CONTAMINATION ASSESSMENT AND RELEASE KINETICS OF HEAVY METALS IN SEDIMENTS OF URBAN-RURAL ECOTONES

摘要

Heavy metal contamination of rivers in urban-rural ecotones is of significant interest in the process of rapid urbanization. Heavy metal contamination was assessed, and heavy metal release kinetics were analyzed for the surficial sediment of the Jiangan River lying in the urban-rural ecotone of Chengdu. Heavy metal concentrations (Cu, Pb, Cr, Ni, Mn, Zn, and Cd) were determined for sediment samples taken from four sites using the atomic absorption method. The heavy metal contamination of the river was assessed using the geo-accumulation index method. The sediment samples from the three sites were polluted by Zn and Cu. The amounts of Zn and Cu released from the sediments to the water were minimal, and the release occurred under acidic conditions. The released amount decreased with increasing pH value until pH 4. A large sediment size releases a large amount of heavy metals. The quantity of released Zn was more than that of released Cu. The release kinetics can be described by the double constant and Elovich equations. The release characteristics of heavy metals from sediments in urban-rural ecotones are similar with those in urban ecotones.