Distribution of cadmium in cockburn sound, Western Australia

Abstract

The stable isotope technique has been used to measure the distribution of cadmium in Cockburn Sound, a sheltered body of water south of the port of Fremantle in Western Australia. Water samples were collected from approximately 50 positions in Cockburn Sound and the open ocean on three separate occasions in 1978–1979. Although the Sound is an important recreational area, it has become the site of an extensive industrial complex. The major source of cadmium is a fertiliser plant which discharges approximately 4.5 kg of cadmium each day into the Sound. The cadmium from this discharge point has been used as a tracer to investigate the water circulation pattern in the Sound. Because of the sheltered nature of the Sound, the water currents are low, and conventional current-metering techniques are ineffective. Measurements of cadmium concentrations in the summer of 1978 showed that the circulation pattern is dominated by a series of large eddies, which effectively contain the water within the Sound, so that there is only a limited exchange of water with the open sea. Measurements made during the winter period in 1979 confirmed that effective flushing of the Sound had not been achieved, and the consequent build-up of cadmium in the Sound is therefore of major concern.