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Characterization and microbial utilization of dissolved lipid organic fraction in arsenic impacted aquifers (India)
Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Laboratory of Integrative Taxonomy and Molecular Ecology, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India.
Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
Laboratory of Integrative Taxonomy and Molecular Ecology, Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, West Bengal, India.
2015 (English)In: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 527, 221-233 p.Article in journal (Refereed) PublishedText
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.

Place, publisher, year, edition, pages
2015. Vol. 527, 221-233 p.
Keyword [en]
Arsenic, Aquifers, DOC, Microbes, Aquatic biomarkers
National Category
Geochemistry Water Treatment Analytical Chemistry Microbiology Water Engineering Environmental Sciences
Identifiers
URN: urn:nbn:se:liu:diva-126597DOI: 10.1016/j.jhydrol.2015.04.051ISI: 000358629100021OAI: oai:DiVA.org:liu-126597DiVA: diva2:915763
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2016-08-22Bibliographically approved
In thesis
1. Distribution and Biogeochemical Cycling of Arsenic In Grey and Brown Sand Aquifers in the Bengal Delta Plains (India)
Open this publication in new window or tab >>Distribution and Biogeochemical Cycling of Arsenic In Grey and Brown Sand Aquifers in the Bengal Delta Plains (India)
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Distribution och biogeokemiska cykler av Arsenik i grått och brunt sand akviferer i Bengal Delta Plains (Indien)
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.
Series
Linköping Studies in Arts and Science, ISSN 0282-9800 ; 670
Keyword
Arsenic, aquifer, arsenite oxidation, aioA gene, Bengal delta plains, biogeochemical cycling biomarkers, DOC, SOC, 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
Identifiers
urn:nbn:se:liu:diva-126598 (URN)978-91-7685-830-1 (Print) (ISBN)
Public defence
2016-03-22, TEMCAS, T- House, Campus Valla, Linköping, 13:00 (English)
Opponent
Supervisors
Available from: 2016-03-31 Created: 2016-03-31 Last updated: 2016-06-14Bibliographically approved

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