[en] The Peach Bottom Atomic Power Station (PBAPS) has contributed measurable quantities of radioactivity to Conowingo Reservoir, an impoundment of the lower Susquehanna River. As a part of an ongoing radiological assessment program, concentrations of plant-related radionuclides in sediments have been monitored in spring and fall since 1980. Mass balance estimates derived from grab samples of surface sediments (< 10 cm) indicate that less than 20% of reactor released ⁶⁰Co, ⁶⁵Zn, ¹³⁴Cs and ¹³⁷Cs is present in these sediments. Significant seasonal variations in radionuclide trapping efficiency by the reservoir are not apparent. Deep core samples (c.200 cm) confirm that some, but not all, of this surface sediment radionuclide inventory remains within the reservoir - trapped in discrete locations by subsequent sediment accumulation. The remaining radionuclide mass, in dissolved or particle-associated form, appears to be transported downstream, through Conowingo Dam, to upper Chesapeake Bay. The detection of PBAPS-derived radionuclides in the sediments of upper Chesapeake Bay, primarily the Susquehanna Flats, confirms the transport of these radionuclides from the lower Susquehanna River. (author)

[en] Radionuclide levels were measured in tissues, gut contents, diet items, and water at site of capture, of adult beavers from the Serpent River drainage basin which contains U tailings at Elliot Lake, Ontario, and from nearby control sites. Levels of ²²⁶Ra in beaver bone, muscle and kidney were highest in animals from locations close to U tailing; liver levels did not vary by site. Environmental ²²⁶Ra levels were within ranges previously reported at these or similar locations elsewhere; levels in beaver gut contents reflected levels in diet items. Concentration ratios exceeded unity only between some vegetation items and beaver bone at the Elliot Lake site and were less than 0.19 between vegetation and other tissues. In two beavers with tissue levels of ²²⁶Ra higher than others sampled, neither ²³²Th nor ²³⁰Th were detected in bone, muscle or liver tissues. U-238 was measurable in bone, muscle and liver; ²²⁸Th in bone, ²¹⁰Po bone, muscle and liver; and ²¹⁰Pb was measurable only in bone. Estimated yearly intakes of radionuclides by people eating beavers were calculated to be below current allowable levels set by the Canadian regulatory authorities. (author)

[en] This paper presents the results of various decontamination experiments aimed at evaluating ⁶⁰Co retention by Scenedesmus obliquus, and the respective role played by absorption and adsorption in the contamination of the alga by this radionuclide. The physiological condition of cells is not involved in radiocobalt desorption, which seems to indicate that the phenomenon is of a passive nature. When the precontamination time is extended, the proportion of adsorbed ⁶⁰Co decreases, and the final percentage of radionuclide retained increases. These results are confirmed by bringing cells into contact with a strong chelating agent. The elimination of ⁶⁰Co in the presence of EDTA undergoes a sharp decrease which is correlated with the increase in the duration of the precontamination phase. The use of a weaker complexing agent, such as NaCl, leads to the hypothesis of there being 2 types of ⁶⁰Co receptor on cell membranes. (author)

[en] This paper reports the results of several experiments carried out to evaluate uptake and retention by a limicolous midge larva of ⁶⁰Co retained in sediment, either adsorbed on mineral particles or bound to planktonic algae. In order to determine their relative contributions in radionuclide accumulation, the different vectors (water, algae and sediment) were first labelled individually and then simultaneously. ⁶⁰Co accumulation from water and from algae results in a maximum concentration factor of 30 and in a mean trophic transfer factor of 4.5 x 10^-3. The level of contamination of midge larvae from sediment is markedly influenced by the presence of endogenous organic matter. Thus the radionuclide transfer factor is about twice as high for larvae placed in labelled raw sediment than for larvae placed in labelled incinerated sediment, in the presence as in the absence of contaminated planktonic algae. Irrespective of the contamination conditions, ⁶⁰Co depuration from midge larvae is a very rapid phenomenon that corresponds, in all cases, to a radionuclide half-life of only a few days. (author)

[en] The uptake by swards of three activation products (⁵⁴Mn, ⁵⁷Co and ⁶³Ni) was studied in a long-term field experiment. Some of the soils used in the investigation were sampled in the vicinity of four Swedish nuclear power plants, while the others represented the most frequent types of agricultural soils occurring in Sweden. Data on the uptake by clover and timothy during a 9-year period were used for the calculation of soil-plant transfer factors of these nuclides. The temporal distribution of the transfer factors and the variations exhibited by the different nuclides were examined, as well as the differences between crops. The increased uptake at the early stage of the experiments (first year effect) observed in clover is discussed. Regression analyses employed to quantify the dependence of uptake on soil parameters showed that the soil characteristics that most influenced the uptake are the pH and the soil contents of calcium and potassium. (author)

[en] A selection of wild animals was sampled in the winter of 1986/87. The sites chosen for sampling were based on information obtained from surveys carried out by The Institute of Terrestrial Ecology in the spring and autumn of 1986. Animals included deer, grouse, hares and rabbits, and foxes which were collected as a top carnivore in the food chain. Variation in concentration of caesium between species from the same area was unpredictable; rabbits never exceeded 200 Bq kg^-1 (fresh wt) of ¹³⁷Cs in their flesh, even when adjacent to deer forests with over 1000 Bq kg^-1 in the venison. The greatest complication arose from areas of peaty uplands where the pre-Chernobyl ¹³⁷Cs from weapons-testing was much higher than expected. This pre-Chernobyl contribution amounted to 630 Bq kg^-1 in a red grouse from the Pennines, and 650 Bq kg^-1 in a roe deer from near the Borders, being c. 60% of the total. Significant differences in concentration factors were found depending on species, food, sex, breeding condition and age. Contrasting the decrease of the two caesium isotopes in roe deer from forestry on peat with those from woodlands on mineral soils, it appeared that after an initial fall in concentration, the only decrease thereafter occurred on the mineral soils. Nowhere were radiocaesium concentrations high enough to cause concern amongst consumers of game and other wild animals, even when levels exceed 3000 Bq kg^-1 (fresh wt) as they did in red deer, red grouse and the blue hare. (author)

[en] Since 1983 concern has been expressed about the apparent decline in numbers of birds in the Ravenglass estuary in west Cumbria, particularly of the black-headed gull colony on the Drigg dunes, and suggestions have been made that this decline might be due to excessive radiation in the birds' food and their general environment. Twelve species of marine invertebrates from Ravenglass, known to be important foods for birds, were analysed, and further samples were taken from sites along the west Cumbrian coast. None of these samples showed excessive contamination with any of the radionuclides analysed. Analysis of a sample of bird carcasses from the area showed oystercatchers (Haematopus ostralegus) and shelduck (Tadorna tadorna) to have some of the highest concentrations of ¹³⁷Cs in their tissues; yet their breeding success and populations were not affected. Black-headed gulls were found to be feeding mainly inland, and were the least contaminated with radionuclides of all the birds at Ravenglass, yet this species and its breeding success were in decline. Calculations of the total dose equivalent rate to the whole body of the most contaminated black-headed gull amounted to 9.8 x 10^-4 mSv h^-1 (∼ 8.4 x 10^-4 mGy h^-1, whole-body absorbed dose rate), and the background exposure dose was of the order of 8.3 x 10^-4 mGy h^-1. As a minimum chronic dose of 1000 mGy day^-1 has been found necessary to retard growth of nestling birds, and 9600 mGy over 20 days of incubation to cause the death of 50% of embryos in black-headed gulls' eggs, the concentrations of radionuclides in the foods, body tissues and general environment were at least three orders of magnitude too low to have had any effects. (author)

[en] The activity concentrations of radionuclides (⁶⁰Co, ⁵⁴Mn, ¹³⁷Cs, ⁴⁰K) in whole plants of Fucus vesiculosus of different ages, and also in tissues of different ages from the same plant were investigated in the vicinity of the Barseback nuclear power plant in southern Sweden. Activity concentration differed between the tissues of different age of the plants, depending on the radionuclide as well as the time of year. The highest concentrations of ⁶⁰Co and ⁵⁴Mn were measured in the older parts of the plants in spring and summer, while the activity concentrations of ¹³⁷Cs and ⁴⁰K were highest in receptacles and new vegetative fronds. The discharge of radionuclides from the nuclear power plants was reflected in the measured activity concentration in the algae. For ⁶⁰Co, the response seemed to be smoothed out when considering the whole plant, while the new vegetative tissue better reflected the discharge during the autumn. Thus it is important to have knowledge about the autecology of the organism when it is used as an indicator for radionuclides. (author)

[en] Biological half-lives for various radionuclides have been determined for many animals kept in the laboratory or under controlled conditions. Following the fallout from the Chernobyl accident and its subsequent ingestion by wildlife, no one knew how long it would take for the wild animals to eliminate the radionuclides, and in particular radiocaesium, from their bodies. In this study of roe dee (Capreolus capreolus), bucks (males) were shot at weekly/fortnightly intervals from mid-May till the end of July, as part of the annual cull on an area, which included some young forestry (Stone Chest - National Grid Reference NY480790), planted in 1971/72. The ratio of ¹³⁷Cs:¹³⁴Cs, typical of the Chernobyl fallout, was seldom observed in these animals due to the highly variable concentrations of ¹³⁷Cs originating from bomb fallout. Therefore, ¹³⁴Cs was used instead because its presence was almost entirely due to the Chernobyl fallout. After using a log₁₀ transformation of the ¹³⁴Cs concentrations, a significant (p<0.01) regression was obtained which accounted for 85% of the variation. From the regression, the ecological half-life for ¹³⁴Cs was found to be 28.3 days. (author)

[en] Wild rodents were collected alive in a suburban area to the north of Rome before, during, 6 months and 1 year after the Chernobyl accident. Radionuclide determinations to assess their content of ¹³⁷Cs and mutagenicity tests (bone-marrow micronucleus test and sperm abnormalities assay) were performed on the captured animals. The results obtained for the species Mus musculus domesticus (which was the rodent captured in highest numbers), compared with the results obtained before the fallout, showed an increase of both micronucleated polychromatic erythrocytes (MPCEs/1000 PCEs) and ¹³⁷Cs content during and after the fallout. (author)