Analysis of the spatial variation of heavy metals in the Guadiana Estuary sediments (SW Iberian Peninsula) based on GIS-mapping techniques

• Published in: Estuarine, coastal and shelf science Vol. 88; no. 1; pp. 71 - 83
• Main Authors: Delgado, J., Nieto, J.M., Boski, T.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 10.06.2010; Elsevier
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Basins; Biological and medical sciences; Brackish; Brackish water ecosystems; Cadmium; Enrichment; enrichment factor; Estuarine environments; Fundamental and applied biological sciences. Psychology; geochemistry; Geographic information systems; GIS-analysis technique; Guadiana Estuary; Iberian Pyrite Belt; Origins; Pollution abatement; Satellite navigation systems; Sediments; source contamination; Synecology; Iberian Peninsula; Europe; ANE, Europe, Iberian Peninsula, Guadiana Estuary; Europe, Iberian Peninsula, Guadiana R; ANE, Europe, Iberian Peninsula; source contamination; Iberian Pyrite Belt; Guadiana Estuary; geochemistry; GIS-analysis technique; enrichment factor; Brackish water environment; Estuaries; Geochemistry; Sediments; Spatial variation; Contamination; Heavy metal; Pyrite; Geographic information system
• ISSN: 0272-7714; 1096-0015
• DOI: 10.1016/j.ecss.2010.03.011

This work reveals the usefulness of the GIS (Geographic Information Systems) mapping techniques to show the distribution of pollutants along an estuarine environment, as the final stage of a thorough study. In the case of study, the environmental quality of the sediments in the Guadiana river estuary was determined by means of a complete geochemical characterization consisting on the calculation of enrichment factors for the most important metals and metalloids (compared with the local background of non-contaminated sediments). The obtained results were depicted in “enrichment distribution maps” which evidenced a distribution of the elements in two groups: Group-I, elements with natural origin (Al, Fe, Mn, Co, and Cr) distributed homogeneously along the basin, and Group-II, elements associated to anthropic origin (As, Cd, Cu, Pb, Ni and Zn) with clear punctual sources besides a high concentration all over the estuary. The enrichment factors for the elements of Group-II are indicative of the existence of a noticeable diffuse historical mining pollution associated with the acid mine drainage generated in the internal zones of the basin, which could overlap minor pollution inputs from other human activities. The obtained results lead us to a reconsideration of the traditionally thought “unpolluted” environment when it was compared to nearby estuaries.