Metals, acid-volatile sulfides, organics, and particle distributions of contaminated sediments

An overview of key physical/chemical parameters for contaminated sediments is presented. While sediment cores from remote lakes show little or no enrichment with heavy metals (Pb, Hg, Cd, Zn, Cu) and PAHs in top layers, the contamination near industrial areas is more significant. Cd in more bioavailable geochemical phases can occur in response to Cu inputs to sediments, and aeration during dredging operations of anaerobic sediments can reduce the pH causing release of heavy metals. The toxicity of anaerobic sediments to benthos can be effectively predicted based on interstitial water concentrations and the molar ratio between simultaneously extracted metals and acid-volatile sulfides (SEM/AVS). The toxicity of PAHs and other organics can be predicted based on equilibrium partitioning. Principal component analysis indicates that PAHs are associated with organic carbon and silt, and PCBs with inorganic clay. Finally, formulated reference sediments appear to be useful in toxicity testing by creating uniform parameters matching field conditions, and by isolating the effects of specific contaminants. (C) 1998 IAWQ. Published by Elsevier Science Ltd.