| 1. |
- Caceres Choque, Luis Fernando, et al.
(författare)
-
Fractionation of heavy metals and assessment of contamination of the sediments of Lake Titicaca
- 2013
-
Ingår i: Environmental Monitoring & Assessment. - : Springer Science and Business Media LLC. - 0167-6369 .- 1573-2959. ; 185:12, s. 9979-9994
-
Tidskriftsartikel (refereegranskat)abstract
- Chemical weathering is one of the major geochemical processes that control the mobilization of heavy metals. The present study provides the first report on heavy metal fractionation in sediments (8-156 m) of Lake Titicaca (3,820 m a.s.l.), which is shared by the Republic of Peru and the Plurinational State of Bolivia. Both contents of total Cu, Fe, Ni, Co, Mn, Cd, Pb, and Zn and also the fractionation of these heavy metals associated with four different fractions have been determined following the BCR scheme. The principal component analysis suggests that Co, Ni, and Cd can be attributed to natural sources related to the mineralized geological formations. Moreover, the sources of Cu, Fe, and Mn are effluents and wastes generated from mining activities, while Pb and Zn also suggest that their common source is associated to mining activities. According to the Risk Assessment Code, there is a moderate to high risk related to Zn, Pb, Cd, Mn, Co, and Ni mobilization and/or remobilization from the bottom sediment to the water column. Furthermore, the Geoaccumulation Index and the Enrichment Factor reveal that Zn, Pb, and Cd are enriched in the sediments. The results suggest that the effluents from various traditional mining waste sites in both countries are the main source of heavy metal contamination in the sediments of Lake Titicaca.
|
|
| 2. |
- Coomar, Poulomee, et al.
(författare)
-
Contrasting controls on hydrogeochemistry of arsenic-enriched groundwater in the homologous tectonic settings of Andean and Himalayan basin aquifers, Latin America and South Asia
- 2019
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 689, s. 1370-1387
-
Tidskriftsartikel (refereegranskat)abstract
- High groundwater arsenic (As) across the globe has been one of the most well researched environmental concerns during the last two decades. Consequently, a large scientific knowledge-base has been developed on As distributions from local to global scales. However, differences in bulk sediment As concentrations cannot account for the As concentration variability in groundwater. Instead, in general, only aquifers in sedimentary basins adjacent to mountain chains (orogenic foreland basins) along continental convergent tectonic margins are found to be As enriched. We illustrate this association by integrating observations from long-term studies of two of the largest orogenic systems (i.e., As sources) and the aquifers in their associated foreland basins (As sinks), which are located in opposite hemispheres and experience distinct differences in climate and land-use patterns. The Andean orogenic system of South America (AB), an active continental margin, is in principle a modern analogue of the Himalayan orogenic system associated with the Indus-Ganges-Brahmaputra river systems in South Asia (HB). In general, the differences in hydrogeochemistry between AB and HB groundwaters are conspicuous. Major-solute composition of the arid, oxic AB groundwater exhibits a mixed-ion hydrochemical facies dominated by Na-Ca-Cl-SO4-HCO3. Molar calculations and thermodynamic modeling show that although groundwater of AB is influenced by cation exchange, its hydrochemical evolution is predominated by feldspar dissolution and relationships with secondary clays. In contrast, humid, strongly reducing groundwater of HB is dominated by Ca-HCO3 facies, suggestive of calcite dissolution, along with some weathering of silicates (monosiallitization). This work demonstrates that although hydrogeochemical evolutionary trends may vary with local climate and lithology, the fundamental similarities in global tectonic settings can still lead to the elevated concentrations of groundwater As.
|
|
| 3. |
- Ramos Ramos, Oswaldo Eduardo, et al.
(författare)
-
Sources and behavior of arsenic and trace elements in groundwater and surface water in the Poopó Lake Basin, Bolivian Altiplano
- 2012
-
Ingår i: Environmental Earth Sciences. - : Springer Science and Business Media LLC. - 1866-6280 .- 1866-6299. ; 66:3, s. 793-807
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 4. |
|
|
| 5. |
- Ramos, Oswaldo E., et al.
(författare)
-
Bioaccessibility of arsenic and other selective trace elements in soils around the mining areas of Bolivian Altiplano
- 2013
-
Ingår i: 12th International Conference on the Biogeochemistry of Trace Elements (ICOBTE). ; , s. Abstract 0220 - 000167-
-
Konferensbidrag (refereegranskat)abstract
- The occurrence of trace elements (TEs) in the soils from sites of historic and present activities both open pit (extracted Au, Ag) and underground mines (Ag, Zn, Pb, Sn) mining in Bolivian Altiplano and their toxicity is one of the major environmental concerns. The aim of this study is to assess the levels of toxic trace elements such as As, Cd, Pb and Zn in the soil and their bioavailability in three sub-basins along selected transects. A combination of DTPA, and sequential extraction procedure was adapted for assessment the As content in different fraction in the soils. The results showed that TE´s were mobilized under low pH in upstream segment, thus could be considered an important factor controlling their chemical behavior in these soils. In the downstream segment of the three sub-basins, the TE enrichments were related to an increased proportion of clay contents through adsorption processes. The bioavailable fractions of the TE´s in soils indicated considerable variability for As (< 2%), Cd (<32%), Cu (<9%), Ni (<11%), Pb (<5%) and Zn (<10%). By using As sequential extraction procedure found that the less than 11% of the total As is easily mobilized in soils, they are associated to fraction related to nonspecifically (F1) and specifically sorbed (F2) fraction, which could predict a helpful tool for environmental risk assessment of these trace element contamination on Bolivian Altiplano. Enrichment factors (EF) in the soils were significantly high for As and Cd, moderate for Pb and Zn, and low for Cu, Fe, Mn and Ni contents of TE´s were high in all crops along the studied transects, and the distribution followed the trend Zn>Cu>Pb>As>Ni>Cd. The bio-concentration factor (BCF) for As, Pb and Zn were lower (< 0.5) in all crops which indicate a limited bioavailability of these TE´s, except Cd that showed high BCF values in the study area. The bioavailable TE’s might take up by the crops and finally threat human health as potential impacts.
|
|
