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The objectives of this research were (1) to analyze the transfers of 137Cs and 60Co in a retention pond, with emphasis on aquatic insects and (2) to determine if detectable concentrations of these radionuclides are exported by emerging aquatic insects. We analyzed the radionuclide concentrations in the following components: water solution, bottom sediments, suspended particulate matter, plankton, floating mats of filamentous algae, benthic macroinvertebrates, and emerging aquatic insects. Samples were collected quarterly from June 1981 to April 1982. The lowest concentrations (in picocuries per milliliter) occurred in solution (range: 1.4 X 10(2) to 3.2 X 10(2) for 137Cs and 8.1 X 10(-1) to 2.2 X 10(0) for 60Co). The highest concentrations (in picocuries per gram dry weight) occurred in the sediments (range: 1.5 X 10(4) to 1.1 X 10(8) for 137Cs and 1.0 X 10(2) to 4.3 X 10(6) for 60Co). The primary producers and aquatic insect consumers had concentrations of both radionuclides that were two to four orders of magnitude higher than the respective concentrations dissolved in water but two to three orders of magnitude lower than the concentrations in the sediments. The concentrations of both radionuclides decreased successively at higher trophic levels. There were considerable temporal variations as the radionuclides cycled among the abiotic and biotic components of the pond. Emerging adult aquatic insects had lower concentrations of both radionuclides than the immature stages that lived in the pond (adult/immature ratio about 0.25). Because the emerging adult insects contain detectable concentrations of radionuclides, have relatively long life spans, and disperse away from the aquatic habitat, we conclude that adult aquatic insects would be effective biological monitors.

In 1978 negotiations were Initiated between the city*of Oak Ridge ana the Department of Energy (DOE) Oak Ridge Operations Office to consider the land disposal of treated sludge from a new city sewage treatment plant, which was scheduled for completion In 1983. The sludge was to be placed on several parcels of land (~ 1500 acres) located within the DOE Oak Ridge Reservation for a trial period of five years. The sludge was to be used as a nitrogen and phosphorus nutrient supplement for tree planting operations on poor quality forest sites within trie Reservation. The initial sludge disposal site consisted of 65 acres located on the southeast side of Chestnut Ridge, bordered on the south by the old Bethel Valley Road and on the west by Mount Vernon Road. Deposition on this site was begun in November 1983. On March 22, 1984, It was learned that some of the deposited sludge had been contaminated with various radionuclides primarily Co-60 and Cs-'.37. A radiation survey had been performed above the City's sewage main on Emory Valley Road. The readings were as high as 45 uR/hr (5 times background) midway between the L&N railroad line and Lafayettt Drive. Disposal of sludge on the 65-acre site was temporarily halted on March 25, 1984 and the comprehensive sampling and monitoring study described in this report was instituted on March 30, 1984. A systematic random sampling design was used to characterize the entire disposal site ("65 acres). Eleven transects were run perpendicular to the surface flow gradient, 140 ft. apart. Soil cores were collected on March 31 and April 1, 1984 along each transect 180 ft. apart for a total of 117 cores, which were extracted to various depths, depending on the ability to penetrate the soil layer. Each core was separated into three parts: the upper 3 inches, the middle section, and the bottom 3 inches. The upper portion was considered most likely to represent the previously broadcast sludge; the midd'e portion, the tilled soil mixed with sludge; and the bottom portion, the unoisturbed subsurface layer. Sufficient core material was taken iii IV at each coring site to ensure the collection of enough material for analytical precision. Samples were analyzed for gamma activity, principally from Cs-137 &nd Co-60, in all top and middle layer samples. Where detected, Mn-54 and Cs-134 were also reported. Alpha and Beta activity analyses, which are time-consuming, and lauor-intensive, were performed on a random sampling of the extracted cores consisting of 25% of the top portions of the cores (30 sampler). Samples were analyzed for Sr-90, U-234, U-235, U-238, Pu-238, and Pu-239. The majority of the radioactivity was determined to be in the upper 3 inches of soil. A statistical treatment of the analytical results provided an estimate of the total activity at the site, the vertical distribution of the gamma activity, and the areal distribution of the primary radionuclides. A total of 170 mCi of activity was estimated as present in the top 3-inch layer of the 65-acre site, 69% of which was contributed ...

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