| Abstract: | The Hawkesbury River of New South Wales, Australia is under increasing environmental stress. Pre-anthropogenic and current levels of heavy metal concentrations have been established for bed sediments between Windsor and Broken Bay. Sediment heavy metal concentrations in the main channel of the Hawkesbury River are close to background, but are substantially elevated in the headwaters of Berowra Creek, Cowan Creek and in southeast Pittwater. The Berowra Waters area and the upper catchment contribute both heavy metals and organochlorines/pesticides to the Berowra estuary. High contaminant levels above and below the Hornsby sewage treatment plant, and above and below the Calna Creek sewage treatment plant, make an assessment of the contribution by these plants difficult. Analyses of oyster tissue from the middle and lower reaches of the estuary indicate that heavy metal contaminants are entering the food chain. |
