Using radioactive and stable carbon isotopes, LC-OCD and FT-ICR MS to understand groundwater organic carbon sources and processing

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dc.contributor.authorMcDonough, LKen_AU
dc.contributor.authorOudone, PPen_AU
dc.contributor.authorRutlidge, Hen_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorO'Carroll, DMen_AU
dc.contributor.authorBehnke, MIen_AU
dc.contributor.authorSpencer, RGMen_AU
dc.contributor.authorBaker, AAen_AU
dc.date.accessioned2023-06-30T01:24:27Zen_AU
dc.date.available2023-06-30T01:24:27Zen_AU
dc.date.issued2019-04-07en_AU
dc.date.statistics2023-03-23en_AU
dc.description.abstractDissolved organic matter (DOM) concentrations typically decrease from surface to groundwater, which suggests that most groundwater DOM is sourced from the surface. DOM undergoes many removal processes in the subsurface, including sorption to mineral surfaces, biodegradation, and filtration as it moves through soils, sediment and bedrock. In addition, there is potential for subsurface sediments to act as a source of organic carbon in groundwater. However, relatively little is understood about the character of sedimentary organic carbon sources and how DOM character changes as it undergoes processing along a flow path. We obtained 21 groundwater samples and 3 surface water samples from two alluvial aquifers and one coastal sand aquifer in New South Wales, Australia. Samples were analysed for 14C and 3H to identify groundwater recharge sources, flow paths and water residence times. Radioactive (14C) and stable (13C/12C) carbon isotopes, liquid chromatography organic carbon detection (LC-OCD) and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) were used to characterise DOM and determine DOM source and processing mechanisms. For our coastal aquifer we identify a decrease in low molecular weight neutrals (LMW-N), peptide-like, aliphatic, highly unsaturated and phenolic groups, and an increase in condensed aromatics and polyphenolic groups, with increasing DOM age. We attribute this to the contribution of old, unprocessed sedimentary organic carbon in the form of peat associated with the dune-slack morphology of the site. However, the opposite trend was observed for LMW-N, polyphenolic, highly unsaturated and phenolic groups at both inland alluvial aquifers which is likely to be associated with processing of DOM from high to low molecular weight carbon over time at sites dominated by a surface DOM source, with comparatively less sedimentary organic carbon. This research forms part of an ongoing project which will assist in identifying the factors affecting the mobilisation, transport and sources and removal of DOM in groundwater. Importantly, quantification of the change in DOM concentration and character over time, and the relative importance of sedimentary organic carbon as a source of DOM in groundwater will help guide policy and identify the need to include groundwater resources as part of the carbon economy. © Author(s) 2019. CC Attribution 4.0 license.en_AU
dc.identifier.articlenumberEGU2019-11640en_AU
dc.identifier.booktitleGeophysical Research Abstractsen_AU
dc.identifier.citationMcDonough, L., Oudone, P., Rutlidge, H., Meredith, K., Andersen, M., O'Carroll, D., Behnke, M., Spencer, R., & Baker, A. (2019). Using radioactive and stable carbon isotopes, LC-OCD and FT-ICR MS to understand groundwater organic carbon sources and processing. Paper presented to the EGU General Assembly 2019, Vienna, Austria, 7-12 April 2019. In Geophysical Research Abstracts, Vol. 21, EGU2019-11640. Retrieved from: https://meetingorganizer.copernicus.org/EGU2019/EGU2019-11640.pdfen_AU
dc.identifier.conferenceenddate12 April 2019en_AU
dc.identifier.conferencenameEGU General Assembly 2019en_AU
dc.identifier.conferenceplaceVienna, Austriaen_AU
dc.identifier.conferencestartdate7 April 2019en_AU
dc.identifier.urihttps://meetingorganizer.copernicus.org/EGU2019/EGU2019-11640.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15075en_AU
dc.identifier.volume21en_AU
dc.language.isoenen_AU
dc.publisherCopernicus GmbHen_AU
dc.subjectStable isotopesen_AU
dc.subjectGround wateren_AU
dc.subjectCarbonen_AU
dc.subjectSorptionen_AU
dc.subjectSoilsen_AU
dc.subjectOrganic matteren_AU
dc.subjectFiltrationen_AU
dc.subjectUndergrounden_AU
dc.subjectNew South Walesen_AU
dc.subjectAustraliaen_AU
dc.titleUsing radioactive and stable carbon isotopes, LC-OCD and FT-ICR MS to understand groundwater organic carbon sources and processingen_AU
dc.typeConference Abstracten_AU
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