Distribution of heavy metals in dissolved, particulate and biota in the Scheldt estuary, Belgium

Abstract

The distribution of heavy metals in abiotic phases (dissolved, particulate) and biotic fauna (i.e. Mytilus edulis), were analysed and studied in the Scheldt estuary, with the aim of determining the distribution of heavy metal pollution, at seven sites. For the analysed metals, the concentrations in M. edulis tissues were in the order: Fe > Zn > Cu > Pb > Cd > Co. Cadmium concentrations were the lowest for all sites, except at Borsele and Hansweert. The metals in mussel tissues correlated well with metals in both the particulate (e.g. Cd, r = 0.98) and dissolved phases (e.g. Cd, r = 0.57; Cr, Zn, r = 0.79; Fe, r = 0.58). Furthermore, a relationship between heavy metal concentrations in the abiotic phases and the soft tissue of M. edulis was developed, with an effort to determine how much pollution apportionment each abiotic phase contributed to metal accumulation in the soft tissues. Results showed that the contribution from the dissolved phase was more significant compared to the particulate phase. The bioaccumulated heavy metals (e.g. Cd, Cu, Zn) in the tissues were way above the acceptable limits stipulated by international codes of practice, implying critical estuary pollution in the biota.