Spatial and temporal variability of particulate trace metals in Port Jackson Estuary, Australia

Major elements (Al, Ca, Fe and Mn) and trace elements (Cu, Cr, Pb, Zn and N i) in operationally defined available and total particulate phases have bee n determined along an axial transect of the Port Jackson Estuary during twe lve surveys between 1998 and 1999. Salinity, temperature, pH, dissolved oxy gen and suspended particulate material (SPM) were also measured. Temporal a nd spatial variability were tested by two-factor analysis of variance. Thro ughout the estuary Zn and Ni exhibited a uniform distribution. It is sugges ted that the low reactivity of these elements may be a result of the water physicochemistry, low SPM concentrations and long residence time in the Por t Jackson Estuary. Anthropogenic sources of Zn and Ni are widespread in the Port Jackson catchment, and also contribute to the spatial distribution ob served in the estuary. The distributions of particulate Cu and Pb are signi ficantly affected by anthropogenic inputs, particularly, from the southern embayments in the lower estuary. It is suggested that the increase of Cu an d Pb seaward is also related to sorption of these elements on Fe-Mn oxides. Mixing, however, can largely account for the distribution of Cr, which was the only element that presented significant decrease in concentration with increasing salinity. Embayments and tributaries of Port Jackson show disti nctive signatures of particulate trace metals (Cu, Pb and Cr), as a result of anthropogenic activities around those embayments. The SPM composition ha s a significant seasonal variability (P less than or equal to0.05). During spring and summer, the particulate trace metals (Cr, Cu, Pb, Zn and Cr) and major elements (Al and Fe) concentrations are significantly lower than win ter. This trend is ascribed to a dilution effect of plankton blooms on SPM composition. (C) 2001 Academic Press.