Baseline trace metal concentrations in New South Wales coastal waters

Abstract

Concentrations of ten trace elements at five localities in New South Wales coastal waters were measured by ultratrace sampling and analysis. Mean concentrations of cadmium (2.4 ng L-1), copper (31 ng L-1), nickel (180 ng L-1), lead (9 ng L-1) and zinc (<22 ng L-1) are among the lowest reported in the Southern Hemisphere and are consistent with recent oceanographic data for the surface waters of the Pacific Ocean. Waters from the southernmost sampling locality (Eden) contained higher phosphate, silicate, cadmium and nickel, but lower chromium concentrations than waters from the other four localities, reflecting the inputs of water from the Tasman Sea in the south compared with the dominance of waters from the Coral Sea along the rest of the coast. Cadmium concentrations were positively correlated with both phosphate and silicate. Chromium and lead concentrations were also significantly correlated. It is likely that a major source of lead is atmospheric deposition. The trace metal concentrations were comparable to those in the surface waters of the Pacific Ocean, indicating that fluvial inputs or processes occurring in the coastal margin were of limited importance in determining trace metal concentrations.