Geochemistry of leachates from the El Fraile sulfide tailings piles in Taxco, Guerrero, southern Mexico
Leachates from the El Fraile tailings impoundment (Taxco, Mexico) were monitored every 2 months from October 2001 to August 2002 to assess the geochemical characteristics. These leachates are of interest because they are sometimes used as alternative sources of domestic water. Alternatively, they drain into the Cacalotenango creek and may represent a major source of metal contamination of surface water and sediments. Most El Fraile leachates show characteristics of Ca–SO4, (Ca+Mg)–SO4, Mg–SO4 and Ca–(SO4+HCO3) water types and are near-neutral (pH=6.3–7.7). Some acid leachates are generated by the interaction of meteoric water with tailings during rainfall events (pH=2.4–2.5). These contain variable levels of SO4 2− (280–29,500 mg l−1) and As (<0.01–12.0 mg l−1) as well as Fe (0.025–2352 mg l−1), Mn (0.1–732 mg l−1), Zn (<0.025–1465 mg l−1) and Pb (<0.01–0.351 mg l−1). Most samples show the highest metal enrichment during the dry seasons. Leachates used as domestic water typically exceed the Mexican Drinking Water Guidelines for sulfate, hardness, Fe, Mn, Pb and As, while acidic leachates exceed the Mexican Guidelines for Industrial Discharge Waters for pH, Cu, Cd and As. Speciation shows that in near-neutral solutions, metals exist mainly as free ions, sulfates and bicarbonates, while in acidic leachates they are present as sulfates and free ions. Arsenic appears as As(V) in all samples. Thermodynamic and mineralogical evidence indicates that precipitation of Fe oxides and oxyhydroxides, clay minerals and jarosite as well as sorption by these minerals are the main processes controlling leachate chemistry. These processes occur mainly after neutralization by interaction with bedrock and equilibration with atmospheric oxygen.
KeywordsAcid mine drainage Arsenic Fe oxyhydroxides Heavy metals Mexico Leachates Speciation
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OTM is very grateful to Elvia Díaz V. for invaluable help and encouragement along all stages of the research. We thank Raina Maier for useful comments and English assistance. Critical comments and suggestions by two anonymous reviewers greatly helped to improve the manuscript, This research was founded by a CONACyT (Consejo Nacional de Ciencia y Tecnología) grant (G28975T).
- Armienta MA, Talarera O, Villaseñor G, Espinosa E, Pérex-Martínez I, Cruz O, Ceniceras N, Agnayo A. 2004, Environmental behaviour of metals from tailings in shallow rivers : Taxco, central Mexico. Appl Earth Sci (Trans Inst Min Metal B) 113, B76–B82Google Scholar
- Bahena-Pita, N. 2003, Evaluación de la calidad del agua de uso doméstico en Taxco el Viejo, Guerrero. BSc thesis, Universidad Autónoma de Guerrero, MexicoGoogle Scholar
- Ball JW, Nordstrom DK. 1991, User’s manual for WATEQ4F, with revised thermodynamic data base and test cases for calculating speciation of major, trace and redox elements in natural waters. U.S. Geological Survey file report, pp 91–183. Google Scholar
- Campa U.M.F., Ramírez E.J. 1979, La evolución geológica y la metalogénesis del noroccidente de Guerrero Serie Técnico-Científica. Universidad Autónoma de Guerrero 1:101Google Scholar
- Castrode Dios M. 2001, Caracterización químico-mineralógica de los sedimentos de los ríos Taxco y Cacalotenango en la región minera de Taxco de Alarcón, Guerrero. BSc thesis, Universidad Autónoma de Guerrero, MéxicoGoogle Scholar
- Consejo de Recursos Minerales (CRM) 1999, Monografía Geológico-Minera del estado de Guerrero. CRM, MéxicoGoogle Scholar
- Dold B. 1999, Mineralogical and geochemical changes of copper flotation tailings in relation to their original composition and climatic setting – Implications for acid mine drainage and element mobility Terre Environ 18: 230 Google Scholar
- Drever J.I. 1997, The geochemistry of natural waters: surface and groundwater environments. Prentice Hall, New JerseyGoogle Scholar
- Flores-Mundo N. 2002, Caracterización químico-mineralógica de los Jales El Fraile, Taxco de Alarcón. BSc thesis, Universidad Autónoma de Guerrero, MexicoGoogle Scholar
- Förstner U. 1983, Metal transfer between solid and aqueous phases In: Förstner U, Wittmann GTW (eds). Metal pollution in the aquatic environment, 2nd edn. Springer, Berlin Heidelberg New York, pp 197–270Google Scholar
- Jambor J.L., Owens D.R. 1993, Mineralogy of the tailings impoundment at the former edge of Sudbury Structure, Ontario. CANMET Div. Rep. MSL93-4 (CF), Department of Energy and Mine Research, CanadaGoogle Scholar
- Langmuir D. 1997, Aqueous environmental geochemistry. Prentice Hall, New JerseyGoogle Scholar
- Nordstrom DK. 1982, Aqueous pyrite oxidation and the consequent formation of secondary iron minerals. In Kittrick JA, Fanning DS, Hossner LR, eds. Acid Sulphate Weathering. Soil Science Society of America, Special Publ. 10: 37–56Google Scholar
- Parkhurst DL. 1995, User’s guide to Phreeqc – A computer program for speciation, reaction-path, advective-transport, and inverse geochemical calculations. U.S. Geological Survey, USAGoogle Scholar
- Ritcey G.M. 1989, Tailings management: problems and solutions in the mining industry. Elsevier, AmsterdamGoogle Scholar
- Talavera Mendoza O., Yta M., Moreno-Tovar R., Dótor-Almazán A., Flores-Mundo N., Duarte-Gutiérrez C.: 2005, Mineralogy and geochemistry of sulfide-bearing tailings from silver mines in the Taxco, Mexico area to evaluate their potential environmental impact. Geofisica Int 44:49–64Google Scholar