Entry, James A., and Lidia S Watrud. 1998. Potential remediation of 137Cs and 90Sr contaminated soil by accumulation in alamo switchgrass. Water, Air, and Soil Pollution 104:339-352.
Cesium-137 (137Cs) and Strontium-90 (90Sr) are radionuclides characteristic of nuclear fallout from nuclear weapons testing and nuclear reactor accidents. Alamo switchgrass (Panicum virginatum L.) is a perennial C4 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 137 Cs and 90Sr 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 137Cs or 73 Bq 90Sr g-1 soil were added to the growth medium. Plants in all three experiments were grown within a greenhouse that was maintained at 22 ± 2oC with a photosynthetic active radiation of 400-700 µmol m-2 s-1 and a 14-16 h photoperiod. 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 137Cs or 90Sr over the course of the experiment. Plants accumulated 44% and 36% of the total amount of 90Sr and 137Cs added to growth medium after the first 5 harvests. After the first two harvests, the concentration of 137Cs and 90Sr in plant tissue and the amount of 137Cs or 90Sr removed from growth medium declined with each successive harvest. Duration of exposure correlated curvilinearly with accumulation of both 90Sr and 137Cs by plants (r2 = 0.95 and 0.78, respectively). As concentration of both 137Cs and 90Sr in growth medium increased, plant accumulation of both radionuclides increased and correlated curvilinearly in seedlings (r2 = 0.83 and 0.89 respectively).