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Distribution and Biogeochemical Cycling of Arsenic In Grey and Brown Sand Aquifers in the Bengal Delta Plains (India)
Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
2016 (English)Doctoral thesis, comprehensive summary (Other academic)Alternative title
Distribution och biogeokemiska cykler av Arsenik i grått och brunt sand akviferer i Bengal Delta Plains (Indien) (Swedish)
Abstract [en]

An elevated level of Arsenic (As) in aquifers from India and Bangladesh affecting the human health has been widely reported since the late 1980s. The thesis aim is to investigate the present status of As contamination and biogeochemical cycling with direct role of diverse indigenous bacterial communities in As cycling in the Bengal Delta Plain (BDP) aquifers in Nadia district, West Bengal (India). The As(III) oxidizing bacterial communities were predominant in grey sand aquifers (GSA), but were characteristically absent in brown sand aquifers (BSA). Rainwater recharge containing inorganic and organic dissolved compounds played an important role in shaping the different groups of bacterial phenotypes. It included thearsenite-oxidizing bacteria as revealed by the aioA and 16S rRNA phylogeny. These bacterial communities in BDP groundwater were assumed to utilize the dissolved and sedimentary organic carbon (DOC and SOC) as the primary carbon source for respiration, and remobilization/immobilization of As involving reductive dissolution of iron oxyhydroxides. Hence, sediment and groundwater of these aquifer waters were characterized for their different inorganic constituents (metals) and organic compound classes. There were notable differences between the groundwater DOC and SOC pools. The only similarity between these carbon pools is presence of petroleum-derived hydrocarbons. The SOC in BSA has good correlation with the clay and silt-rich fraction. Notably, As formed complexes with iron, but not manganese. Biomarker characterization in sediments showed presence of terrigenous inputs along with petroleum-derived hydrocarbons. However, these hydrocarbons were absent in BSA sediments, and so were the arsenite oxidizing bacterial communities. Although DOC in groundwater plays an important role in sustaining the microorganisms, the contrasting character of SOC in BSA and GSA strongly influence the shaping of microbial community structure and biogeochemical cycling of As. This particularly affects the natural ‘safe’ drinking water capacity. Overall, the study gives a new directionfor long-term research on As biogeochemical cycling in the contaminated BDP aquifers.

Abstract [sv]

Sedan 1980-talet har förhöjda nivåer av arsenik (As) uppmätts i akvifärer i Indien och Bangladesh, vilket kan orsaka stora hälsoproblem då arsenik är giftigt för människor. Syftet med denna avhandling är både att undersökaaktuell föroreningsstatus av As i akvifärer i det Bengaliska Deltat (BDP), Nadia distriktet, Västbengalen (Indien) och att undersöka As biogeokemiskaomsättningsamt roll i olika inhemska bakteriella samhällen. Resultaten visar att As (III) oxiderande bakteriesamhällen var dominerande i grå akvifärsand (GSA), men hittades intei brun akvifärsand (BSA). Det visar sig också att tillförsel av regnvatten med oorganiska och organiska lösta föreningar spelar en viktig roll för att skapaolika grupper av bakteriella fenotyperdärarsenitoxiderande bakterier ingick vilket framkommedaioA och 16S rRNA fylogeni. Dessa bakteriesamhällen i BDPs grundvatten utnyttjar troligtvis det upplösta och sedimentära organiska kolet (DOC och SOC) som primär kolkälla för andning, och hjälper till att lösa upp järnhydroxidervid mobilisering av As. Därför kan sediment och grundvatten i dessa grundvattenakvifärer karaktäriseras genomderas olika oorganiska beståndsdelar (metaller) och organiska föreningar. Det fanns ocksåtydliga skillnader mellan DOC och SOC pooler i grundvatten och akvifärmaterial. Den enda likheten mellan dessa kolpooler är förekomst av petroleumbaserade kolväten. SOC i BSA korrelerar med ler- och siltfraktioner. Vidare såbildades As komplex med järn, men inte med mangan. Karakterisering med hjälp av biomarkörer i sediment visade närvaro av terrestra samt och petroleumbaserade kolväten. Dessa kolväten hittades inte i sediment från BSA, och inte heller arsenitoxiderande bakteriesamhällen. Även om DOC i grundvatten spelar en viktig roll förmikroorganismerna, så påverkar olika SOC i BSA och GSA de  mikrobiella samhällsstrukturerna och den biogeokemiska omsättningen av As. Detta påverkarsärskilt den naturligt "säkra" dricksvattenkapaciteten. Sammantaget ger studien en ny riktning för långsiktig forskning om As biogeokemiska cykel i förorenade BDP akvifärer.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2016. , 80 p.
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 670
Keyword [en]
Arsenic, aquifer, arsenite oxidation, aioA gene, Bengal delta plains, biogeochemical cycling biomarkers, DOC, SOC
Keyword [sv]
Arsenik, akvifärer, arsenitoxiderande, aioA gene, Bengal delta plains, biogeokemiska omsättning, biomarkörer, DOC, SOC
National Category
Geochemistry Water Treatment Microbiology Geosciences, Multidisciplinary Water Engineering Environmental Sciences
URN: urn:nbn:se:liu:diva-126598ISBN: 978-91-7685-830-1 (Print)OAI: diva2:915764
Public defence
2016-03-22, TEMCAS, T- House, Campus Valla, Linköping, 13:00 (English)
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2016-06-14Bibliographically approved
List of papers
1. Arsenic Contamination in Soil and Sediment in India: Sources, Effects, and Remediation
Open this publication in new window or tab >>Arsenic Contamination in Soil and Sediment in India: Sources, Effects, and Remediation
2015 (English)In: Current Pollution Reports, ISSN 2198-6592, Vol. 1, no 1, 35-46 p.Article in journal (Refereed) Published
Abstract [en]

Arsenic contamination is turning out to be a major problem these days with its area coverage and the number of people affected directly or indirectly. Now, the level of the contaminant has spread over the soil and sediments from groundwater and other natural sources. Arsenic poisoning in groundwater events is familiar to the world, but the consequences of soil contamination are still unrevealed to the community, specially the people of contaminated counties. Arsenic is a serious instantaneous concern for the people and other life forms regarding the poisoning through crops and vegetables. Many remediation technologies that mainly include physical, chemical, and a few biological methods have been evolved with time to check its effects. The physical and chemical methods for this purpose are often inefficient and/or very expensive, mainly limited to application in aqueous systems, and produce toxic sludge, which again becomes a matter of concern. But bioremediation relies on the fact that biological organisms have the ability to degrade, detoxify, and even accumulate harmful chemicals and offers attractive perspectives for biomonitoring (via biosensors), treatment of wastewater, and the recycling of polluted soils.

Place, publisher, year, edition, pages
Springer, 2015
National Category
Environmental Sciences Soil Science Water Engineering Geochemistry Water Treatment Environmental Sciences related to Agriculture and Land-use
urn:nbn:se:liu:diva-126596 (URN)10.1007/s40726-015-0004-2 (DOI)
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2016-03-31Bibliographically approved
2. Diversity of arsenite oxidizing bacterial communities in arsenic-rich deltaic aquifers in West Bengal, India
Open this publication in new window or tab >>Diversity of arsenite oxidizing bacterial communities in arsenic-rich deltaic aquifers in West Bengal, India
2014 (English)In: Frontiers in Microbiology, ISSN 1664-302X, Vol. 5, no 602, 1-14 p.Article in journal (Refereed) Published
Abstract [en]

High arsenic (As) concentration in groundwater has affected human health, particularly in South-East Asia putting millions of people at risk. Biogeochemical cycling of As carried out by different bacterial groups are suggested to control the As fluxes in aquifers. A functional diversity approach in link with As precipitation was adopted to study bacterial community structures and their variation within the As contaminated Bengal Delta Plain (BDP) aquifers of India. Groundwater samples collected from two shallow aquifers in Karimpur II (West Bengal, India), during years 2010 and 2011, were investigated to trace the effects immediately after monsoon period (precipitation) on community structure and diversity of bacterial assemblages with a focus on arsenite oxidizing bacterial phyla for two successive years. The study focused on amplification, clone library generation and sequencing of the arsenite oxidase large sub-unit gene aioA and 16S rRNA marker, with respect to changes in elemental concentrations. New set of primers were designed to amplify the aioA gene as a phylogenetic marker to study taxonomically diverse arsenite oxidizing bacterial groups in these aquifers. The overall narrow distribution of bacterial communities based on aioA and 16S rRNA sequences observed was due to poor nutrient status and anoxic conditions in these As contaminated aquifers. Proteobacteria was the dominant phylum detected, within which Acidoyorax, Hydrogenophaga, Albidiferax, Bosea, and Polymorphum were the major arsenite oxidizing bacterial genera based on the number of clones sequenced. The structure of bacterial assemblages including those of arsenite oxidizing bacteria seems to have been affected by increase in major elemental concentrations (e.g., As, Fe, S, and Si) within two sampling sessions, which was supported by statistical analyses. One of the significant findings of this study is detection of novel lineages of 16S rRNA-like bacterial sequences indicating presence of indigenous bacterial communities BDP wells that can play important role in biogeochemical cycling of elements including As.

Place, publisher, year, edition, pages
Frontiers, 2014
Arsenic; aquifer; arsenite oxidation; aioA gene; phylogeny
National Category
Earth and Related Environmental Sciences
urn:nbn:se:liu:diva-113200 (URN)10.3389/fmicb.2014.00602 (DOI)000345856200001 ()25484877 (PubMedID)

Funding Agencies|Swedish Research Link-Asia Program; Department of Science and Technology (DST), Government of India; DST

Available from: 2015-01-13 Created: 2015-01-12 Last updated: 2016-03-31
3. Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)
Open this publication in new window or tab >>Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)
2015 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 527, 221-233 p.Article in journal (Refereed) Published
Abstract [en]

The coupled role of organic matter (OM) and microbial activity is widely acknowledged in arsenic (As) biogeochemical cycling in sedimentary environments. However, little is known about OM characteristics particularly the dissolved fraction in the Bengal Delta Plain aquifers – one of the worst As impacted regions in the world. Ongoing investigations in As-rich aquifers in Nadia district (West Bengal, India) indicate presence of arsenite As(III) oxidizing bacterial communities in the Grey Sand Aquifers (GSA), but absent in Brown Sand Aquifers (BSA). In this study, we investigate the key differences in dissolved organic carbon (DOC) characteristics and its relationship with differences in elemental concentrations, distribution of biomarkers, and utilization of DOC by in situ microbial communities in BSA and GSA. We demonstrate a new approach using ENVI™ C-18 DSK discs to pre-concentrate DOC from large volumes of water, and further extract the OM and separate it into different lipid fractions using the solid phase extraction technique. The aquifers show marked heterogeneity in terms of their DOC characteristics and elemental profiles irrespective of their grey or brown color. DOC indicates variable inputs of terrestrial derived OM sources, and OM derived from decomposition and/or microbial cellular components. DOC in the aquifers consist of predominantly n-alkanoic acids (∌80%) followed by n-alkanes and n-alcohols. The GSAs indicate high iron (Fe) and manganese (Mn) concentrations, and presence of mature petroleum derived hydrocarbons in DOC. BSA has comparatively lower concentrations of Fe and Mn, and shows absence of mature hydrocarbons in DOC. Experiments in presence of indigenous bacteria from groundwater with DOC lipid extracts as the sole carbon source indicate higher growth in the GSA samples implying preferential use of DOC. The potential availability of DOC in these aquifers can influence the community composition of indigenous heterotrophic microbial flora, which in turn can affect elemental cycles including that of As.

Arsenic, Aquifers, DOC, Microbes, Aquatic biomarkers
National Category
Geochemistry Water Treatment Analytical Chemistry Microbiology Water Engineering Environmental Sciences
urn:nbn:se:liu:diva-126597 (URN)10.1016/j.jhydrol.2015.04.051 (DOI)000358629100021 ()
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2016-08-22Bibliographically approved
4. Elemental and biomarker characteristics in a Pleistocene aquifer vulnerable to arsenic contamination in the Bengal Delta Plain, India
Open this publication in new window or tab >>Elemental and biomarker characteristics in a Pleistocene aquifer vulnerable to arsenic contamination in the Bengal Delta Plain, India
2015 (English)In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 61, 87-98 p.Article in journal (Refereed) Published
Abstract [en]

An elevated level of arsenic (As) in the Indo-Gangetic delta plain aquifers has been reported since the 1990s. Organic matter (OM) present in groundwater and aquifer sediments supports the microbial communities in these aquifers. During installation of a drinking water well, 26 sediment intervals of 6 m each were retrieved up till 156 m from a Pleistocene brown sand aquifer (BSA). Grain size distribution, sequential extraction of metals and total extractable lipids were analyzed in each sample. These parameters were statistically correlated in order to establish relationship between the physical vs. inorganic and organic characteristics, and how these properties affected the distribution of As in BSAs. The aquifer sediments consisted of medium to coarse sand except the surface sediments and those at the bottom of the well, which had high clay and slit content. Arsenic (As) concentration in sediments ranged from 2 to 21 mg/kg and indicated a strong correlation with grain size. Arsenic was mostly associated with crystalline oxides and silicate-rich minerals. Arsenic showed significant correlation with Fe in all fractions, and suggests presence of pyrite bound As-bearing minerals in these sediments. The diagnostic sedimentary lipid biomarkers indicated presence of compounds derived from vascular plants and microbial cell wall. This inference was supported by various diagnostic lipid ratios. The biomarkers were abundant in surface and deeper layers, which had high clay and silt content. The BSA sediments indicated preferential preservation of n-alkanes over other functional compounds, which were more reactive and subject to degradation. The thick clay layer at 132-156 m contained visible plant fragments, and OM in this layer indicated preferential preservation of organic carbon most likely due to the absence of specific microbial communities that degraded these compounds and mobilized As. Statistical analyses indicated the influence of selective inorganic and organic components (As, Fe and fatty acids) controlling the co-distribution of various inorganic and organic components in the aquifer.

Place, publisher, year, edition, pages
National Category
Earth and Related Environmental Sciences
urn:nbn:se:liu:diva-122048 (URN)10.1016/j.apgeochem.2015.05.007 (DOI)000360654200008 ()

Funding Agencies|Department of Science and Technology, Government of India; Swedish Research Link-Asia Program [2009-6470]; Linkoping University, Sweden

Available from: 2015-12-18 Created: 2015-10-19 Last updated: 2016-05-27

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