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Sökning: WFRF:(Cumbal Luis)

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1.
  • Bundschuh, Jochen, et al. (författare)
  • One century of arsenic exposure in Latin America : A review of history and occurrence from 14 countries
  • 2012
  • Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 2-35
  • Forskningsöversikt (refereegranskat)abstract
    • The global impact on public health of elevated arsenic (As) in water supplies is highlighted by an increasing number of countries worldwide reporting high As concentrations in drinking water. In Latin America, the problem of As contamination in water is known in 14 out of 20 countries: Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, Ecuador, El Salvador, Guatemala, Honduras, Mexico, Nicaragua, Peru and Uruguay. Considering the 1 0 mu g/L limit for As in drinking water established by international and several national agencies, the number of exposed people is estimated to be about 14 million. Health effects of As exposure were identified for the first time already in the 1910s in Bellville (Cordoba province, Argentina). Nevertheless, contamination of As in waters has been detected in 10 Latin American countries only within the last 10 to 15 years. Arsenic is mobilized predominantly from young volcanic rocks and their weathering products. In alluvial aquifers, which are water sources frequently used for water supply, desorption of As from metal oxyhydroxides at high pH (>8) is the predominant mobility control; redox conditions are moderate reducing to oxidizing and As(V) is the predominant species. In the Andes, the Middle American cordillera and the Transmexican Volcanic Belt, oxidation of sulfide minerals is the primary As mobilization process. Rivers that originate in the Andean mountains, transport As to more densely populated areas in the lowlands (e.g. Rimac river in Peru, Pilcomayo river in Bolivia/Argentina/Paraguay). In many parts of Latin America, As often occurs together with F and B; in the Chaco-Pampean plain As is found additionally with V. Mo and U whereas in areas with sulfide ore deposits As often occurs together with heavy metals. These co-occurrences and the anthropogenic activities in mining areas that enhance the mobilization of As and other pollutants make more dramatic the environmental problem.
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2.
  • Lopez, Dina L., et al. (författare)
  • Arsenic in volcanic geothermal fluids of Latin America
  • 2012
  • Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 57-75
  • Tidskriftsartikel (refereegranskat)abstract
    • Numerous volcanoes, hot springs, fumaroles, and geothermal wells occur in the Pacific region of Latin America. These systems are characterized by high As concentrations and other typical geothermal elements such as Li and B. This paper presents a review of the available data on As concentrations in geothermal systems and their surficial discharges and As data on volcanic gases of Latin America. Data for geothermal systems in Mexico, Guatemala, Honduras, El Salvador, Nicaragua, Costa Rica, Ecuador, Bolivia, and Chile are presented. Two sources of As can be recognized in the investigated sites: Arsenic partitioned into volcanic gases and emitted in plumes and fumaroles, and arsenic in rocks of volcanic edifices that are leached by groundwaters enriched in volcanic gases. Water containing the most elevated concentrations of As are mature Ma-Cl fluids with relatively low sulfate content and As concentrations reaching up to 73.6 mg L-1 (Los Humeros geothermal field in Mexico), but more commonly ranging from a few mg L-1 to tens of mg L-1. Fluids derived from Na-Cl enriched waters formed through evaporation and condensation at shallower depths have As levels of only a few mu g L-1. Mixing of Na-Cl waters with shallower meteoric waters results in low to intermediate As concentrations (up to a few mg L-1). After the waters are discharged at the ground surface, As(III) oxidizes to As(V) and attenuation of As concentration can occur due to sorption and co-precipitation processes with iron minerals and organic matter present in sediments. Understanding the mechanisms of As enrichment in geothermal waters and their fate upon mixing with shallower groundwater and surface waters is important for the protection of water resources in Latin America.
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