Environmental geochemical mapping of Huelva municipality soils (SW Spain) as a tool to determine background and baseline values

At present, environmental geochemical cartography using GIS-GeoDAS combined software has become an important tool in the study of polluted soils. Huelva Township, where several sources of pollution (related to acid mine drainage, industrial complexes, urban wastes…) take place is a singular environment to determine the geogenic natural content (background) and the anthropogenic contribution (baseline) applying the GIS-GeoDAS analysis. For this purpose, 150 surficial soil samples and 6 soil profiles were collected and analyzed using ICP-MS and ICP-ES for major and trace elements. The statistic analysis and the background values established have allowed to discriminate two ground of elements: a) anthropic sources (F1: Ag, As, Cd, Cu, Pb, Zn and Hg, among others) and b) natural sources (F2: mainly Al, Co, Cr, Ni, V and Be). Additionally, baseline maps show several elements sources related to AMD processes in the floodplain of the Tinto–Odiel estuary (As, Cd, Cu, Pb, and Zn, among others) and also associated with those areas where intense industrial activity has been developed. Arsenic, Cd, Cu, Pb, Ag and Zn baselines values are above the threshold values recommended by the Directive Commission of the European Community for soils and sludge and therefore represent a risk to human health. The established background and baseline values by GIS-GeoDAS could be used as generic values for the proper application of environmental soil regulations in the future.

Research highlights
► Background values has been established for the Huelva municipality soils.
► Factor analysis of trace metals in soils clearly show geogenic and antrhopogenic sources.
► Multifractal IDW interpolation is also a powerful tool to determine soil pollutant sources.
► Concentration levels for some elements exceed the limits of European legislation.