On the last 200 years the Nalón River estuary has been receiving a continuous apport of materials from the mining and industrial activities developed in the high and medium parts of the hydrographic basin. As consequence of the apports of heavy metals and metalloids to the hydric courses of the area in dissolved and particulate phases, some elements have significantly increased their concentrations with respect to the natural geochemical background. The study of the concentrations by means of reference normalized indices such as the Geoaccumulation Index (Igeo) and the Enrrichment Factor (FE) have pointed out that in different levels of the saltmarsh, elements such as As, Cu, Pb and Zn show concentrations which can be attributed to anthropogenic activities as main sources of apport. Specially significants are the Pb contents, where near the 50% of the analysed samples show anomalous concentrations of this metal which can be attributed to human activities.
