POTENTIAL REMEDIATION OF CS-137 AND SR-90 CONTAMINTAED SOIL BY ACCUMULATION IN ALAMO SWITCHGRASS

Authors: Entry, James; WATRUD, LIDIA - U.S. EPA

Submitted to: Journal of Water Air and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cesium-137 (Cs-137) and Strontium-90 (Sr-90) are radionuclides characteristic of nuclear fallout from nuclear weapons testing and nuclear reactor accidents. Alamo switchgrass (Panicum virginatum L.) is a perennial species native to central North America that produces exceptionally high biomass yields in short periods of time. In three separate experiments, Alamo switchgrass plants were tested for their ability to accumulate Cs-137 and Sr-90 from a contaminated growth medium. Plants in experiment 1 were grown in 33x20x7 cm plastic pans containing 2.5 kg sand. Plants in experiments 2 and 3 were grown in 30x3 cm diameter test tubes containing 0.3 kg growth medium. After 3 months of plant growth, either 102 Bq Cs-137 or 73 Bq Sr-90 g/1 soil were added to the growth medium. Above-ground plant biomass did not differ between plants that were not exposed to these radionuclides (controls) and those that were exposed to growth medium containing Cs-137 or Sr-90 over the course of the experiment. Plants accumulated 44% and 36% of the total amount of Sr-90 and Cs-137 added to growth medium after the first 5 harvests. After the first two harvests, the concentration of Cs-137 and Sr-90 in plant tissue and the amount of Cs-137 or Sr-90 removed from growth medium declined with each successive harvest. As concentration of both Cs-137 and Sr-90 in growth medium increased, plant accumulation of both radionuclides increased and correlated curvilinearly in seedlings.

Technical Abstract: Cesium-137 (Cs-137) and Strontium-90 (Sr-90) are radionuclides characteristic of nuclear fallout from nuclear weapons testing and nuclear reactor accidents. Alamo switchgrass (Panicum virginatum L.) is a perennial species native to central North America that produces exceptionally high biomass yields in short periods of time. In three separate experiments, Alamo switchgrass plants were tested for their ability to accumulate Cs-137 and Sr-90 from a contaminated growth medium. Plants in experiment 1 were grown in 33x20x7 cm plastic pans containing 2.5 kg sand. Plants in experiments 2 and 3 were grown in 30x3 cm diameter test tubes containing 0.3 kg growth medium. After 3 months of plant growth, either 102 Bq Cs-137 or 73 Bq Sr-90 g/1 soil were added to the growth medium. Above-ground plant biomass did not differ between plants that were not exposed to these radionuclides (controls) and those that were exposed to growth medium containing Cs-137 or Sr-90 over the course of the experiment. Plants accumulated 44% and 36% of the total amount of Sr-90 and Cs-137 added to growth medium after the first 5 harvests. After the first two harvests, the concentration of Cs-137 and Sr-90 in plant tissue and the amount of Cs-137 or Sr-90 removed from growth medium declined with each successive harvest. As concentration of both Cs-137 and Sr-90 in growth medium increased, plant accumulation of both radionuclides increased and correlated curvilinearly in seedlings.