Effects of Chelating Compounds on Mobilization and Phytoextraction of Copper and Lead in Contaminated Soils

Abstract

Six chelating compounds: ethylenediamine-tetraacetic acid (EDTA), ethylenediamine-N, N'-disuccinic acid (EDDS), tartaric acid, citric acid, glycine and histidine, were tested as potential agents to mobilize copper (Cu) and lead (Pb) from two soils polluted with the emissions from copper smelters. Copper was mobilized with the following efficiency: EDTA > citric and tartaric acids > histidine > EDDS and glycine, while Pb extractability followed the order: EDTA > EDDS >> tartaric and citric acid >> glycine and histidine. With respect to these results, EDTA and EDDS were chosen for a pot experiment on chelate-induced phytoextraction of Cu and Pb by maize (Zea mays). Chelates were applied at the rates of 0.2, 0.5, and 1.0 mmol kg−1, and this experiment was carried out at two different watering regimes. Both EDTA and EDDS caused significant increase of Cu uptake from soils, but its concentrations in biomass were far below those required for efficient soil remediation. Lead uptake was only slightly affected by chelate application. Losses of Cu from soil by leaching were much higher than those caused by plant uptake.