Isotopic and chromatographic fingerprinting of the sources of dissolved organic carbon in a shallow coastal aquifer

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dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorBaker, AAen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorO'Carroll, DMen_AU
dc.contributor.authorRutlidge, Hen_AU
dc.contributor.authorMcDonough, LKen_AU
dc.contributor.authorOudone, PPen_AU
dc.contributor.authorBryan, Een_AU
dc.contributor.authorZainuddin, NSen_AU
dc.date.accessioned2020-05-26T05:40:45Zen_AU
dc.date.available2020-05-26T05:40:45Zen_AU
dc.date.issued2020-04-30en_AU
dc.date.statistics2020-05-15en_AU
dc.description.abstractThe terrestrial subsurface is the largest source of freshwater globally. The organic carbon contained within it and processes controlling its concentration remain largely unknown. The global median concentration of dissolved organic carbon (DOC) in groundwater is low compared to surface waters, suggesting significant processing in the subsurface. Yet the processes that remove this DOC in groundwater are not fully understood. The purpose of this study was to investigate the different sources and processes influencing DOC in a shallow anoxic coastal aquifer. Uniquely, this study combines liquid chromatography organic carbon detection with organic (δ13CDOC) carbon isotope geochemical analyses to fingerprint the various DOC sources that influence the concentration, carbon isotopic composition, and character with respect to distance from surface water sources, depth below surface, and inferred groundwater residence time (using 3H activities) in groundwater. It was found that the average groundwater DOC concentration was 5 times higher (5 mg L−1) than the global median concentration and that the concentration doubled with depth at our site, but the chromatographic character did not change significantly. The anoxic saturated conditions of the aquifer limited the rate of organic matter processing, leading to enhanced preservation and storage of the DOC sources from peats and palaeosols contained within the aquifer. All groundwater samples were more aromatic for their molecular weight in comparison to other lakes, rivers and surface marine samples studied. The destabilization or changes in hydrology, whether by anthropogenic or natural processes, could lead to the flux of up to 10 times more unreacted organic carbon from this coastal aquifer compared to deeper inland aquifers. © Author(s) 2020.en_AU
dc.identifier.citationMeredith, K. T., Baker, A., Andersen, M. S., O'Carroll, D. M., Rutlidge, H., McDonough, L. K., Oudone, P., Bryan, E., & Zainuddin, N. S. (2020). Isotopic and chromatographic fingerprinting of the sources of dissolved organic carbon in a shallow coastal aquifer. Hydrology and Earth System Sciences 24(4): 2167-2178. doi:10.5194/hess-24-2167-2020en_AU
dc.identifier.govdoc9561en_AU
dc.identifier.issn1607-7938en_AU
dc.identifier.issue4en_AU
dc.identifier.journaltitleHydrology and Earth System Sciencesen_AU
dc.identifier.pagination2167-2178en_AU
dc.identifier.urihttps://doi.org/10.5194/hess-24-2167-2020en_AU
dc.identifier.urihttp://apo.ansto.gov.au/dspace/handle/10238/9489en_AU
dc.identifier.volume24en_AU
dc.language.isoenen_AU
dc.publisherEuropean Geosciences Unionen_AU
dc.subjectAquifersen_AU
dc.subjectChromatographyen_AU
dc.subjectCarbonen_AU
dc.subjectTerrestrial ecosystemsen_AU
dc.subjectGround wateren_AU
dc.subjectCoastal regionsen_AU
dc.subjectHydrologyen_AU
dc.titleIsotopic and chromatographic fingerprinting of the sources of dissolved organic carbon in a shallow coastal aquiferen_AU
dc.typeJournal Articleen_AU
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