Arsenic and Selenium

Plant, Jane A.; Kinniburgh, D.G.; Smedley, Pauline; Fordyce, F.M.; Klinck, Ben

doi:10.1016/b0-08-043751-6/09047-2

Cited by 116 publications

(149 citation statements)

References 201 publications

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“…These results are probably due to the difference on water chemistry; the Se-rich VF effluents are characterized by a neutral to high (6−8) pH, while the water-soluble leachates from the laboratory experiments were much more acidic ( Table 1). Given that selenium mobilization is expected to intensify under elevated pH conditions, 39 we posit that the generation of sulfuric acid from pyrite oxidation would trigger carbonate dissolution, which would buffer the pH of VF effluents and further enhance selenium mobilization from the carbonate phases. We conclude that the geochemical and isotopic changes we observed in leachates from rocks spanning the transition from Allegheny to Kanawha Formations are representative of the expected composition of the blended rock found in VFs and the resulting chemical influence they have on the headwaters flowing to the Mud River.…”

Section: Environmental Science and Technologymentioning

confidence: 99%

Isotopic Imprints of Mountaintop Mining Contaminants

Vengosh

Lindberg

Merola

et al. 2013

Environ. Sci. Technol.

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Mountaintop mining (MTM) is the primary procedure for surface coal exploration within the central Appalachian region of the eastern United States, and it is known to contaminate streams in local watersheds. In this study, we measured the chemical and isotopic compositions of water samples from MTM-impacted tributaries and streams in the Mud River watershed in West Virginia. We systematically document the isotopic compositions of three major constituents: sulfur isotopes in sulfate (δ 34 S SO4 ), carbon isotopes in dissolved inorganic carbon (δ 13 C DIC ), and strontium isotopes ( 87 Sr/ 86 Sr). The data show that δ 34 S SO4 , δ 13 C DIC , Sr/Ca, and 87 Sr/ 86 Sr measured in saline-and selenium-rich MTM impacted tributaries are distinguishable from those of the surface water upstream of mining impacts. These tracers can therefore be used to delineate and quantify the impact of MTM in watersheds. High Sr/Ca and low 87 Sr/ 86 Sr characterize tributaries that originated from active MTM areas, while tributaries from reclaimed MTM areas had low Sr/Ca and high 87 Sr/ 86 Sr. Leaching experiments of rocks from the watershed show that pyrite oxidation and carbonate dissolution control the solute chemistry with distinct 87 Sr/ 86 Sr ratios characterizing different rock sources. We propose that MTM operations that access the deeper Kanawha Formation generate residual mined rocks in valley fills from which effluents with distinctive 87 Sr/ 86 Sr and Sr/Ca imprints affect the quality of the Appalachian watersheds.

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Section: Environmental Science and Technologymentioning

confidence: 99%

Isotopic Imprints of Mountaintop Mining Contaminants

Vengosh

Lindberg

Merola

et al. 2013

Environ. Sci. Technol.

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“…Although Se concentrations varied greatly between the two morphologies or within the same morphological type in a single sample, overall Se concentrations tended to be higher in euhedral grains (Table 2 and Table S8 in the SI). Because of the close link between shale pyrite weathering and Se release, 8,12,22,23,29 hereafter we focused our Se μ-XAS analyses solely on samples UK-1 and UK-2. These represent typical shales containing pyrite and organic matter (Table S6 in the SI) and the highest bulk Se concentrations among the samples studied.…”

Section: Bulk Composition and Se Distribution In The Variousmentioning

confidence: 99%

“…15 However, neither the importance of OM as a Se host, nor a clear correlation between Se and OM in typical black shales, with average lower Se concentrations, have so far been demonstrated. Conversely, several studies proposed pyrite as the possible Se host mineral in shales, 5,8,16,17 yet a mechanistic or speciation related explanation is still lacking. Experimental studies 18−21 suggested that Se is likely either adsorbed/reduced on preformed pyrite grains or structurally incorporated into the sulfide phase.…”

Section: ■ Introductionmentioning

confidence: 99%

“…5,9,10 In Se-enriched surface environments, shales are an important source of Se to soils. 5,8,11,12 However, the transfer of Se from shale rocks into soils and groundwaters 5 and ultimately to humans via the food chain 6 is poorly constrained. Furthermore, the role of geological settings or specific geochemical reactions leading to the sequestration of Se in shale components are also poorly understood.…”

Section: ■ Introductionmentioning

confidence: 99%

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Selenium Speciation in Framboidal and Euhedral Pyrites in Shales

Matamoros-Veloza

Peacock

Benning

2014

Environ. Sci. Technol.

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The release of Se from shales is poorly understood because its occurrence, distribution, and speciation in the various components of shale are unknown. To address this gap we combined bulk characterization, sequential extractions, and spatially resolved μ-focus spectroscopic analyses and investigated the occurrence and distribution of Se and other associated elements (Fe, As, Cr, Ni, and Zn) and determined the Se speciation at the μ-scale in typical, low bulk Se containing shales. Our results revealed Se primarily correlated with the pyrite fraction with exact Se speciation highly dependent on pyrite morphology. In euhedral pyrites, we found Se(-II) substitutes for S in the mineral structure.However, we also demonstrate that Se is associated with framboidal pyrite grains as a discrete, independent FeSe x phase. The presence of this FeSe x species has major implications for Se release, because FeSe x species oxidize much faster than Se substituted in the euhedral pyrite lattice. Thus, such an FeSe x species will enhance and control the dynamics of Se weathering and release into the aqueous environment.

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“…The most common sources of arsenic in the natural environment are volcanic rocks (specifically their weathering products and ash), marine sedimentary rocks, hydrothermal ore deposits and associated geothermal waters, and fossil fuels, including coals and petroleum (Wang and Mulligan 2006;Smedley and Kinniburgh 2002). Anthropogenic activity, such as gold mining, has contributed to a sharp rise in natural arsenic concentrations reported for many artesian water supplies, often exceeding 600 μg l -1 As (Duker et al 2005;Farias et al 2003;Plant et al 2003). Local communities use these water supplies for drinking, cooking (Tseng 2009;Roychowdhury et al 2005), cattle watering (Nriagu et al 2007) and crop irrigation Hossain 2006;Bundschuh et al 2004), creating a possible pathway for the arsenic to enter both the animal and human populations.…”

Section: Introductionmentioning

confidence: 99%

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina

O'Reilly

Watts

Shaw

et al. 2010

Environ Geochem Health

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Arsenic (As) speciation in surface and groundwater from two provinces in Argentina (San Juan and La Pampa) was investigated using solid phase extraction (SPE) cartridge methodology with comparison to total arsenic concentrations. A third province, Río Negro, was used as a control to the study. Strong cation exchange (SCX) and strong anion exchange (SAX) cartridges were utilised in series for the separation and preservation of arsenite (As ). Samples were collected from a range of water outlets (rivers/streams, wells, untreated domestic taps, well water treatment works) to assess the relationship between total arsenic and arsenic species, water type and water parameters (pH, conductivity and total dissolved solids, TDS). Analysis of the waters for arsenic (total and species) was performed by inductively coupled plasma mass spectrometry (ICP-MS) in collision cell mode. Total arsenic concentrations in the surface and groundwater from Encon and the San José de Jáchal region of San Juan (north-west Argentina within the Cuyo region) ranged from 9 -357 μg l -1As. Groundwater from Eduardo Castex (EC) and Ingeniero Luiggi (LU) in La Pampa (central Argentina within the Chaco-Pampean Plain) ranged from 3 -1326 μg l -1As. The pH range for the provinces of San Juan (7.2 -9.7) and La Pampa (7.0 -9.9) are in agreement with other published literature. The highest total arsenic concentrations were found in La Pampa well waters (both rural farms and pre-treated urban sources), particularly where there was high pH (typically > 8.2), conductivity (> 2600 μS cm As. Arsenic species for both provinces were predominantly As for groundwater, respectively. This translates to a relative As III abundance of 69 -100 % of the total arsenic in surface waters and 32 -100 % in groundwater. This is unexpected because it is typically thought that in oxidising conditions (surface waters), the dominant arsenic species is As V . However, data from the SPE methodology suggests that As III is the prevalent species in San Juan, indicating a greater influence from reductive processes. La Pampa groundwater had As (equating to up to 33 % of the total arsenic). Previously published literature has focused primarily on the inorganic arsenic species, however this study highlights the potentially significant concentrations of organoarsenicals present in natural waters. The potential for separating and preserving individual arsenic species in the field to avoid transformation during transport to the laboratory, enabling an accurate assessment of in-situ arsenic speciation in water supplies is discussed.

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Arsenic and Selenium

Cited by 116 publications

References 201 publications

Isotopic Imprints of Mountaintop Mining Contaminants

Isotopic Imprints of Mountaintop Mining Contaminants

Selenium Speciation in Framboidal and Euhedral Pyrites in Shales

Arsenic contamination of natural waters in San Juan and La Pampa, Argentina

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