Heavy metals in Morocco Lagoon and river sediments

Analyses of Mn, Cd, Cr, Cu, Pb, and Zn were carried out in a short core from a salt marsh of the Nador Lagoon (north-eastern Morocco) and in surficial sediment samples collected in the Martil river, which borders the industrial town of Tetouan, Three soil samples and a reservoir sediment were also collected around the town to check the effects of atmospheric delivery of contaminants. Cs-137 and Pb-210 activity-depth profiles were used to establish a chronology for the core, obtaining an apparent accumulation rate of 0.41 cm y(-1). The concentrations of anthropogenic metals in this marsh sediment are low and probably represent natural backgrounds. A recent decrease can be an effect of changing grain size. The Martil River sediments are slightly contaminated by Cu and Pb, whereas the soil samples present anomalous values of Cd and Zn.