Trace metals and organochlorines in sediments near a major ocean outfall on a high energy continental margin (Sydney, Australia)

Sewage effluent from a large ocean outfall south of Sydney, southeastern Au stralia, is efficiently dispersed on this high energy continental margin. A n enrichment of Ag, Cu, Pb and Zn is only detectable in the fine fraction ( < 62.5 mu m) of sediment. Ag, Co, Cu, Ni, Pb and Zn in the bulk sample corr elate strongly with the mud content of surficial sediment, making an identi fication of the anthropogenic trace metal source difficult using total sedi ment analyses. The concentrations of HCB and DDE in the total sediment are also slightly elevated near the outfall. In the vicinity of the outfall, th e estimated sewage component in the fine fraction of sediment, using AS, Cu and Zn in a conservative, two-endmember physical mixing model, is < 5% and is < 0.25% of the total sediment. A greater anthropogenic Pb component in the fine fraction (mean: 24.8%) of surficial sediment compared to Ag, Cu an d Zn may suggest a source other than sewage to Sydney continental margin se diments. (C) 2000 Elsevier Science Ltd. All rights reserved.