Heavy metal concentrations in consecutive saturation extracts of dredged sediment derived surface soils

Heavy metals in upland, dredged-material disposal sites are of concern. Met al mobility and availability are closely related to the composition of the liquid phase. To appraise changes in pare-water metal concentrations (Cd, C u, Pb, Zn) after continued leaching, surface soil samples from abandoned me tal-contaminated dredged-sediment disposal sites were subjected to consecut ive saturation extracts. For an 'alternatingdry and wet' moisture regime, w here soils were allowed to dry between extractions, metal concentrations va ried randomly in the consecutive extracts. For a 'continuously wet' moistur e regime, metal concentrations decreased when reducing conditions were bein g established and then remained constant at a lower level than in the alter nating dry and wet moisture regime. Potential short-term hazards (15-40 yea rs:) related to metal migration were estimated from the observed leaching b ehavior. Although metal concentrations in the saturation extracts of the ox idized soils were above levels found in the pore-water of clean soils, meta l migration is estimated to be limited. However, an enhanced availability o f Cd, Cu, and Zn for organisms living in these soils must be anticipated. ( C) 1998 Elsevier Science Ltd. All rights reserved.