Effects of Low Molecular Weight Organic Acids on Speciation of Pb in Soil

To investigate the mechanism of chelate-induced phytoremediation,effects of two kinds of low molecular weight organic acids including citric acid and malic acid on chemical speciation of Pb in soil were studied.Results showed that,for different pollution levels of soil(PbⅠ-PbⅣ),percentage of the most active exchangeable Pb increased significantly as concentration of organic acids were increased.So as to achieve the objective of activating Pb;The mobilization effect of Pb would increase along with concentration of citric acid,and with higher concentration of malic acid added,the mobilization effect of Pb first increased then kept on,when malic acid concentration was 10 mmol/kg and citric acid concentration was 20 mmol/kg,activation ability of malic acid and citric acid respectively reached the maximum value.By comparison,activation ability of citric acid was better than malic acid.