Radiocesium fallout

The radiocesium fallout in Sweden was among the highest in Western Europe - exceeding 60,000 Bq/m on Sweden s Baltic coast - and... 

The amount of fallout radioactivity deposited on plant surfaces depends on the exposed surface area, the developmental season of the plants, and the external morphology. Mosses, which have a comparatively large surface area, showed highest concentrations of radiocesium. In northern Sweden, most of the radiocesium fallout was deposited on plant surfaces in the forest ecosystem and was readily incorporated into living systems because of browsing by herbivores and cesium s chemical similarity to potassium. In August 1992, the distribution of Cs fallout from Chernobyl in a Swedish forest was 87% in soils, 6% in the bryophyte layer, and 7% in standing biomass of trees ... 

Caribou in northern Quebec contained up to 1129 Bq 137Cs/kg muscle FW in 1986/87, but only 10 to 15% of this amount originated from Chernobyl the remainder is attributed to fallout from earlier atmospheric nuclear tests (Crete et al. 1990). The maximum concentration of 137Cs in meat of caribou (Rangifer tarandus granti) from the Alaskan Porcupine herd after the Chernobyl accident did not exceed 232 Bq/kg FW, and this is substantially below the recommended level of 2260 Bq 137Cs/kg FW (Allaye-Chan et al. 1990). Radiocesium transfer in an Alaskan lichen-reindeer-wolf (Canis lupus) food chain has been estimated. If reindeer forage contained 100 Bq/kg DW in lichens and 5 Bq/kg DW in vascular plants, the maximum winter concentrations — at an effective half-life of 8.2 years in lichens and 2.0 years in vascular plants — were estimated at 20 Bq/kg FW in reindeer-caribou skeletal muscle and 24 Bq/kg FW in wolf muscle (Holleman et al. 1990). 

The accident at the Chernobyl, Ukraine, nuclear reactor on April 26, 1986, contaminated much of the northern hemisphere, especially Europe, by releasing large amounts of radiocesium-137 and other radionuclides into the environment. In the immediate vicinity of Chernobyl at least 30 people died, more than 115,000 others were evacuated, and the consumption of locally produced milk and other foods was banned because of radiocontamination. The most sensitive local ecosystems were the soil fauna and pine forest communities. Elsewhere, fallout from Chernobyl measurably contaminated freshwater, marine, and terrestrial ecosystems, including flesh and milk of domestic livestock. Reindeer (Rangifer tarandus) calves in Norway showed an increasing frequency of chromosomal aberrations that seemed to correlate with cesium-137 tissue concentrations tissue concentrations, in turn, were related to cesium-137 in lichens, an efficient absorber of airborne particles containing radiocesium and the main food source of reindeer during winter. A pattern similar to that of reindeer was documented in moose (Alces) in Scandinavia. 

Bunzl, K., Schimmack, W., Belli, M., and Riccardi, M., 1997, Sequential extraction of fallout radiocesium from the soil Small scale and large-scale spatial variability. J. Radioanal. Nucl. Ghent. 226 47-53. 

There are various sources of radiocesium in the environment. The input from atmospheric weapons testing in the mid-twentieth century leads to the most widespread and homogeneous contamination of soil and water. The accumulated contribution of Cs in Europe from this source is estimated to be about 1000 Bq m 2. The fairly uniform deposition of Cs from fallout followuig the nuclear weapons testing has led to the widespread use of this isotope as a tracer of erosion (Ritchie and McHenry, 1990 Agudo, 1998). The accident that occurred at the Chernobyl nuclear plant in April 1986 led to more localized contamination. The events that led to this accident and the consequences have been widely... 

Lassey KR. 1979. The transfer of radiostrontium and radiocesium from soil to diet Models consistent with fallout analyses. Health Phys 37 557-573. 

On a mesoscale (100 m) level, no significant accumulation of radiocesium in relation to different slope conditions was found. Small scale (m) hollows, however, contained a higher amount of Chernobyl-derived Cs than. small scale collines, hut there was no. statistically significant differences found for radiocesium from global fallout. It is concluded that the inhomogenous distribution of radiocesium is caused by a run-off phenomenon during the deposition of Chernobyl-derived Cs in May 1986 rather than by sediment redistribution in the last 35 years. The consequences of these results for soil-to-plant radiocesium transfer models based on soil/plant radiocesium concentrations or transfer factors are discussed. 

Chernobyl fallout crosses, Cs derived from the global fallout black triangles, The values for K are fitted best with an exponential model (dashed line), (b) Normalized isotropic variograms and best fitted model for plant variables. Open squares, Cs open triangles, The values for radiocesium are fitted with a spherical model (dashed line), the one for with an exponential model (solid line). 

Between 1988 and 1992, Cs levels declined in sediments from 52 lakes in southern Finland by 27% and in fish tissues by 26-39%. Radiocesium-137 concentrations in whole freshwater fishes from Norwegian lakes contaminated by Chernobyl fallout were quite variable. Major sources of Cs variations included the fish weight and growth rate, and these were related to fish age and diet. Change over time in dissolved phase Cs concentrations of lake water is significantly related to water residence time and mean lake depth these variables have been incorporated into models to predict estimates of Cs decline in freshwater systems. Radiocesium-137 activity in muscle of brown trout (Salmo trutta) and Arctic char (Salvelinus alpinus) from six lakes in Cumbria, England, between June 1986 and October 1988 were highest between December 1986 and March 1987, with maximum values of about 1200 Bq/kg FW in trout and 350 in char. Maximum Cs values were related to the initial concentration of Cs in both water... 

Seawater samples and sea grass Posidonia oceanica were collected along the Spanish Mediterranean coast. The mean activity concentrations for Cs and Cs in surface waters collected fi-om the Spanish Mediterranean shoreline were (4.8 0.2) Bq/m and (0.27 0.01) Bq/m (1987-1991), respectively. Because of its short radioactive decay period, Cs has not been detectable in the Western Mediterranean waters. From 1987 to 1991, the enhancement of radiocesium levels in the Spanish Mediterranean marine environment was observed after the Chernobyl accident. The Cs/ Cs isotopic ratio in Chernobyl fresh deposition was used to identify the weapon-test fallout and Chernobyl deposition components. The mean isotopic ratio Cs/ Cs is 0.057 0.003. The mean Cs/ Cs isotopic ratio of Posidonia oceanica is 0.20 0.04. This value is twice that of the Cs/ Cs ratio (0.11 0.01) observed for water samples from the vicinity of Vandellos NPP. The activity concentration of Cs input into Mediterranean waters as a consequence of the post-Chemobyl deposition is estimated to be (1.16 0.04) Bq/m, which brought about an increase of (33 3)% over the previous levels. Activation and fission products Ru, " Ag, Cs, Cs, and Ce are detected in all samples of Posidonia oceanica. Mean radiocesium levels in the bioindicator were (1.02 0.25) Bq/kg... 

B. Definition of dimensionless moderator (Dim. less) for radiocesium in lakes. Empirical data from 41 Swedish lakes (data from H anson 1991). Cspi = Cs in pike in Bq/kg ww, Cssoil = fallout in Bw/m p//J5=mean lake pH from 36 months. Regression lines for data for 1988 and 1989... 

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