Arsenic and metal mobility from Au mine tailings in Rodalquilar (Almería,SE Spain) |
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Authors: | Andrés Navarro Flores Luis Miguel Doménech Rubio |
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Institution: | 1.Departamento M. Fluidos, ETSEIAT,Universidad Politécnica de Catalu?a (UPC),Terrassa,Spain |
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Abstract: | In the old mining area of Rodalquilar, mine wastes, soil and sediments were characterized and the results revealed high concentration
of Au, Ag, As, Bi, Cu, Fe, Mn, Pb, Se, Sb and Zn in tailings and sediments. The contaminant of greatest environmental concern
is As. The mean concentration in the tailings was 679.9, and 345 mg/kg in the sediments of Playazo creek. The groundwater
samples from the alluvial aquifer showed high concentration of Al, As, Cd, Fe, Hg, Mn, Ni, Pb, Se, Sb and Zn and very high
concentration of chloride and sulfate, which were above the concentration defined in the European standards for drinking water.
The presence of As in groundwater may be caused by the oxidation of arsenian pyrite, the possible As desorption from goethite
and ferrihydrite and the jarosite dissolution. Groundwater concentrations of Cd, Fe, Mn, and possibly Cu, were associated
with low values of Eh, indicating the possible dissolution of oxy-hydroxides of Fe and Mn. The mobility of metals in the column
experiments show the release of Al, Fe, Mn, Cr, Cu, Ni, V and Zn in significant concentrations but below the detected values
in groundwater. However, As, Cd, Sb, Se Pb and Au, are generally mobilized in concentrations above the detected values in
groundwater. The possible mass transfer processes that could explain the presence of the contaminants in the aquifer and the
leachates was simulated with the PHREEQC numerical code and revealed the possible dissolution of the following mineral phases:
jarosite, natrojarosite, arsenian pyrite, alunite, chlorite, kaolinite and calcite. |
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