Geochemistry of trace metals in the Scheldt estuary

Abstract

The distribution of trace metals has been studied in abiotic compartments of the ScheIdt estuary (water column and sediments). Seasonal surveys, carried out in 1987-1988, indicate that the geochemistry of dissolved trace metals (Cd, Cu, Zn) is determined by the redox status of the upper estuary, and by primary production in the lower estuary. During the warmer period (spring till autumn), the incoming river water is anoxic, leading to very low dissolved metal concentrations due to precipitation of metal sulphides. During winter, the river water is usually not completely devoid of oxygen (although highly undersaturated), precluding metal sulphide precipitation. Therefore, the dissolved metal concentrations in the incoming river water are much higher during winter.