Influence of organic amendments on the accumulation of 137Cs and 90Sr from contaminated soil by three grass species

Bahia grass (Paspalum notatum), johnson grass (Sorghum halpense) and switchgrass (Panicum virginatum) were compared for their ability to accumulate Cs-137 and Sr-90 from three different contaminated soils in the presence and absence of either sphagnum peat or poultry litter amendments. Above-ground plant biomass did not differ between plants that were not exposed to these radionuclides and those that were exposed to soil containing Cs-137 or Sr-90. After three harvests, bahia, johnson and switchgrass plants accumulated from 17.2 to 67.3% of the Cs-137 and from 25.1 to 61.7% of the Sr-90 added to the soil. Poultry litter and peat moss amendments increased aboveground plant biomass, activity of Cs-137 or (9)0Sr in plant tissue, % accumulation of Cs-137 or Sr-90 from soil and the plant bioconcentration ratio at each harvest compared to the control (no amendment) treatment. The greatest increases in plant biomass, and radionuclide accumulation were observed with poultry litter for each of the three grass species. Johnson grass had greater aboveground plant biomass, activity of Cs-137 and Sr-90 in plant tissue, % accumulation of Cs-137 or Sr-90 from soil and bioconcentration ratio in each soil amendment, at each harvest compared to bahia and switchgrass. The greatest accumulation of Cs-137 and Sr-90 was measured in johnson grass grown in soil that was amended with poultry litter. These results suggest that plant species selection and agronomic practices may need to be considered to maximize phytoremediation of radionuclide contaminated soils.