Balancing the terrestrial global carbon budget has proven to be a significant challenge. Whilst the movement of carbon in the atmosphere and riverine waters has been extensively studied, the potential for groundwater to act as a source or sink for organic carbon is poorly understood. Our research summarises both published and unpublished datasets of dissolved organic carbon (DOC) concentrations in groundwater, both within Australia and globally, to gain an understanding of the factors that affect groundwater DOC concentrations. Our findings indicate that areas of Australia have relatively high DOC concentrations when placed in a global context. Results also suggest that concentrations of DOC decrease with increased distance from rivers and wetlands, with increased DOC concentrations positively correlated with heavier δ<sup>13</sup>C-DOC isotopic signatures in some locations. This is likely to be a result of groundwater chemistry, host rock geology and groundwater microbiology. This research forms part of an ongoing project which will assist in identifying the factors affecting the mobilisation, transport and removal of DOC in uncontaminated groundwater, and ultimately lead to a better understanding of the importance of groundwater organic carbon to the global carbon budget.

Factors affecting the fate of dissolved organic carbon in groundwater

253rd National Meeting (2017)

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