TEXTURAL DISTRIBUTION OF ARSENIC AND HEAVY METALS IN SOILS AFFECTED BY ABANDONED MINING WORKS: CONSEQUENCES FOR SOIL WASHING

8th International Scientific Conference - SGEM2008, www.sgem.org, SGEM2008 Conference Proceedings/ ISBN: 954-918181-2, June 16-20, 2008, Vol. 2, 349-354 pp

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.

Keywords: soil washing, texture, arsenic.