Sadat-Noori, Mahmood, Maher, Damien T., and Santos, Isaac R. (2016) Groundwater Discharge as a Source of Dissolved Carbon and Greenhouse Gases in a Subtropical Estuary. Estuaries and Coasts, 39. pp. 639-656.

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Abstract

Groundwater may be highly enriched in dissolved carbon species, but its role as a source of carbon to coastal waters is still poorly constrained. Exports of deep and shallow groundwater-derived dissolved carbon species from a small subtropical estuary (Korogoro Creek, Australia, latitude −31.0478°, longitude 153.0649°) were quantified using a radium isotope mass balance model (233Ra and 224Ra, natural groundwater tracers) under two hydrological conditions. In addition, air-water exchange of carbon dioxide and methane in the estuary was estimated. The highest carbon inputs to the estuary were from deep fresh groundwater in the wet season. Most of the dissolved carbon delivered by groundwater and exported from the estuary to the coastal ocean was in the form of dissolved inorganic carbon (DIC; 687 mmol m−2 estuary day−1; 20 mmol m−2 catchment day−1, respectively), with a large export of alkalinity (23 mmol m−2 catchment day−1). Average water to air flux of CO2 (869 mmol m−2 day−1) and CH4 (26 mmol m−2 day−1) were 5- and 43-fold higher, respectively, than the average global evasion in estuaries due to the large input of CO2- and CH4-enriched groundwater. The groundwater discharge contribution to carbon exports from the estuary for DIC, dissolved organic carbon (DOC), alkalinity, CO2, and CH4 was 22, 41, 3, 75, and 100 %, respectively. The results show that CO2 and CH4 evasion rates from small subtropical estuaries surrounded by wetlands can be extremely high and that groundwater discharge had a major role in carbon export and evasion from the estuary and therefore should be accounted for in coastal carbon budgets.

Item ID:	78849
Item Type:	Article (Research - C1)
ISSN:	1559-2731
Copyright Information:	© Coastal and Estuarine Research Federation 2015
Funders:	Australian Research Council (ARC)
Projects and Grants:	ARC DE140101733, ARC DE150100581, ARC DP120101645, ARC LE120100156
Date Deposited:	07 Jun 2023 02:12
FoR Codes:	41 ENVIRONMENTAL SCIENCES > 4104 Environmental management > 410402 Environmental assessment and monitoring @ 10% 37 EARTH SCIENCES > 3707 Hydrology > 370703 Groundwater hydrology @ 60% 37 EARTH SCIENCES > 3707 Hydrology > 370704 Surface water hydrology @ 30%
SEO Codes:	18 ENVIRONMENTAL MANAGEMENT > 1803 Fresh, ground and surface water systems and management > 180305 Ground water quantification, allocation and impact of depletion @ 50% 18 ENVIRONMENTAL MANAGEMENT > 1802 Coastal and estuarine systems and management > 180201 Assessment and management of coastal and estuarine ecosystems @ 50%
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