Radiocesium forest soil

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. 

Corresponding to the analogy with potassium, a radiocesium cycle has been established in forest ecosystems which prevents radiocesium being lost from the mineral cycles of forest systems (Riesen, 2002). Either no or only very little radiocesium is lost by diffusion into the deeper zones of the soils (Sheppard and Thibault, 1991). [Under the presumption that the pH-value of the soils is low (<5.5) and there is a lack of potassium in the soils, these two conditions are fulfilled for almost all forests in Europe.] Almost all radiocesium cycles in the forest ecosystem function in the same... 

The contamination of the game is species-dependent (see Table 1-5.1), due mainly to the types of plant eaten by the animals, as different plant species absorb different amounts of radiocesium from the soil (Table 1-5.3). Plant species gro ving vithin the same region also exhibit large variation in cesium uptake and accumulation (Table 1-5.4). Examples of this include mushroom species found in the Bavarian Forest and the Cortinarius species, vhich retain high cesium levels (Haffelder, 1995, Steine et ah, 2002). 

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 ... 

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