long half-lived materials such as Srm. Radioactivity density levels of the order of magnitude found in the Columbia River water and aquatic organisms would be of utmost importance if derived from long half-lived isotopes. The presence of only short half-lived isotopes in the stream greatly reduced the potential hazard. Summary The pollution of streams by radioactive materials has been and continues to be of concern to state and local health authorities. While methods of sampling for radioactive contaminants are in many ways similar to those used in conventional surveys, some new concepts must be considered. The organic loads and consequent sampling for biochemical oxygen demand, dissolved oxygen, and coliforms which have been the major interest of many pollution surveys, are not of great significance here. The specialized apparatus and techniques for obtaining such samples may not be necessary. Determination of the identity and quantity of radioactive materials requires new approaches, which are rapidly being developed. Conventional chemical analyses routinely made in most pollutional surveys may need to be re-evaluated. Emphasis on determination of such components as color, odor, alkalinity. ammonia, chlorides, and sul-
INDUSTRIAL A N D ENGINEERING CHEMISTRY
fates may need to be replaced by thosc for metal ions or other toxic components. The location of sampling stations, the techniques in collection, and the volume of samples must be based on the amounts and characteristics of the radioisotopes present. Major considerations from the standpoint of aquatic life are changes in water temperatures, chemical toxicity. and the accumulation of radioisotopes in aquatic organisms which may either have an effect on the organisms thrniselves, or their use as human food. Administrative agencies should bc acquiring the proper staff and knowledge to deal with radioactive waste discharges as they now deal with other industrial waste effluents. -4ssistance may be obtained from various federal agencies, including the Atomic Energy Coinmission and Public Health Service. ‘The ultimate goal, however, should be the integration of these staff functions into the over-all local organization. Pollution abatement agencies should initiate surveys to determine the background radioactivity levels in their local streams. This will provide a basis for determining the degree of radioactive contamination caused by future nuclear energy installations, as well as the levels due to natural causes. Such a program would also provide opportunity for training and development of the staff and resources required to deal with lhis type of problem. Present indications are that the bulk of the wastes from nuclear installations will continue to be of low levels, and that such wastes will constitute the principal discharge to streams. Waterquality studies on the Columbia River, where such wastes are discharged, disclosed no observable effects on the chemical, physical, and biological characteristics of the stream over a p w i d or several years.
Acknowledgment These studies weir: carried out in cooperation with the U. S. Atomic Energy Commission, General Elect] ic Co., and the States of Oregon and Washington. Their assistance is qratrfully acknowlrdged.
Literature Cited (1) Lieberman, .J. A , , Gorman, A. E., Proc. Am. Soc. Civil Cngrs. 80, Separate No. 422 (March 1954). ( 2 ) Robeck: G. G., Henderson, C.: Palangr, R. CI., “Water Quality Studies on the Columbia River,” C . S. Public
Health Service, Sanitary Eiigi.inrei-ing Center, Cincinnati 26, Ohio, 1954.
RECEIVED for review September 6, 1955 ACCEPTRD April 71,1956
