Influence of the Loire River on Dissolved Lead and Cadmium Concentrations in Coastal Waters of Brittany

Abstract Two surveys have revealed a significant solubilization of particulate cadmium in the Loire estuary (France). This enrichment of the solution, which does not appear to be linked to any intra-estuarine anthropogenic source, is notable along the entire southern Brittany coastline where mean dissolved cadmium concentrations (0·16 nM) are slightly higher than those observed in northern Brittany (0·12 nM). Lead distribution in the Loire estuary seems to be largely governed by a significant anthropogenic input which completely masks the natural geochemical behaviour of this element. However, the high dissolved lead concentrations (up to 1·7 nM) remain confined to the estuarine zone itself, while the coastal zone presents markedly lower concentrations (0·16 to 0·39 nM). Unlike what may be observed for cadmium, and despite a significant anthropogenic input to the estuary, dissolved lead enrichment in the coastal waters of Brittany therefore seems very confined.