Heavy metals in a contaminated Australian estuary—Dispersion and accumulation trend

摘要: Very high concentrations of Zn, Pb, Cu and Cd occur in the muddy bottom sediments Lake Macquarie, a saline coastal lagoon southeastern Australia. The trace metals emanate from industrial sources, especially lead-zinc smelter, at northern end lake. Individual metal decrease progressively away source area but differing rates; Zn is most mobile appears to be deposited first. They approach natural background levels southern part Mn shows reverse trend Ni, Co, Ag Fe rarely rise above levels. Shallow cores lake bed penetrated enriched surface zone 15–35 cm thick underlain by uncontaminated with (background) concentrations. Sedimentation rates determined radiocarbon ages on shells mainly range between 0·15 0·5 mm yr−1. Over 85 years since industrialization commenced, less than 5 mud has accumulated bed. Bioturbation invoked account for depth which sediment been heavy metals.