Fraction distribution and leaching behavior of heavy metals in dredged sediment disposal sites around Meiliang Bay, Lake Taihu (China)

Abstract

The objectives of this study were to characterize the heavy metal contamination status of surface soils sampled at two dredged sediment land disposal sites (the Baimao and Kongwan landfills) in Meiliang Bay, Lake Taihu, China, as well as to investigate the effect on their leaching behaviors due to acid rain. Among all the metals, only the nickel content in the Baimao landfill was higher than the Chinese reference value, and all metal contents were below the limit values for agricultural soils. The fraction distribution of metals by sequential extraction was similar at both sites. Cadmium had a relatively high proportion of exchangeable-carbonate fractions, while the other metals were mainly classified as residue fractions. The metals released from soils by simulated rainwater comprised less than 1% of the total soil metal content, and the effect of acid rain on heavy metal release from dredged sediments in land disposal sites was found to be negligible at both sites. All results indicate no environmental concern for the land disposal of dredged sediments and support the feasibility of beneficially reusing dredged sediment soils as a supplement to agricultural soils.