TRACE-METALS AS TRACERS OF DREDGING ACTIVITY IN CLEVELAND BAY - FIELDAND LABORATORY STUDIES

This study has investigated in detail trace metal concentrations in Cl eveland Bay in the central Great Barrier Reef and assessed the signifi cant carrier phases of several metals during a simulated disturbance o f sediments designed to investigate the effects of dredging. Organic, iron oxide and carbonate phases were shown to be important carrier pha ses for several trace metals. The application of an acid-leach techniq ue to monitor labile or pollutant concentrations of copper, zinc, lead and nickel in sediments collected from coral reefs sampled before and after two dredging events in 1991 yielded useful information on the f ate of dredged sediment. Trace metal contamination close inshore was a ttributed to port activities, sewage discharge and urbanization.