Possible biological significance of contaminated sediments in Port Jackson, Sydney, Australia.

Comprehensive investigations of estuaries in central New South Wales has identified Port Jackson as the most contaminated waterway on the eastern seaboard of Australia. Extensive areas of the estuary are mantled in sediment containing high concentrations of a large range of metallic and organic contaminants. Although extensive, this database does not provide an effective basis for determining the potential adverse effects of chemicals on living resources. In the absence of any ecotoxicological information, the recently published (1999) draft Australian and New Zealand Environmental and Conservation Council (ANZECC) sediment quality guidelines have been used to assess possible adverse biological effects of these toxicants. The ANZECC guidelines use the lower effects range of the widely used U. S. National Oceanic and Atmospheric Administration (NOAA) scheme to identify potentially contaminated sediment and as a threshold to trigger for additional investigative work. This guideline level has been used in the current study to assess possible toxicity of contaminated sediments in Port Jackson. It is estimated that sediments in approximately 26% of the estuary, mainly the upper parts of the harbour and much of the central harbour, have a 67% probability of being toxic. Sediments in the central harbour and a major tributary, the Middle Harbour, comprising about 40% of the estuary, have a 13 to 25% probability of toxicity. All sediments in the harbour, except at the mouth of the estuary, would require additional environmental assessment based on the proposed draft ANZECC sediment quality guidelines.