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Textural distribution of arsenic and heavy metals in soils affected by abandoned mining works: Consequences for soil washing

Abstract:

We introduce an example of a detailed study of soil texture and geochemistry with the aim of designing appropriate soil washing systems. Concretely, we have studied soils affected by the mining works of "Los Rueldos" (Asturias, Spain). After an initial characterization, composite, representative samples were taken and ICP-MS analysis was carried out. Results showed very high concentrations of As, and significant presence of heavy metals such Hg, Pb and Zn specially in silt-clay fractions obtained after wet sieving. Multivariate statistics revealed a very strong correlation between As-Sb-S-Fe which suggested the association of As with pyrite and ferric oxihydroxides. As consequence of that, soil washing strategies proposed include not only, particle size separation, but also gravity separation in order to take apart sulphur and oxide dense particles from clays and sands.