Geochemistry of major and trace elements in sediments of the Ria de Vigo (NW Spain): an assessment of metal pollution

Ria de Vigo is a funnel-shaped, fault-bounded coastal embayment in Galicia, NW Spain. There are a number of important centres of population and indust rial activity along its margins, which serve as sources of pollution. Sixty -six subtidal sediment samples have been collected in the Ria, The samples have been subjected to a total digestion technique and analysed for major a nd trace elements (Al, Fe,Ti, Mn, Cu, Pb, Cr, Zn, Co, As, Ni, Cd and Sr). V ariations of absolute metal concentrations reflected variations in textural and/or carbonate and organic matter content. Geoaccumulation indexes and e nrichment factors have been calculated to assess whether the concentrations observed represent background or contaminated levels. It is proved that th e choice of the background plays an important role in the interpretation of the geochemical data. PCA was a very useful tool to define background valu es for metals in the Ria de Vigo area. These values were similar to regiona l values given by other authors. It is concluded that the Ria is slightly t o moderately polluted for some of the studied metals. The spatial extent of pollution was examined, and it was found that the most polluted area is lo cated in the inner and southern parts of the Ria, (C) 2000 Elsevier Science Ltd. All rights reserved.