Biogeochemical effects of uranium and thorium

摘要

The paper describes effects of uranium and thorium bioaccumulation in widespread native plant species couch-grass and plantain. The experiments were performed in a field in 2005-2006. The plants were watered with solutions of uranium, thorium, and a mixture of U and Th. Concentrations of twenty-five elements in the plants and in the rhizosphere soil were determined by instrumental neutron activation analysis. All the plants accumulated rather large amounts of U and Th but the rates of U uptake were higher than those of Th. The treatments affected significantly concentrations of several other elements both in different plant parts and in soil. There were rather significant and regular diurnal changes in concentrations of various elements in different plant parts. The short-term variations were species specific. The treatments with U and Th had significant influence on the chlorophyll contents of the plant leaves. These were decreased, especially after treatment with U. Both Th and especially U affected the total amount of rhizosphere proteins: concentration of the soil proteins increased as compared to that in the control soil.