Heavy metal enrichment in the surface microlayer of the Nepean-Hawkesbury river system

Abstract

Copper, lead, cadmium and zinc have been measured in subsurface and surface-film water samples collected from the Nepean-Hawkesbury river system in New South Wales. Positive correlations were obtained between measured surface-film pressures and the surface excesses of lead, zinc and dissolved organic carbon. Measurements of copper-complexing capacity of the surface samples correlated well with dissolved organic nitrogen data. Enriched zinc was present in the surface film, mainly in bound species, as determined by anodic stripping voltammetry; lead was enriched in both labile and bound forms. Copper was also present in bound species, with many samples being depleted in labile copper. The relative concentrations of these heavy metals in surface films at the different sampling stations could be interpreted on the basis of known inputs.