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- Bundschuh, Jochen, et al.
(författare)
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One century of arsenic exposure in Latin America : A review of history and occurrence from 14 countries
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 2-35
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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. |
- Nicolli, Hugo B., et al.
(författare)
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Arsenic and associated trace-elements in groundwater from the Chaco-Pampean plain, Argentina : Results from 100 years of research
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 36-56
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Forskningsöversikt (refereegranskat)abstract
- The Chaco-Pampean plain, Argentina, is a vast geographical unit (1,000,000 km(2)) affected by high arsenic (As) concentrations in universal oxidizing groundwater. The socio-economic development of the region is restricted by water availability and its low quality caused by high salinity and hardness. In addition, high As and associated trace-elements (F, U, V. B, Se, Sb, Mo) concentrations of geogenic origin turn waters unsuitable for human consumption. Shallow groundwater with high As and F concentrations (ranges: <10-5300 mu g As/L; 51-7,340 mu g F/L) exceeding the WHO guideline values (As: 10 mu g/L; F: 1,500 mu g/L) introduces a potential risk of hydroarsenicism disease in the entire region and fluorosis in some areas. The rural population is affected (2-8 million inhabitants). Calcareous loess-type sediments and/or intercalated volcanic ash layers in pedosedimentary sequences hosting the aquifers are the sources of contaminant trace-elements. Large intra and interbasin variabilities of trace-element concentrations, especially between shallow and deep aquifers have been observed. All areas of the Chaco-Pampean plain were affected in different grades: the Chaco-Saltena plain (in the NNE of the region) and the northern La Pampa plain (in the center-south) have been shown the highest concentrations. The ranges of As and F contents in loess-sediments are 6-25 and 534-3340 mg/kg, respectively in the Sali River basin. Three key processes render high As concentrations in shallow aquifers: i) volcanic glass dissolution and/or hydrolysis and leaching of silicates minerals hosted in loess; ii) desorption processes from the surface of Al-, Fe- and Mn-oxi-hydroxides (coating lithic fragments) at high pH and mobilization as complex oxyanions (As and trace elements)in Na-bicarbonate type groundwaters; and iii) evaporative concentration in areas with semiarid and arid climates. Local factors play also an important role in the control of high As concentrations, highly influenced by lithology-mineralogy, soils-geomorphology, actual climate and paleoclimates, hydraulic parameters, and residence time of groundwaters.
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