Dissolved Organic Matter Quality in a Shallow Aquifer of Bangladesh: Implications for Arsenic Mobility

Mladenov, Natalie; Zheng, Yan; Simone, Bailey; Bilinski, Theresa M.; McKnight, Diane M.; Nemergut, Diana R.; Radloff, K. A.; Rahman, Mohammad Moshiur; Ahmed, Kazi Matin

doi:10.1021/acs.est.5b01962

Cited by 150 publications

(70 citation statements)

References 69 publications

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“…The common theme underlying these and many other studies is the extent to which the release of As to groundwater in Holocene aquifers is regulated by the availability of reactive carbon and/or exchangeable As (Harvey et al 2002; Zheng et al, 2005; Mladenov et al 2015). For both reactive carbon and exchangeable As, either transport from a shallow source that affects a shallow aquifer or in situ reaction from sediment within the aquifer has been invoked for different sites (Polizzotto et al, 2008; Neumann et al, 2010; Desbarats et al, 2014; Harvey et al, 2006; Mladenov et al, 2009; Mailloux et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Reversible adsorption and flushing of arsenic in a shallow, Holocene aquifer of Bangladesh

Radloff

Zheng

Stute

et al. 2017

Applied Geochemistry

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The spatial heterogeneity of dissolved arsenic (As) concentrations in shallow groundwater of the Bengal Basin has been attributed to transport of As (and reactive carbon) from external sources or to the release of As from within grey sand formations. We explore the latter scenario in this detailed hydrological and geochemical study along a 300 m transect of a shallow aquifer extending from a groundwater recharge area within a sandy channel bar to its discharge into a nearby stream. Within the 10–20 m depth range, groundwater ages along the transect determined by the 3H–3He method increase from <10 yr in the recharge area to a maximum of 40 yr towards the stream. Concentrations of groundwater As within the same grey sands increase from 10 to 100 to ∼500 µg/L along this transect. Evidence of reversible adsorption of As between the groundwater and sediment was obtained from a series of push–pull experiments, traditional batch adsorption experiments, and the accidental flooding of a shallow monitoring well. Assuming reversible adsorption and a distribution coefficient, Kd, of 0.15–1.5 L/kg inferred from these observations, a simple flushing model shows that the increase in As concentrations with depth and groundwater age at this site, and at other sites in the Bengal and Red River Basins, can be attributed to the evolution of the aquifer over 100–1000 years as aquifer sands are gradually flushed of their initial As content. A wide range of As concentrations can thus be maintained in groundwater with increases with depth governed by the history of flushing and local recharge rates, without external inputs of reactive carbon or As from other sources.

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Section: Introductionmentioning

confidence: 99%

Reversible adsorption and flushing of arsenic in a shallow, Holocene aquifer of Bangladesh

Radloff

Zheng

Stute

et al. 2017

Applied Geochemistry

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“…Additionally, the gain and loss of DOC in the liquid phase resulting from microbial assimilation of the exogenous and endogenous organics were explained in Figure S3. Without acetate supplement, the bioavailability of DOC just reflected the terrestrial leaching of DOM (Figure a), because the microbial physiological metabolism only relied on the assimilation of indigenous labile organics (Mladenov et al, ). Because the sedimentary DOM in soil is usually recalcitrant, acetate serving as a low‐molecular‐weight organic carbon compound is generally preferentially utilized as the primary carbon source for supporting indigenous microbial growth and energy conservation (M. Chen & Hur, ).…”

Section: Resultsmentioning

confidence: 99%

“…Additionally, the gain and loss of DOC in the liquid phase resulting from microbial assimilation of the exogenous and endogenous organics were explained in Figure S3. Without acetate supplement, the bioavailability of DOC just reflected the terrestrial leaching of DOM (Figure 3a), because the microbial physiological metabolism only relied on the assimilation of indigenous labile organics (Mladenov et al, 2015). Additionally, fluorescence regional integration analysis showed that both the LDOM level and the SDOM level derived from the graphenebased amendments remained lower than the levels from the amendments that lacked graphene (Figure 3g,h).…”

Section: Bioavailability Of Dommentioning

confidence: 99%

Addition of graphene sheets enhances reductive dissolution of arsenic and iron from arsenic contaminated soil

Chen

et al. 2018

Land Degrad Dev

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The deposition of slag from a realgar tailing mine has caused serious land degradation to those farming and mining coexisting areas. However, nanomaterial‐mediated biogeochemical arsenic cycle from arsenic‐enriched soil was severely limited. In this study, the environmental impact of graphene oxide (GO) and reduced GO (rGO) on the speciation and mobilization of Fe/As from the flooding of arsenic‐enriched soil was investigated. Regarding overall performance, rGO exhibited a more significant facilitation than GO on mediating microbial reduction of Fe(III)/As(V). The maximal levels of soluble Fe(II) and As(III) in the soil supplemented with acetate alone were 53.58 g.m−3 and 9592 mg·m−3 during the 50‐day culture period. Nearly 1.37‐fold and 1.15‐fold of As(III) levels were released when amending with rGO acetate and GO acetate. Meanwhile, approximately 1.40‐fold and 1.24‐fold of Fe(II) levels were released under the same conditions. The underlying mechanism was correlated with the interactions between graphene and microbial activities. The properties of GO have been evolved through microbial reduction and eventually exhibited characteristics similar to rGO. Additionally, the application of graphene potentially altered the compositions of the microbial community and increased the abundance of some metal‐reducing bacteria (e.g., Bacillus, Geobacter, and Desulfitobacterium), thereby favouring the dissolved organic matter bioavailability for bioreduction of Fe(III)/As(V). In addition, promotion of the electron transfer process of As(V)/Fe(III) reduction was predominantly responsible for the crucial role that rGO exhibited as a special redox‐active mediator and electrical conductor. These findings might provoke more consideration of the integrated ecological effects of graphene and evaluate their environmental impact on land degradation.

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“…3,18,21,22 As suas características e reatividade são dependentes da sua origem, o que também vai afetar o comportamento de metais-traços em meio aquático. 23,24 As SH são conhecidas por formar homoagregados (agregação com mesmo tipo de coloide) ou heteroagregados (agregados com mais de um tipo de coloide), levando à formação de diferentes formas físico-químicas dos coloides, nas quais metais e metaloides podem interagir. 3 As SH podem, por exemplo, manter oxi-hidróxidos de Fe em solução, influenciando sua mobilidade no ambiente.…”

Section: Metais E Metaloides Em Ambientes Aquáticosunclassified

Metal and Metalloid Speciation in Aquatic Environments: Concepts, Techniques and Applications

Gontijo¹,

Monteiro²,

Rosa³

2017

Rev. Virtual Quim.

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Aquatic environments are dynamic systems, where metals and metalloids are continuously transformed and mobilised through different chemical forms among organic and inorganic substances and particulate material. These different forms of an element have different behaviours in a way that its total concentration provides just incomplete information related to mobility, bioavailability and toxicity. This work aimed to show the main features of the behaviour of metals and metalloids in aquatic environments and present the main techniques used in the investigation of chemical species and/or interactions with colloids and particulate material. Some of these techniques include filtration, ultrafiltration (UF), diffusive gradients in thin films (DGT), scanned deposition potential (SCP) and absence of gradients and nernstian equilibrium stripping (AGNES). Speciation and fractioning studies of water samples can indicate the potential bioavailability and mobility of metals and metalloids, especially when different techniques are used together.Keywords: Ultrafiltration; DGT; electrochemical techniques; trace metals; organic ligands. ResumoAmbientes aquáticos são sistemas dinâmicos, onde metais e metaloides transformam-se constantemente e são mobilizados em diferentes formas químicas na presença de substâncias orgânicas, inorgânicas e material particulado. Essas diferentes formas de um dado elemento possuem diversos comportamentos no ambiente, de modo que apenas a análise da sua concentração total fornece informações incompletas relativas a mobilidade, biodisponibilidade e toxicidade. Este trabalho teve como objetivos mostrar os principais aspectos do comportamento de metais e metaloides no meio aquático e apresentar algumas das principais técnicas utilizadas para estudo das suas espécies químicas e/ou interações com coloides e material particulado. Algumas dessas técnicas incluem filtração, ultrafiltração, difusão em filmes finos por gradientes de concentração (DGT), cronopotenciometria de redissolução anódica (SCP) e redissolução nernstiana na ausência de gradientes (AGNES). Estudos de especiação e fracionamento de amostras de água podem indicar a potencial biodisponibilidade e mobilidade de metais e metaloides, especialmente quando diferentes técnicas são aplicadas em conjunto.Palavras-chave: Ultrafiltração; DGT; técnicas eletroquímicas; metais-traço; ligantes orgânicos.

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Dissolved Organic Matter Quality in a Shallow Aquifer of Bangladesh: Implications for Arsenic Mobility

Cited by 150 publications

References 69 publications

Reversible adsorption and flushing of arsenic in a shallow, Holocene aquifer of Bangladesh

Reversible adsorption and flushing of arsenic in a shallow, Holocene aquifer of Bangladesh

Addition of graphene sheets enhances reductive dissolution of arsenic and iron from arsenic contaminated soil

Metal and Metalloid Speciation in Aquatic Environments: Concepts, Techniques and Applications

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