Arsenic release metabolically limited to permanently water-saturated soil in Mekong Delta

Stuckey, Jason W.; Schaefer, Michael V.; Kocar, Benjamin D.; Benner, S. G.; Fendorf, Scott

doi:10.1038/ngeo2589

Cited by 155 publications

(112 citation statements)

References 40 publications

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“…14,40 However, this observation would also be consistent with As release occurring close to recharge points and being transported with water as has been suggested recently. 39 The approaches used within this research study are unable to differentiate between these two possibilities and thus warrants future research.…”

Section: Discussionmentioning

confidence: 96%

Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids

Whaley-Martin

Mailloux

Geen

et al. 2016

Environ. Sci. Technol.

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The sources of reduced carbon driving the microbially mediated release of arsenic to shallow groundwater in Bangladesh remain poorly understood. Using radiocarbon analysis of phospholipid fatty acids (PLFAs) and potential carbon pools, the abundance and carbon sources of the active, sediment-associated, in situ bacterial communities inhabiting shallow aquifers (<30 m) at two sites in Araihazar, Bangladesh, were investigated. At both sites, sedimentary organic carbon (SOC) Δ14C signatures of −631 ± 54‰ (n = 12) were significantly depleted relative to dissolved inorganic carbon (DIC) of +24 ± 30‰ and dissolved organic carbon (DOC) of −230 ± 100‰. Sediment-associated PLFA Δ14C signatures (n = 10) at Site F (−167‰ to +20‰) and Site B (−163‰ to +21‰) were highly consistent and indicated utilization of carbon sources younger than the SOC, likely from the DOC pool. Sediment-associated PLFA Δ14C signatures were consistent with previously determined Δ14C signatures of microbial DNA sampled from groundwater at Site F indicating that the carbon source for these two components of the subsurface microbial community is consistent and is temporally stable over the two years between studies. These results demonstrate that the utilization of relatively young carbon sources by the subsurface microbial community occurs at sites with varying hydrology. Further they indicate that these young carbon sources drive the metabolism of the more abundant sediment-associated microbial communities that are presumably more capable of Fe reduction and associated release of As. This implies that an introduction of younger carbon to as of yet unaffected sediments (such as those comprising the deeper Pleistocene aquifer) could stimulate microbial communities and result in arsenic release.

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Section: Discussionmentioning

confidence: 96%

Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids

Whaley-Martin

Mailloux

Geen

et al. 2016

Environ. Sci. Technol.

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“…Connectivity between surface landforms and the facies architecture of the subsurface deposits, may affect the bioavailability of sedimentary OC to the microbial community and thus potentially impact arsenic release 11–21 . For example, sandy windows within clay caps may allow a potential pathway for young surface derived OC to penetrate the aquifer to depth 22,23 .…”

Section: Introductionmentioning

confidence: 99%

Biomarker-indicated extent of oxidation of plant-derived organic carbon (OC) in relation to geomorphology in an arsenic contaminated Holocene aquifer, Cambodia

Magnone

Richards

Polya

et al. 2017

Sci Rep

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The poisoning of rural populations in South and Southeast Asia due to high groundwater arsenic concentrations is one of the world’s largest ongoing natural disasters. It is important to consider environmental processes related to the release of geogenic arsenic, including geomorphological and organic geochemical processes. Arsenic is released from sediments when iron-oxide minerals, onto which arsenic is adsorbed or incorporated, react with organic carbon (OC) and the OC is oxidised. In this study we build a new geomorphological framework for Kandal Province, a highly studied arsenic affected region of Cambodia, and tie this into wider regional environmental change throughout the Holocene. Analyses shows that the concentration of OC in the sediments is strongly inversely correlated to grainsize. Furthermore, the type of OC is also related to grain size with the clay containing mostly (immature) plant derived OC and sand containing mostly thermally mature derived OC. Finally, analyses indicate that within the plant derived OC relative oxidation is strongly grouped by stratigraphy with the older bound OC more oxidised than younger OC.

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“…Bangladesh aquifer sediments are oligotrophic containing low carbon and inputs of labile carbon sources has been shown experimentally (Dhar et al, 2011; Islam et al, 2004; Stuckey et al, 2015) to stimulate the in situ sedimentary bacterial communities and ultimately arsenic release. Islam et al (2004) detected a major shift in the sediment associated community with iron-reducing ( Geobacter ) bacteria increases when a small amounts of carbon (acetate) was added to Bangladesh sediments in a microcosm experiment.…”

Section: Discussionmentioning

confidence: 99%

“…A number of potential sources of organic carbon including human waste (Harvey et al, 2002; McArthur et al, 2012), man-made constructed ponds (Lawson et al, 2013; Neumann et al, 2010), wetland/rice paddy environments (Meharg et al, 2006; Polizzotto et al, 2008; Stuckey et al, 2015), river-derived flows (van Geen et al, 2013), buried peat layers (Anawar et al, 2003; McArthur et al, 2004, 2001; Mladenov et al, 2010; Planer-Friedrich et al, 2012; Ravenscroft et al, 2001; Yamazaki et al, 2003) and organics deposited with sediments (Desbarats et al, 2014; Meharg et al, 2006; Nickson et al, 2000; Postma et al, 2012, 2007) have been proposed based on studies conducted at various sites. Recent evidence based on Δ 14 C analysis of microbial lipids, DNA and biogenic methane from a few sites in Bangladesh has indicated that reductive dissolution of iron (Fe) oxides at depths <30 m may be driven primarily by relatively young surface-derived carbon sources as opposed to older sedimentary carbon (Harvey et al, 2002; Mailloux et al, 2013; Whaley-Martin et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…In a recent field experiment, Stuckey et al (2015) stimulated Fe reduction and As release from Cambodian sediments by adding large quantities of local grass as a microbial carbon source. In contrast, Neumann et al (2014) found dissolved organic carbon (DOC) carried from rice-paddy fields (plant-derived) shows limited biological degradation under natural conditions and instead proposed DOC carried with recharge water from ponds as a predominant microbial carbon source at one site.…”

Section: Introductionmentioning

confidence: 99%

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Human and livestock waste as a reduced carbon source contributing to the release of arsenic to shallow Bangladesh groundwater

Whaley-Martin

Mailloux

Geen

et al. 2017

Science of The Total Environment

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Recent studies have demonstrated that the supply of relatively young organic carbon stimulates the release of arsenic to groundwater in Bangladesh. This study explores the potential role of human and livestock waste as a significant source of this carbon in a densely populated rural area with limited sanitation. Profiles of aquifer sediment samples were analyzed for phytosterols and coprostanol to assess the relative contributions of plant-derived and human/livestock waste-derived organic carbon at two well-characterized sites in Araihazar. Coprostanol concentrations increased with depth from non-detection (<10 m at Site B and <23 m at Site F) to maxima of 1.3 and 0.5 ng/g in aquifer sands recovered from 17 m (Site B) and 26 m (Site F), respectively. The commonly used sewage contamination index ([5β-coprostanol]/([5α-cholestanol] + [5β-coprostanol])) exceeds 0.7 between 12 and 19 m at Site B and between 24 and 26 m at Site F, indicating input of human/livestock waste to these depths. Urine/fecal input within the same depth range is supported by groundwater Cl/Br mass ratios >1000 compared to Cl/Br <500 at depths >50 m. Installed tube wells in the area’s study sites may act as a conduit for DOC and specifically human/livestock waste into the aquifer during flood events. The depth range of maximum input of human/livestock waste indicated by these independent markers coincides with the highest dissolved Fe (10–20 mg/L) and As (200–400 μg/L) concentrations in groundwater at both sites. The new findings suggest that the oxidation of human/livestock waste coupled to the reductive dissolution of iron-(oxy)-hydroxides and/or arsenate may enhance groundwater contamination with As.

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Arsenic release metabolically limited to permanently water-saturated soil in Mekong Delta

Cited by 155 publications

References 40 publications

Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids

Stimulation of Microbially Mediated Arsenic Release in Bangladesh Aquifers by Young Carbon Indicated by Radiocarbon Analysis of Sedimentary Bacterial Lipids

Biomarker-indicated extent of oxidation of plant-derived organic carbon (OC) in relation to geomorphology in an arsenic contaminated Holocene aquifer, Cambodia

Human and livestock waste as a reduced carbon source contributing to the release of arsenic to shallow Bangladesh groundwater

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