Trace metal speciation in three Victorian lakes

Abstract

The speciation of the trace metals iron. cadmium. copper, lead and zinc was determined in Lake Tarli Karng, Tarago Reservoir and East Basin Lake using membrane filtration. Chelex resin and dialysis to provide information on particulate, filterable, ion-exchangeable. dialysable and bound metal fractions. The total metal concentrations and distribution between particulate and filterable fractions varied considerably between the three lakes. Two major factors controlling these observed differences will be the water chemistry and the hydrological properties of the lakes. The major proportion of the total cadmium, copper. lead and zinc in each lake was in filterable forms, with a considerable amount of this in ion-exchangeable forms. Free metal ionic species, simple inorganic complexes and organic complexes, including metal-fuivic acid complexes. will be ion-exchangeable. The bound forms of these metals are not known. Iron was found to exist predominantly in bound forms, most probably as particulate and colloidal iron hydroxyoxides, although it is also possible that very strong organic complexes, such as iron hydroxamate siderophores, could also form part of the bound fraction.