Trace metals distribution in surface and deep seawater from the Ría de Arousa estuary (north-western Spain): Study before and after the Prestige oil tanker sinking

Cu, Ni, Pb, Mn, Sn, Fe, Al and Zn in surface and deep seawater samples from Ría de Arousa estuary (Galicia, north-western Spain) collected before and after the Prestige spillage were determined. Data were then used to evaluate the impact of the Prestige accident in the Ría de Arousa by applying principal component analysis (PCA) and cluster analysis (CA). Surface water from Sar River and Ulla River was also analysed for the same elements. Determinations were performed by inductively coupled plasma–optical emission spectrometry (ICP–OES) after solid phase extraction (SPE) of element-8-hydroxyquinoline complexes onto commercial C18 cartridges. The highest concentrations were found in sampling stations along Ulla River, while Al, Fe and Sn offered the highest values in surface and deep seawater from the inner part of the estuary, area where the main villages and sport harbours are located. PCA and CA have shown an independent group formed by surface seawater from the East margin of the mouth of the estuary collected after the Prestige oil spill. However, independent groups were not observed when using deep seawater data, and the effect of the Prestige accident appears to be less evident.