Water-sediment geochemical processes influencing As, Pb, Zn, Cu and Fe mobilization were investigated in a river within the historic mining area of Taxco, Mexico. Tailings wash off and acid mine drainage have led to concentrations of metals in sediments well above the regional background. Zinc and lead associate with the carbonate fraction, followed by Fe oxi-hydroxides. Arsenic and Fe concentrate in the residual fraction, followed by organic matter/sulphide and Fe oxi-hydroxides. Metals are mainly transported as particulates in the water. Calcium, silicate and iron minerals are oversaturated in the river water. Limestones playa key role in the contaminant behaviour. Principal components analysis indicated that Zn, Cu and Pb may be released to the water following small changes in physico-chemical and/or hydrogeological conditions. Application of straightforward analytical techniques jointly with geochemical and statistical evaluation, is an affordable alternative to clarify the environmental impact of mining wastes in developing countries.
Mining, Contamination, Metals, River, Sediments, Mexico, Hydrogeochemistry, Principal components, Limestones, Taxco
