Effect of coastal cities on surficial sediments mantling an adjacent high-energy continental margin - central New South Wales, Australia

Trace metal (Cd, Co, Cu, Fe, Mn, Ni, Pb, Zn) concentrations in the fine fra ction (<62.5 mu m) of surficial sediments adjacent to the major urban centr es of Sydney, Newcastle and Wollongong on the central New South Wales (NSW) continental margin, Australia, are elevated above regional background. The nature of enrichment off these major urban centres is distinct. The fine f ractions of sediments adjacent to Newcastle are enriched in Cd, Co, Cu, Fe, Mn, Ni, Pb and Zn, associated with the disposal of dredged harbour spoil i n an offshore dumpsite, whereas adjacent to Sydney, enrichment of Cu, Pb an d Zn in the fine fraction of sediments results mainly from the disposal of large volumes of sewage effluent. The source and regional dispersion of tra ce metals an the central-NSW continental margin can only be established fro m analysis of the fine fraction of the sediment, because total sediment dis tributions of contaminants are confounded by a highly variable sediment tex ture. Generally, low mud contents (<2%) and low concentrations of trace met als in inner-shelf sediment are evidence of efficient dispersal of fine mat erial and associated contaminants on this high-energy continental margin.