Geochemical characterization of the surface sediments from the Guadiana river estuary (SW of the Iberian Peninsula)

This work has been developed with the aim of determining the environmental quality of the sediments in the Guadiana river estuary, and evaluating the possible incidence that some processes associated to human activities (acid mine drainage, urban effluents) could produce in this sediments. For this purpose, the geochemical and granulometric characterization of the estuary sediments have been determined, and the enrichment factors have been calculated for the most important metals and metalloids (As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn).The results obtained evidences a distribution of the metals and metalloids in two groups: Group I with elements with a natural origin ( Al, Fe, Mn, Co, Cr and Ni ), and Group II, with elements associated to an anthropic origin ( As, Cd, Cu, Pb and Zn ). The enrichment factors for the elements of the Group II, are indicative of the existence of a diffuse mining contamination, associated with the acid mine drainage of internal zones of the basin. There has been also found out anomalous concentrations of some of these elements near the villages of Ayamonte and Villa Real de Sto Antoni