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

Abstract

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.