| 1. |
- Bundschuh, Jochen, et al.
(författare)
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Arsenic in the human food chain : the Latin American perspective
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 92-106
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Forskningsöversikt (refereegranskat)abstract
- Many regions of Latin America are widely reported for the occurrence of high arsenic (As) in groundwater and surface water due to a combination of geological processes and/or anthropogenic activities. In this paper, we review the available literature (both in English and Spanish languages) to delineate human As exposure pathways through the food chain. Numerous studies show that As accumulations in edible plants and crops are mainly associated with the presence of high As in soils and irrigation waters. However, factors such as As speciation, type and composition of soil, and plant species have a major control on the amount of As uptake. Areas of high As concentrations in surface water and groundwater show high As accumulations in plants, fish/shellfish, livestock meat, milk and cheese. Such elevated As concentrations in food may result in widespread health risks to local inhabitants, including health of indigenous populations and residents living close to mining industries. Some studies show that As can be transferred from the water to prepared meals, thereby magnifying the As content in the human diet. Arsenic speciation might also change during food preparation, especially during high temperature cooking, such as grilling and frying. Finally, the review of the available literature demonstrates the necessity of more rigorous studies in evaluating pathways of As exposure through the human food chain in Latin America.
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| 2. |
- Bundschuh, Jochen, et al.
(författare)
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Emerging mitigation needs and sustainable options for solving the arsenic problems of rural and isolated urban areas in Latin America : A critical analysis
- 2010
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Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 44:19, s. 5828-5845
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Tidskriftsartikel (refereegranskat)abstract
- In this work, current information about the contamination of ground- and surface-water resources by arsenic from geogenic sources in Latin America is presented together with possible emerging mitigation solutions. The problem is of the same order of magnitude as other world regions, such as SE Asia, but it is often not described in English. Despite the studies undertaken by numerous local researchers, and the identification of proven treatment methods for the specific water conditions encountered, no technologies have been commercialized due to a current lack of funding and technical assistance. Emerging, low-cost technologies to mitigate the problem of arsenic in drinking water resources that are suitable for rural and urban areas lacking centralized water supplies have been evaluated. The technologies generally use simple and low-cost equipment that can easily be handled and maintained by the local population. Experiences comprise (i) coagulation/filtration with iron and aluminum salts, scaled-down for small community-and household-scale-applications, (ii) adsorption techniques using low-cost arsenic sorbents, such as geological materials (clays, laterites, soils, limestones), natural organic-based sorbents (natural biomass), and synthetic materials. TiO2-heterogeneous photocatalysis and zerovalent iron, especially using nanoscale particles, appear to be promising emergent technologies. Another promising innovative method for rural communities is the use of constructed wetlands using native perennial plants for arsenic rhizofiltration. Smallscale simple reverse osmosis equipment (which can be powered by wind or solar energy) that is suitable for small communities can also be utilized. The individual benefits of the different methods have been evaluated in terms of (i) size of the treatment device, (ii) arsenic concentration and distribution of species, chemical composition and grade of mineralization in the raw water, (iii) guidelines for the remaining As concentration, (iv) economical constrains, (v) complexity of installation and maintenance, and infrastructure constraints (e.g. electricity needs). (c) 2010 Elsevier Ltd. All rights reserved.
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| 3. |
- 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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| 4. |
- Householder, John Ethan, et al.
(författare)
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One sixth of Amazonian tree diversity is dependent on river floodplains
- 2024
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Ingår i: NATURE ECOLOGY & EVOLUTION. - 2397-334X. ; 8, s. 901-911
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Tidskriftsartikel (refereegranskat)abstract
- Amazonia's floodplain system is the largest and most biodiverse on Earth. Although forests are crucial to the ecological integrity of floodplains, our understanding of their species composition and how this may differ from surrounding forest types is still far too limited, particularly as changing inundation regimes begin to reshape floodplain tree communities and the critical ecosystem functions they underpin. Here we address this gap by taking a spatially explicit look at Amazonia-wide patterns of tree-species turnover and ecological specialization of the region's floodplain forests. We show that the majority of Amazonian tree species can inhabit floodplains, and about a sixth of Amazonian tree diversity is ecologically specialized on floodplains. The degree of specialization in floodplain communities is driven by regional flood patterns, with the most compositionally differentiated floodplain forests located centrally within the fluvial network and contingent on the most extraordinary flood magnitudes regionally. Our results provide a spatially explicit view of ecological specialization of floodplain forest communities and expose the need for whole-basin hydrological integrity to protect the Amazon's tree diversity and its function.
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| 5. |
- Lopez, Dina L., et al.
(författare)
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Arsenic in volcanic geothermal fluids of Latin America
- 2012
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 429, s. 57-75
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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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| 6. |
- Luize, Bruno Garcia, et al.
(författare)
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Geography and ecology shape the phylogenetic composition of Amazonian tree communities
- 2024
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Ingår i: JOURNAL OF BIOGEOGRAPHY. - 0305-0270 .- 1365-2699. ; 51:7, s. 1163-1184
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Amazonia hosts more tree species from numerous evolutionary lineages, both young and ancient, than any other biogeographic region. Previous studies have shown that tree lineages colonized multiple edaphic environments and dispersed widely across Amazonia, leading to a hypothesis, which we test, that lineages should not be strongly associated with either geographic regions or edaphic forest types. Location: Amazonia. Taxon: Angiosperms (Magnoliids; Monocots; Eudicots). Methods: Data for the abundance of 5082 tree species in 1989 plots were combined with a mega-phylogeny. We applied evolutionary ordination to assess how phylogenetic composition varies across Amazonia. We used variation partitioning and Moran's eigenvector maps (MEM) to test and quantify the separate and joint contributions of spatial and environmental variables to explain the phylogenetic composition of plots. We tested the indicator value of lineages for geographic regions and edaphic forest types and mapped associations onto the phylogeny. Results: In the terra firme and v & aacute;rzea forest types, the phylogenetic composition varies by geographic region, but the igap & oacute; and white-sand forest types retain a unique evolutionary signature regardless of region. Overall, we find that soil chemistry, climate and topography explain 24% of the variation in phylogenetic composition, with 79% of that variation being spatially structured (R-2 = 19% overall for combined spatial/environmental effects). The phylogenetic composition also shows substantial spatial patterns not related to the environmental variables we quantified (R-2 = 28%). A greater number of lineages were significant indicators of geographic regions than forest types. Main Conclusion: Numerous tree lineages, including some ancient ones (>66 Ma), show strong associations with geographic regions and edaphic forest types of Amazonia. This shows that specialization in specific edaphic environments has played a long-standing role in the evolutionary assembly of Amazonian forests. Furthermore, many lineages, even those that have dispersed across Amazonia, dominate within a specific region, likely because of phylogenetically conserved niches for environmental conditions that are prevalent within regions.
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| 7. |
- ter Steege, Hans, et al.
(författare)
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Mapping density, diversity and species-richness of the Amazon tree flora
- 2023
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Ingår i: COMMUNICATIONS BIOLOGY. - 2399-3642. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution. A study mapping the tree species richness in Amazonian forests shows that soil type exerts a strong effect on species richness, probably caused by the areas of these forest types. Cumulative water deficit, tree density and temperature seasonality affect species richness at a regional scale.
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