Tracing organic carbon processes in a shallow coastal sandy aquifer
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Date
2017-12-14
Journal Title
Journal ISSN
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Publisher
American Geophysical Union (AGU)
Abstract
Coastal groundwater resources are likely to be impacted by climate change due to changes in recharge patterns, surface water flow and sea-level rise, which all have the potential to change how carbon is transported and stored within a catchment. Large quantities of carbon are currently stored within coastal wetland systems, so understanding carbon dynamics is important for climate change predictions into the future. Furthermore, dissolved organic carbon (DOC) can play a major role in weathering processes and deterioration of water quality, therefore understanding the sources, degradation pathways and its reactivity is important.
Groundwater samples were collected from five nested sites (15 wells) from a shallow (0-20m) coastal sandy aquifer system located at Anna Bay, New South Wales, Australia. Surface water samples were also collected from the adjacent wetland. Waters were measured for major ion chemistry, carbon isotopes (δ13CDIC, δ13CDOC and 14CDIC) and tritium (3H). The dissolved organic matter (DOM) character was determined using optical spectroscopy and liquid chromatography. DOC was found to be elevated in the wetland (18 ppm) and had the lowest δ13CDOC value (-30.3 ‰). The shallow (3.5 m) groundwater located closest to but downgradient of the wetland (5 m) had similar characteristics to the wetland sample but contained significantly lower DOC concentrations (5 ppm) and were 1 ‰ more enriched in δ13CDOC values. This suggests that the aquifer is a sink for organic matter and the process fractionates the carbon isotopes. Higher resolution studies are underway to characterise and constrain timescales for the DOC transformation processes.
Description
Keywords
Tracer techniques, Ground water, Carbon, Aquifers, Coastal regions, Climatic change
Citation
Meredith, K., Andersen, M. S., Baker, A., O'Carroll, D. M., Bryan, E., Zainuddin, N. S., Rutlidge, H., & McDonough, L. (2017). Tracing organic carbon processes in a shallow coastal sandy aquifer. Poster presented at the AGU Fall Meeting, 2017, New Orleans, Louisiana, USA, 11-15 December 2017. In AGU Fall Meeting Abstracts, Vol. 2017, B42B-03. Retrieved from: https://agu.confex.com/agu/fm17/meetingapp.cgi/Paper/246905