Marine pollution in Australia, with special emphasis on central New South Wales estuaries and adjacent continental margin

This paper reviews the current knowledge and environmental status of Austra lian estuaries and continental margins in terms of sedimentary heavy metals . Although only 2.5% of Australian estuaries and 0.1% of the adjacent conti nental shelf have been surveyed for sedimentary heavy metals, some of the m ost contaminated maritime areas in the world have been located in this coun try. The most impacted regions are adjacent to single-purpose industrial co mplexes, e.g. smelters, refineries and chlor-alkali plants, whereas Port Ja ckson (Sydney) is by far the most contaminated mixed urbanized/industrializ ed estuary in Australia. The concentration of metals is substantially highe r and more extensive in Australian estuaries than in sediments of the conti ntental margin. Even the continental margin adjacent to central New South W ales (NSW) where almost one third of the total Australian population live, shows only minor environmental impact. These data demonstrate the effective ness of estuarine environments to act as traps for pollutants, and converse ly, how efficiently contaminants are dispersed from the high energy contine ntal margins of Australia. In central NSW, the level of estuarine contamina tion is closely related to the extent of urbanization/industrialization. Ex tensive areas of Port Jackson are contaminated with heavy metals, especiall y Pb and Zn, and a large proportion of the estuary has sedimentary metals a t concentrations where some adverse biological affects can be expected. Alt hough much of the contamination is a legacy of past poor industrial practic e, high metal concentrations in fluvial sediments entering the harbour indi cate contaminants continue to be supplied to the waterway. There are many p ossible sources, but stormwater and leachates from extensive reclamation at the upper reaches of some tributaries and embayments may be important. The political significance of the coastal zone and the extent of impact on thi s environmental has recently (and belatedly) been realized, and new Commonw ealth investigations and initiatives have been instigated. The first 'State of the Environment of the Marine Environment Report' has been completed an d the 'Commonwealth Coastal Policy' has been initiated. However, the amount and quality of sedimentary contaminant data available in the coastal zone is totally inadequate to construct a national contaminant framework for thi s environment. This lack of good quality, regionally comparable data hinder s the development of appropriate management strategies and construction of legislative structures for the coastal zone.