Behaviour of dissolved Cd, Cu, Pb and Zn in the estuarine zone of the Ferrol Ria (Galicia, NW Iberian Peninsula)

Abstract

The behaviour of dissolved Cd, Cu, Pb and Zn was studied during estuarine mixing in the Grande de Xubia Estuary (Ferrol Ria) in four surveys during 2000 from low-to-high freshwater discharges. Concentrations of metals in the freshwater end-member were within the range of World uncontaminated rivers. All the metals showed a clear deviation from conservative mixing resulting in a net addition within the estuary. Typical concentrations within the estuary (0<Salinity<35) were found to be in the range of 0.50 ± 0.19 nM for Cd, 1.05 ± 0.50 nM for Pb, 34 ± 12 nM for Cu and 71 ± 46 nM for Zn. The relative importance on this net addition by processes such as the discharge of contaminated streams within the estuary or the release from resuspended metal-rich bed sediments is discussed.