Characterisation of shallow groundwater dissolved organic matter in aeolian, alluvial and fractured rock aquifers

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dc.contributor.authorMcDonough, LKen_AU
dc.contributor.authorRutlidge, Hen_AU
dc.contributor.authorO’Carroll, DMen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorBenkhe, MIen_AU
dc.contributor.authorSpencer, RGMen_AU
dc.contributor.authorMcKenna, AMen_AU
dc.contributor.authorMarjo, CEen_AU
dc.contributor.authorOudone, PPen_AU
dc.contributor.authorBaker, AAen_AU
dc.date.accessioned2023-02-10T01:41:59Zen_AU
dc.date.available2023-02-10T01:41:59Zen_AU
dc.date.issued2020-03-15en_AU
dc.date.statistics2022-11-25en_AU
dc.description.abstractGroundwater organic matter is processed within aquifers through transformations such as the adsorption of dissolved organic matter (DOM) to minerals and biodegradation. The molecular character of DOM varies according to its source and this can impact its bioavailability and reactivity. Whilst the character of DOM in riverine and oceanic environments is increasingly well understood, the sources, character and ultimately the fate of groundwater DOM remains unclear. Here we examine groundwater DOM from contrasting hydrogeological settings in New South Wales, Australia. For the first time, we identify the distinct molecular composition of three groundwater DOM end-members including a modern terrestrial input, an aged sedimentary peat source, and an aged stable by-product pool. We also identify and characterise the processing pathway of DOM in semi-arid, low sedimentary organic carbon (OC) environments. Based on size exclusion chromatography, ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS), isotopic analyses (13C, 14C and 3H) and principle component analysis (PCA), we show that in higher rainfall temperate coastal peatland environments, large amounts of aged sedimentary organic carbon can leach into groundwater resulting in higher molecular weight (500 g mol−1 < molecular weight > 1000 g mol−1) and highly aromatic groundwater DOM with high O/C ratios and low H/C ratios. We show that in semi-arid environments with low rainfall rates and high groundwater residence times, groundwater dissolved organic carbon (DOC) is processed into increasingly low molecular weight (<350 g mol−1), low aromaticity DOM with low O/C ratios and high H/C ratios by subsurface processing mechanisms such as biodegradation and adsorption. We provide the first comprehensive study of groundwater DOM characterisation based on multiple analytical techniques, and highlight the impact of source inputs and processing on groundwater DOM composition at a molecular level. Crown Copyright © 2020 Published by Elsevier Ltden_AU
dc.description.sponsorshipThis research was supported by the Australian Research Council [Discovery Project number DP160101379]; the Australian Government Research Training Program and Australian Nuclear Science Technology Organisation (ANSTO); Centre for Accelerator Science at ANSTO, the Australia National Collaborative Research Infrastructure Strategy (NCRIS) which funded the installation of bores at Wellington and Maules Creek; the NSW Department of Primary Industries Office of Water for bore infrastructure at Anna Bay and the National Centre for Groundwater Research and Training (NCGRT). A portion of this work was performed at the National High Magnetic Field Laboratory ICR User Facility, which is supported by the National Science Foundation Division of Chemistry through DMR-1644779, DMR-1157490 and the State of Florida.en_AU
dc.identifier.citationMcDonough, L. K., Rutlidge, H., O'Carroll, D. M., Andersen, M. S., Meredith, K., Behnke, M. I., Spencer, R. G. M., McKenna, A. M., Marjo, C. E., Oudone, P. & Baker, A. (2020). Characterisation of shallow groundwater dissolved organic matter in aeolian, alluvial and fractured rock aquifers. Geochimica et Cosmochimica Acta, 273, 163-176. doi:10.1016/j.gca.2020.01.022en_AU
dc.identifier.issn0016-7037en_AU
dc.identifier.journaltitleGeochimica et Cosmochimica Actaen_AU
dc.identifier.pagination163-176en_AU
dc.identifier.urihttps://doi.org/10.1016/j.gca.2020.01.022en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/14646en_AU
dc.identifier.volume273en_AU
dc.language.isoenen_AU
dc.publisherElsevieren_AU
dc.subjectGround wateren_AU
dc.subjectCarbonen_AU
dc.subjectAquifersen_AU
dc.subjectAdsorptionen_AU
dc.subjectNew South Walesen_AU
dc.subjectAustraliaen_AU
dc.titleCharacterisation of shallow groundwater dissolved organic matter in aeolian, alluvial and fractured rock aquifersen_AU
dc.typeJournal Articleen_AU
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