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Potential for phytoextraction of ¹³⁷Cs from a contaminated soil
Mitch M. Lasat, Wendell A. Norvell and Leon V. Kochian
Plant and Soil
Vol. 195, No. 1 (August (I) 1997), pp. 99-106
Published by: Springer
Stable URL: http://www.jstor.org/stable/42949401
Page Count: 8
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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 in ¹³⁷Cs-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 the ¹³⁷Cs.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 speciesdependent 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 of ¹³⁷Cs in the soil could greatly enhance the prospects for the use of plants to remediate ¹³⁷Cs-contaminated soils.
Plant and Soil © 1997 Springer