Poster Presentation Australasian Groundwater Conference 2017

The role of dissolved organic matter and groundwater biogeophysical processes in the carbon budget (#90)

Phetdala P OUDONE 1 , Andy A Baker 2 3 , Denis D O'Carroll 3 4 , Martin M Andersen 4 5 , Helen H Rutlidge 3 4 , Liza L McDonough 2 3 , Christ C Marjo 6 , Karina Meredith 7
  1. University of New South Wales, Kingsford, NEW SOUTH WALES, Australia
  2. School of Biological Earth and Environmental Sciences, University of New South Wales, NSW 2052, Sydney, Australia
  3. Connected Waters Initiatives Research Center, University of New South Wales, 110 King Street, Manly Vale, NSW 2093, Sydney, Australia
  4. School of Civil and Environmental Engineering, University of New South Wales, NSW 2052, Sydney, Australia
  5. Connected Waters Initiatives Research Center, UNSW, 110 King Street, Manly Vale, NSW, Sydney, Australia
  6. Mark Wainwright Analytical Centre, University of New South Wales, NSW 2052, Sydney, Australia
  7. Australian Nuclear Science and Technology Organization, New Illawarra Rd, Lucas Heights , NSW 2234, Sydney, Australia

Atmospheric CO2 concentration is acknowledged to play an important role in climate change. However, quantifying more accurate predictions requires a sound understanding of the cycle and process of carbon especially in the environment. There has been extensive research on terrestrial carbon and the different conditions where it is a source or sink. However, the knowledge on whether groundwater organic matter is a carbon source or sink is limited. This work will explore the dynamic of groundwater organic matter including both its concentration and its rate and extent of biological processing and sorption. The UNSW Wellington Research Station was selected for groundwater sampling as it represents a fractured rock aquifer and alluvial aquifer for groundwater property and interaction investigation. Samples were collected from a transect of boreholes perpendicular from the river. Literature procedures were adopted for determining biological dissolved organic carbon and investigation of organic matter sorption on pure minerals (quartz sand, iron-coated quartz sand and calcium carbonate). For each sample collected total dissolved organic concentration was measured and the organic matter present was characterized by fluorescence spectroscopy and size-exclusion chromatographic technique, LC-OCD. There was greater sorption of organic matter with calcium carbonate, followed by iron-coated sand, while minimum sorption was observed with sand. This research in conjunction with similar studies in different environments will allow conclusions to be drawn groundwater organic matter and whether it is a carbon source or sink and thereby the findings can eventually have some policy application which will enable the management of the groundwater resources as part of the carbon economy.  

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