Water Quality and Sediment Behaviour of the Future: Predictions for the
21st Century (Proceedings of Symposium HS2005 at IUGG2007, Perugia, July
2007). IAHS Publ. 314, 2007, 155-162
Assessing
water–sediment processes for metals in rivers polluted by mining to predict
environmental impacts in developing countries
M. AURORA Armienta1, AZUCENA Dótor1, FLOR E. Arcega-Cabrera2, OSCAR
Talavera3, ALEJANDRA Aguayo1, NORA
Ceniceros1 & OLIVIA Cruz1
1 Instituto de Geofísica, Universidad Nacional
Autonoma de Mexico, Circuito Exterior, CU, México 04510 DF, México
victoria@geofisica.unam.mx
2 Posgrado en Ciencias del Mar y Limnología,
Universidad Nacional Autonoma de Mexico, CU, México 04510 DF, México
3 Escuela Regional de Ciencias de la Tierra,
UA de Guerrero, Taxco El Viejo, Guerrero, México
Abstract Water–sediment geochemical processes influencing As, Pb, Zn, Cu and Fe mobilization were investigated in a river within the historic mining area of Taxco, México. 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 play a 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.
Key
words mining; contamination; metals; river;
sediments; Mexico; hydrogeochemistry; principal components; limestones; Taxco