PHYTOREMEDIATION OF SOIL CONTAMINATED WITH LOW CONCENTRATIONS OF RADIONUCLIDES

Ecosystems throughout the world have been contaminated with radionucli des by aboveground nuclear testing, nuclear reactor accidents and nucl ear power generation. Radioisotopes characteristic of nuclear fission, such as Cs-137 and Sr-90, that are released into the environment can become more concentrated as they move up the food chain often becoming human health hazards. Natural environmental processes will redistribu te long lived radionuclides that are released into the environment amo ng soil, plants and wildlife. Numerous studies have shown that Cs-137 and Sr-90 are not removed from the top 0.4 meters of soil even under h igh rainfall, and migration rate from the top few centimeters of soil is slow. The top 0.4 meters of the soil is where plant roots actively accumulate elements. Since plants are known to take up and accumulate Cs-137 and Sr-90, removal of these radionuclides from contaminated soi ls by plants could provide a reliable and economical method of remedia tion. One approach is to use fast growing plants inoculated with mycor rhizal fungi combined with soil organic amendments to maximize the pla nt accumulation and removal of radionuclides from contaminated soils, followed by harvest of above-ground portion of the plants. High temper ature combustion would be used to oxidize plant material concentrating Cs-137 and Sr-90 in ash for disposal. When areas of land have been co ntaminated with radionuclides are large, using energy intensive engine ering solutions to remediate huge volumes of soil is not feasible or e conomical. Plants are proposed as a viable and cost effective method t o remove radionuclides from the soils that have been contaminated by n uclear testing and nuclear reactor accidents.