Distribution and sources of trace element pollutants in the sediments of the industrialised Port Kembla Harbour, New South Wales, Australia

Abstract

A detailed geochemical analysis of sediment samples from the heavily industrialised Port Kembla Harbour, 70 km south of Sydney in New South Wales, Australia, has delineated areas that are heavily contaminated with trace element pollutants. Local creek delta sand accumulations, basin mud deposits, reclamation deposits and exposed bedrock on the present harbour floor are consistent with the twentieth century Port Kembla industrial land and harbour development history, as well as known maritime shipping practices. The closed electrolytic copper refinery, one of the two major pollutant sources, has provided a very clear signature in the harbour opposite the main drain that discharged from these works. Copper pollution (up to 6070 mg/kg) is strongly correlated with high concentrations of gold, selenium, antimony, arsenic, lead and zinc. These pollutants appear to occur as silt- and sand-sized particulate matter, as well as pollutants that are probably chemically bound to clay, pyrite and organic matter. The second main pollutant source is the BlueScope steelworks that has been responsible for high concentrations of iron (and minor associated cobalt), kish, pyrolytic carbon and fly ash. The steelworks, along with other industrial, urban and automobile sources, supply additional quantities of copper, lead and zinc to the aquatic environment. Coal and coke dust also form important pollutants. The pollutants are currently fairly stable under the prevailing alkaline reducing conditions within the sediment. The proposed future reclamation and dredging within the harbour needs to consider the implications of moving highly contaminated sediment, without altering its alkalinity or oxidation potential, to prevent release of contaminants.