Natural organic matter in groundwater: carbon source or sink ?

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dc.contributor.authorRutlidge, Hen_AU
dc.contributor.authorMcDonough, LKen_AU
dc.contributor.authorOudone, PPen_AU
dc.contributor.authorAndersen, MSen_AU
dc.contributor.authorBaker, AAen_AU
dc.contributor.authorMeredith, KTen_AU
dc.contributor.authorO'Carroll, DMen_AU
dc.contributor.authorMarjo, CMen_AU
dc.contributor.authorMustonen, Oen_AU
dc.date.accessioned2024-05-08T01:05:24Zen_AU
dc.date.available2024-05-08T01:05:24Zen_AU
dc.date.issued2019-04-08en_AU
dc.date.statistics2023-03-24en_AU
dc.description.abstractCarbon plays an essential role in all biological processes on the earth and hence it is important to Mustin the environment. The concentration of organic matter in groundwater, with a global median of 1.0 mg C/L, is often significantly lower than in adjacent soil and surface waters. The likely processes that are responsible for this decrease are sorption to mineral surfaces and biological processing by microbes as water travels through sediments. While these processes have been quantified individually at different sites, they have not been investigated concurrently, and hence the relative importance of each process is unknown. Therefore, the role of organic matter processes in groundwater and in the terrestrial global carbon budget is unknown. To investigate this a series of laboratory-based experiments were conducted, in conjunction with the organic matter characterization of field samples by Liquid Chromatography-Organic Carbon Detection (LC-OCD). LC-OCD is a size-exclusion based chromatography technique that separates dissolved organic carbon into five fractions based on their mass, plus a hydrophobic fraction, which remains in the column. For the laboratory-based experiments, the amount of sorption onto pure mineral surfaces (quartz sand, iron-coated sand, and calcium carbonate), desorption from natural sediments and biological degradation was investigated at a range of different locations in New South Wales, Australia. The sites covered a range of different aquifer materials (coastal sands, river alluvium and fractured meta-basalts), land cover and recharge type. At each site, groundwater samples were collected from wells located with varying distance from surface water bodies for the subsequent laboratory experiments. The results showed that predominately the humics fraction was adsorbing onto the mineral surfaces and the low-molecular weight neutrals were being biologically degraded. For the desorption experiments several fractions desorbed with the humics and hydrophobic fraction being dominant. The amount of desorption increased with increasing salinity and increasing number of cycles of drying and wetting. The LC-OCD results of field samples indicated that proportionally, sorption is more dominant than biological degradation. Hence changing environmental conditions, such as increasing salinity and/or drier conditions, could lead to a release of sorbed carbon.en_AU
dc.identifier.articlenumberEGU2019-6482en_AU
dc.identifier.booktitleGeophysical Research Abstractsen_AU
dc.identifier.citationRutlidge, H., McDonough, L., Oudone, P., Andersen, M. S., Baker, A., Meredith, K., O'Carroll, D., Marjo, C. E., & Mustonen, O. (2019). Natural organic matter in groundwater: carbon source or sink ?. Paper presented to the EGU General Assembly 2019, Vienna, Austria, 7-12 April 2019. In Geophysical Research Abstracts, Vol. 21, EGU2019-6482. Retrieved from: https://meetingorganizer.copernicus.org/EGU2019/EGU2019-6482.pdfen_AU
dc.identifier.conferenceenddate2019-04-12en_AU
dc.identifier.conferencenameEGU General Assembly 2019en_AU
dc.identifier.conferenceplaceVienna, Austriaen_AU
dc.identifier.conferencestartdate2019-04-07en_AU
dc.identifier.otherEGU2019-6482en_AU
dc.identifier.urihttps://meetingorganizer.copernicus.org/EGU2019/EGU2019-6482.pdfen_AU
dc.identifier.urihttps://apo.ansto.gov.au/handle/10238/15589en_AU
dc.identifier.volume21en_AU
dc.language.isoenen_AU
dc.publisherCopernicus GmbHen_AU
dc.subjectOrganic matteren_AU
dc.subjectGround wateren_AU
dc.subjectCarbonen_AU
dc.subjectCarbon sinksen_AU
dc.subjectEarth planeten_AU
dc.subjectSoilsen_AU
dc.subjectSurface watersen_AU
dc.subjectChromatographyen_AU
dc.titleNatural organic matter in groundwater: carbon source or sink ?en_AU
dc.typeConference Abstracten_AU
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