, Volume 195, Issue 1, pp 99-106

Potential for phytoextraction of137 Cs from a contaminated soil

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Abstract

Potential for phytoremediation of a soil contaminated with radiocesium was investigated in three phases: (1) hydroponic screening for plant species capable of accumulating elevated levels of cesium in shoots, (2) investigation of several amendments for their potential to increase the bioavailability of 137Cs in the contaminated soil, and (3) bioaccumulation of radiocesium in shoots of plants grown in137 Cs-contaminated soil.

The bioaccumulation ratio for Cs in shoots of hydroponically grown plants ranged between 38 and 165. From solution, dicot species accumulated 2- to 4-fold more cesium in shoots than grasses. In studies investigating the bioavailability of 137Cs in aged contaminated soil, ammonium salts were found to be the most effective desorbing agents, releasing approximately 25% of the137 Cs. The extent of 137Cs desorption from the soil increased with ammonium concentration up to 0.2 M. In a pot study conducted in a greenhouse, there was significant species-dependent variability in the ability to accumulate 137Cs in the shoot from contaminated soil. The ability to accumulate 137Cs from the soil increased in the order: reed canarygrass (Phalaris arundinacea) < Indian mustard (Brassica juncea) < tepary bean (Phaseolus acutifolius)< cabbage (B. oleracea var. capitata). It was also found that addition of NH4NO3 solution to the soil elicited a two- to twelve-fold increase in 137Cs accumulation in the shoot. The greatest amount of 137Cs (40 Bq g-1 dw) was removed in shoots of cabbage grown in contaminated soil amended with 80 mmols NH4NO3 kg-1 soil. Bioaccumulation ratios of 2–3 were obtained with the best performing plant species. These values are significantly greater than those previously reported in the literature (usually <0.1) for plants grown on aged contaminated soil. These results indicate that careful species selection along with amendments that increase the bioavailability of137 Cs in the soil could greatly enhance the prospects for the use of plants to remediate 137Cs-contaminated soils.