Assessment of soil contamination around an abandoned mine in a semi-arid environment using geochemistry and geostatistics : pre-work of geochemical process modeling with numerical models

One of the most serious environmental issues related to mining industry in Morocco and elsewhere around the world, is the pollution from abandoned mine sites. Mine wastes cause obvious sources of soil contaminations. Climatic effects such as heavy rainfall engender metal dispersion in semi-arid areas, since soils are typically and scarcely vegetated. In this study, extension and magnitude of soil contaminations with toxic elements from abandoned Kettara mine, in Morocco, are assessed using geochemical analysis and geostatistics for mapping. Soils and mine wastes are sampled and analyzed for 41 chemical elements (Mo, Cu, Pb, Zn, Ag, Ni, Co, Mn, Fe, As, U, Au, Th, Sr, Cd, Sb, Bi, V, Ca, P, La, Cr, Mg, Ba, Ti, Al, Na, K, W, Zr, Ce, Sn, Y, Nb, Ta, Be, Sc, Li, S, Rb and Hf). Based on enrichment factor (EF), only five elements of interest (Cu, Pb, Zn, As, and Fe) were selected in this research. Geochemical background is determined with exploratory data analysis and geochemical maps were elaborated using geostatistics in Geographic Information System (GIS) environment. The obtained results show that Kettara soils are contaminated with metals and metalloid that exceed the established geochemical background values (Cu~43.8mg/kg, Pb~21.8mg/kg, Zn~102.6mg/kg, As~13.9mg/kg and Fe~56,978mg/kg). Geochemical maps show that the deposited mine wastes are responsible for soil contaminations with released metals and metalloid that have been dispersed downstream from the mine waste mainly, through water after rainfall. For sustainable development and environmental planning, the current study is expected to serve as a reference for politicians, managers, and decision makers to assess soil contaminations in abandoned mine sites in Morocco