| 1. |
- Ramos, Oswaldo Eduardo, et al.
(author)
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Arsenic fractionation in soils in mining region of the Bolivian Altiplano
- 2012
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In: Understanding the Geological and Medical Interface of Arsenic, As 2012 - 4th International Congress: Arsenic in the Environment. - : Taylor & Francis Group. - 9780415637633 ; , s. 335-336
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Conference paper (peer-reviewed)abstract
- Cultivated soils in mining areas are degraded by natural and anthropogenic processes. A sequential extraction procedure in soils was conducted to fractionate the arsenic (As) content along a transect with active agriculture. The distribution of As in soil showed a small percentage on the exchangeable fraction, while a major As pool could be released depending on the crop and soil management.
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| 2. |
- Ramos Ramos, O. E., et al.
(author)
-
Geochemical processes controlling mobilization of arsenic and Trace Elements in shallow aquifers in mining regions, Bolivian Altiplano
- 2014
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In: One Century of the Discovery of Arsenicosis in Latin America (1914-2014). - : CRC Press. - 9781138001411 ; , s. 239-241
-
Conference paper (peer-reviewed)abstract
- A geochemical approach was applied to understand the factors controlling the mobilization of As and trace elements (TEs) in these mining areas. A total of 30 samples (wells and geothermal water) were collected during the rainy season (2009). As, Cd and Mn concentrations exceed WHO drinking guidelines in some groundwater samples, but Cu, Ni, Pb and Zn do not. Factor analysis of the groundwater chemical data suggests the following geochemical processes: i) plagioclase weathering, ii) dissolution of gypsum and halite, iii) trace element mobilization at acidic pH, iv) sulfide oxidation, and v) release of As following competition with phosphate and bicarbonate for adsorption sites. The As and TEs mobilized in these regions could affect the local water sources, which is a prevalent concern with respect to water resource management in this semi-arid Altiplano region.
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| 3. |
- Ramos Ramos, Oswaldo Eduardo, et al.
(author)
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Sources and behavior of arsenic and trace elements in groundwater and surface water in the Poopó Lake Basin, Bolivian Altiplano
- 2012
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In: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 66:3, s. 793-807
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Journal article (peer-reviewed)abstract
- Water management in semiarid and arid catchments such as the Poopó Lake Basin requires improved understanding of the complex behavior of the various contaminants, which affect the drinking water quality and considered as crucial for sustainable development of the region. Mechanisms of arsenic (As) release in the surface and groundwater were studied. Hydrochemical data for surface water (4 samples) and groundwater (28 samples) were collected in a small watershed in the Poopó catchment at the highland of the Bolivian Andes (Altiplano). All of them show high electrical conductivity values and moderately oxidizing conditions. The surface water contains high concentration of sulfate and the trace elements As, Zn and Pb in the zone affected by acid mine drainage. There is a large variability of the concentration of As and of the trace elements in the groundwater in the five different regions within the Poopó catchment. The metal concentrations sensitive to changes of redox state and results of speciation modeling suggest that As (V) is a predominant aqueous species, which conforms to the prevailing oxidizing conditions in the shallow groundwater environment. Two generalized trends for As distribution were identified in groundwater: (a) high concentrations are found in the arid zone (100-250 Όg/L) in the southern (region III) and in the northwestern (region V) regions, and (b) low concentrations (< 50 Όg/L) are found in the remaining part of the basin (region I, II and IV). However, the spatial distribution within these regions needs to be investigated further. A conclusion from the present study is that there are multiple sources of As as well as other trace elements (such as Cd, Mn and Zn) in the Poopó Lake Basin. Among the sources and the processes which led to the mobility of As and other trace metals in the region are: (a) weathering of sulfide minerals, (b) oxidation of pyrite and/or arsenopyrite in mineralized areas and (c) desorption from hydrous ferric oxide (HFO) surfaces. In non-mining areas, volcanic ash is suggested to be a significant source of As.
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