RESUMO
The biochemical characteristics of Duschekiafruticosa, grown for a long time under a variety of exposure doses of natural background radiation (up to 150 µR/h) was studied. Uranium was found to make the dominant contribution to the y-background exposure doses. The pH-values and the content of organic matter in soils within the surveyed territory remained unchanged. Accumulation of radionuclides of uranium and thorium in the "soil-plant" system was studied. It is shown for the D. fruticosa that U and Th uptake decreased with y-background increasing. Study of anti-free radical and anti-peroxide cells' protection system indicated a balanced activity of prooxidant-antioxidant systems in the cells of the D. fruticosa leaves. The combined effect of incorporated uranium and thorium is accompanied by a significant increase in chlorophyll content in D. fruticosa.