Effects of organic acids on zinc and lead leaching from contaminated sediments.

The leaching characteristics of zinc and lead in two contaminated sediments were studied, and the effect of low molecular weight organic acids (LMWOAs) and pH value on the leaching of zinc and lead from two contaminated sediments were examined. The results showed that zinc and lead in the sediments were partly dissolved by three LMWOA solutions under different concentrations in batch experiment. The leaching of heavy metals from two sediments followed the descending order: citric acid malic acid tartrate acid (for zinc); citric acid tartrate acid malic acid (for lead). The leaching concentrations of heavy metals in solution were enhanced with the increasing of LMWOA concentration and the decreasing of pH value. In addition, all LMWOAs leached more heavy metals than inorganic salt did. The leaching capability under the condition of LMWOAs followed the order: zinclead.