Effects of transuranic (239Pu, 239Np, 241Am) elements on soil fauna

Summary The ecological after-effects of soil pollution by the transuranic elements ²³⁹Pu and ²⁴¹Am were studied in field experiments using soil animals as bio-indicators of radioactive pollution. In a long-term field experiment with ²³⁹Pu in chernozem soils an obvious decrease in soil macrofaunal populations was apparent after 3 years. The population density of earthworms and insect larvae had halved, and that of microarthropods had decreased by a factor of 5.5. After 18 years the major portion of ²³⁹Pu had been transformed to ²⁴¹Am and the population density and species diversity in the polluted plots did not differ from those in the control plots, although there were differences in spatial distribution. In experiments with ²⁴¹Am, the soil pollution effect had decreased 1 year after exposure. The accumulation of ²³⁹Pu, ²³⁹Np, and ²⁴¹Am in earthworm body tissues was studied in laboratory experiments. The maximum concentrations of ²³⁹Pu and ²⁴¹Am in earthworms were recorded after 7 days, and for ²³⁹Np after 3 days. The dynamics of ²³⁹Pu, ²³⁹Np, and ²⁴¹Am accumulation by three earthworm species were studied over 1–65 days and doses of irradiation from the incorporated radionuclides and gut soil radionuclides were determined.