Influence of Microbial Activity on Technetium Behaviour in Soil Under Waterlogged Condition

Abstract

AbstractThe behaviour of Tc in soil depends upon its chemical forms. Under aerobic conditions, Tc is present as pertechnetate Tc+7(TcO4–), which has a high geochemical mobility and bioavailability. However, the form changes through a combination of factors such as redox conditions and microbial activity in soils. The anaerobic condition can be supplied in waterlogged rice paddy soil, which is common to Japan and other Southeast Asian countries.In this study, we focused on the influence of microbial activity on Tc behaviour in soil under the waterlogged condition. The microbial activity is expected to be controlled by addition of glucose and the activity causes a change in the soil redox condition. Air-dried soil with increasing glucose contents and sterile soil were used to compare the effect of microbial activity. The soils were waterlogged with99Tc solution. Although the concentrations of99Tc in the surface and bottom solutions of air-dried soils decreased over time with increasing glucose concentration, those of sterile soils were almost constant during the experiment. From these results, it was assumed that the activity of microorganisms influenced Tc adsorption onto the soil.