Geochemical mapping, environmental assessment and Pb isotopic signatures of geogenic and anthropogenic sources in three localities in SW Spain with different land use and geology

The Huelva Province located in the southwest of Spain has a long history of mining, industry and agriculture. These anthropogenic activities have a potential environmental impact, with the dispersion of chemical elements in soils and water, and a potential negative effect on the food production and human health. In this study, the concentration of harmful chemical elements in the soil of three case study areas in the Huelva Province are analyzed and related with the land use and local geology. These study areas correspond to the agricultural Aroche village, mining el Campillo site and urban and industrial in the town of Huelva. Topsoil samples have been collected and analyzed by ICP-MS. The analytical results have been used to calculate geochemical maps for As, Cd, Co, Cr, Cu, Hg, Ni, Pb and Zn. Also, the background ranges for these elements and the environmental limits suggested by the Andalusia Government have been used to calculate the contamination factor and pollution index, useful to identify the areas that represent a risk for the population. Finally, lead isotopic analysis of topsoil samples have been carried out, to identify the geogenic and anthropogenic origin of the geochemical anomalies detected in the three study areas. Similarly, human hair samples of donators living in these areas have been analyzed for lead isotopes, to trace the diffusion of selected harmful chemical elements through the tropic chain. The study shows that anomalies of harmful elements are present in the topsoil of the three areas, even in the rural Aroche site, where neither industrial nor mining activities occur. The spatial distribution of those geochemical anomalies is associated to the local geology and land use. Lead isotopic analysis evidenced two well defined signatures of the contamination sources in topsoil and human hair, one related to ore deposits and mining and the other to pesticides and gasoline lead sources.