Reconstructing the sedimentation history of the Bengal Delta Plain by means of geochemical and stable isotopic data

Neidhardt, Harald; Biswas, Ashis; Freikowski, Dominik; Majumder, Santanu; Chatterjee, Debashis; Berner, Zsolt

doi:10.1016/j.apgeochem.2013.06.017

Cited by 27 publications

(21 citation statements)

References 46 publications

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“…46 Holocene sediment cores from a neighbouring district (ca. 75 km south-west of our study site) revealed As concentrations up to 12.6 mg/kg sediment, 53 where the Holocene sediments are overlain by a silty clay layer of overbank deposits forming the surface aquitard. 54 The primary aquifer, henceforth referred to as the deep aquifer, flows in the Pleistocene sediments and is located ca.…”

Section: Study Sitementioning

confidence: 88%

Investigating Fluorescent Organic-Matter Composition as a Key Predictor for Arsenic Mobility in Groundwater Aquifers

Schittich

Wünsch

Kulkarni

et al. 2018

Environ. Sci. Technol.

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Dissolved organic matter (DOM) is linked to the heterogeneous distribution of elevated arsenic (As) in groundwater used for drinking and irrigation purposes, but the relationship between DOM characteristics and arsenic mobility has yet to be fully understood. Here, DOM from groundwater sampled in the Bengal Basin region was characterized using both conventional bulk emission-excitation (EEM) spectroscopy and high-performance size exclusion chromatography coupled to spectroscopy (HPSEC-EEM). Notably, application of the novel HPSEC-EEM approach permitted the total fluorescence of individual samples to be independently resolved into its underlying components. This allowed the external validation of the bulk-sample fluorescence decomposition and offered insight into the molecular size distribution of fluorescent DOM. Molecular size distributions were similar for the UVA fluorescent (C 310 , C 340) as well as the three visible fluorescent (C 390 , C 440 C 500) components. There was a greater visible fluorescence in shallow aquifer samples (10-33 m) with high As (SH, up to 418µg/L) than in samples from the same depth with lower As (up to 40µg/L). This indicated a link between DOM quality and As mobility within the shallow aquifer. The deep aquifer samples (170-200 m) revealed DOM characteristics similar to SH samples but had low As concentrations (<4µg/L), signifying that the deep aquifer is potentially vulnerable to As contamination. These findings pave the way for a more comprehensive assessment of the susceptibility of drinking water aquifers, thereby supporting the management of groundwater resources.

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Section: Study Sitementioning

confidence: 88%

Investigating Fluorescent Organic-Matter Composition as a Key Predictor for Arsenic Mobility in Groundwater Aquifers

Schittich

Wünsch

Kulkarni

et al. 2018

Environ. Sci. Technol.

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“…Distinct geological settings on the east and west sides of the river Bhagirathi have been previously discussed in Datta et al (2011), Sankar (2013), Sankar et al (2014), and Kulkarni et al (2016). Briefly, the geology of the sites located east of the river Bhagirathi consists of young Holocene sediments (∼7,000 years before present), whereas Pleistocene sediments (12,300-48,600 years before present) occur to the west of the river (Acharya et al, 2000;Mukherjee et al, 2007;Neidhardt et al, 2013). The permeability of Holocene sands east of the river Bhagirathi is reported to be 40-60 m d −1 , whereas the permeability of the Pleistocene sediments to the west are reported to be slightly lower (i.e., 20-30 m d −1 ; Mukherjee et al, 2007).…”

Section: Study Sitementioning

confidence: 99%

Biogeochemical Controls on the Release and Accumulation of Mn and As in Shallow Aquifers, West Bengal, India

Vega

Kulkarni

Mladenov

et al. 2017

Front. Environ. Sci.

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HIGHLIGHTS • Manganese and arsenic concentrations are elevated in Murshidabad groundwater. • Manganese release appears to be independent of dissolved organic matter quality. • Mineral precipitation and dissolution reactions impact fate of manganese. • Arsenic concentrations are related to dissolved organic matter quantity and quality. The prevalence of manganese (Mn) in Southeast Asian drinking water has recently become a topic of discussion, particularly when concurrent with elevated arsenic (As). Although Mn groundwater geochemistry has been studied, the link between dissolved organic matter (DOM) quality and Mn release is less understood. This work evaluates characteristics of DOM, redox chemistry, and the distribution of Mn within Murshidabad, West Bengal, India. Shallow aquifer samples were analyzed for cations, anions, dissolved organic carbon, and DOM properties using 3-dimensional fluorescence excitation emission matrices followed by parallel factor modeling analyses. Two biogeochemical regimes are apparent, separated geographically by the river Bhagirathi. East of the river, where E h and nitrate (NO − 3) values are low, humic-like DOM coexists with high dissolved Mn, As, and Fe. West of the river, lower dissolved As and Fe concentrations are coupled with more protein-like DOM and higher NO − 3 and E h values. Dissolved Mn concentrations are elevated in both regions. Based on the distribution of available electron acceptors, it is hypothesized that groundwater east of the Bhagirathi, which is more reducing and enriched in dissolved Fe and Mn but depleted in NO − 3 , is chemically dominated by Mn(IV)/Fe(III) reduction processes. West of the river where NO − 3 is abundant yet dissolved Fe is absent, NO − 3 and Mn(IV) likely buffer redox conditions such that E h values are not sufficiently reducing to release Fe into the dissolved phase. The co-occurrence of humic-like Vega et al. Biogeochemical Controls of Mn and As in Shallow Aquifers DOM with dissolved As, Fe, and Mn in the more reducing aquifers may reflect complex formation between humic DOM and metals, as well as electron shuttling processes involving humic DOM, which may enhance metal(loid) release. Saturation indices of rhodochrosite (MnCO 3) suggest that precipitation is thermodynamically favorable in a greater proportion of the more reducing sites, however humic DOM-Mn complexes may be inhibiting MnCO 3 precipitation. Where dissolved arsenic concentrations are low, it is postulated that Mn(IV) reduction is oxidizing As(III) to As(V), increasing the potential for re-adsorption of As(V) onto relatively stable, un-reduced or newly precipitated Fe-oxides. Manganese release appears to be independent of DOM quality, as it persists in both humic and protein-like DOM environments.

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“…Arsenic (As) contamination in groundwater of alluvial aquifers worldwide creates serious problem in drinking water resources [ 1 – 4 ]. Among the contaminated sites, Bengal delta plain (BDP) that covers nearly 2 × 10 5 km 2 area of West Bengal (India) and Bangladesh, is the worst As affected geological province with more than 50 million people being under threat [ 4 – 6 ]. BDP is formed by the sedimentation of the rivers Ganges, Brahmaputra and Meghna, representing largest fluvio-deltaic basin (Holocene-Pleistocene alluvial deposition).…”

Section: Introductionmentioning

confidence: 99%

“…In case of BDP, release of As is believed to be often closely related to release of Mn, but not with Fe and it is driven by microbial process that facilitate reduction of sediment associated elements ( e . g ., As, Fe or Mn) utilizing metabolizable carbon substrates [ 6 ]. Among the various mechanisms proposed, release of As due to weathering and/or dissolution of host minerals (Fe/Mn-oxides hydroxides) by complex geomicrobiolgical activities remains the most significant [ 11 ].…”

Section: Introductionmentioning

confidence: 99%

“…It has been hypothesized that both quantity and quality of labile organic matter and electron donor required for driving the As mobilization reactions are important for microbial action [ 15 ]. The combination of local hydrological and geochemical conditions and microbial processes that allow utilization of available organic carbons ‘foster the development of specific redox zones’ within the aquifer allowing mobilization of As [ 6 , 24 ]. Apart from organic carbon, the role of inorganic electron donors ( e .…”

Section: Introductionmentioning

confidence: 99%

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Diversity, Metabolic Properties and Arsenic Mobilization Potential of Indigenous Bacteria in Arsenic Contaminated Groundwater of West Bengal, India

et al. 2015

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Arsenic (As) mobilization in alluvial aquifers is caused by a complex interplay of hydro-geo-microbiological activities. Nevertheless, diversity and biogeochemical significance of indigenous bacteria in Bengal Delta Plain are not well documented. We have deciphered bacterial community compositions and metabolic properties in As contaminated groundwater of West Bengal to define their role in As mobilization. Groundwater samples showed characteristic high As, low organic carbon and reducing property. Culture-independent and -dependent analyses revealed presence of diverse, yet near consistent community composition mostly represented by genera Pseudomonas, Flavobacterium, Brevundimonas, Polaromonas, Rhodococcus, Methyloversatilis and Methylotenera. Along with As-resistance and -reductase activities, abilities to metabolize a wide range carbon substrates including long chain and polyaromatic hydrocarbons and HCO3, As3+ as electron donor and As5+/Fe3+ as terminal electron acceptor during anaerobic growth were frequently observed within the cultivable bacteria. Genes encoding cytosolic As5+ reductase (arsC) and As3+ efflux/transporter [arsB and acr3(2)] were found to be more abundant than the dissimilatory As5+ reductase gene arrA. The observed metabolic characteristics showed a good agreement with the same derived from phylogenetic lineages of constituent populations. Selected bacterial strains incubated anaerobically over 300 days using natural orange sand of Pleistocene aquifer showed release of soluble As mostly as As3+ along with several other elements (Al, Fe, Mn, K, etc.). Together with the production of oxalic acid within the biotic microcosms, change in sediment composition and mineralogy indicated dissolution of orange sand coupled with As/Fe reduction. Presence of arsC gene, As5+ reductase activity and oxalic acid production by the bacteria were found to be closely related to their ability to mobilize sediment bound As. Overall observations suggest that indigenous bacteria in oligotrophic groundwater possess adequate catabolic ability to mobilize As by a cascade of reactions, mostly linked to bacterial necessity for essential nutrients and detoxification.

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Reconstructing the sedimentation history of the Bengal Delta Plain by means of geochemical and stable isotopic data

Cited by 27 publications

References 46 publications

Investigating Fluorescent Organic-Matter Composition as a Key Predictor for Arsenic Mobility in Groundwater Aquifers

Investigating Fluorescent Organic-Matter Composition as a Key Predictor for Arsenic Mobility in Groundwater Aquifers

Biogeochemical Controls on the Release and Accumulation of Mn and As in Shallow Aquifers, West Bengal, India

Diversity, Metabolic Properties and Arsenic Mobilization Potential of Indigenous Bacteria in Arsenic Contaminated Groundwater of West Bengal, India

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