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| Titel |
Analysing Submarine Groundwater Discharge (SGD)-borne Dissolved Organic Matter (DOM) in a karstic aquifer, Co. Galway, Ireland. |
| VerfasserIn |
Tara Kelly, Carlos Rocha |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250096026
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| Publikation (Nr.) |
 EGU/EGU2014-11506.pdf |
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| Zusammenfassung |
| Submarine Groundwater Discharge (SGD) constitutes an "invisible" link between land and
sea, transporting allochthonous and autochthonous dissolved organic matter (DOM), nutrients
and metals to the ocean via the subterranean estuary. The latter acts as a powerful bioreactor
where groundwater, in transit from land to sea, mixes with seawater leading to
active modulation of both DOM content and chemical makeup of SGD. DOM in
freshwater systems is a key component of the global carbon cycle. Climate change may
hence increase the concentration of allochthonous carbon entering the oceans as
terrestrial DOC is released from soils at higher temperatures, and transported via SGD.
Presently, little is known about the effects of SGD-borne DOM on coastal carbon
cycling.
SGD therefore represents a dynamic reservoir and analysis is critical to forecast future
environmental management programmes, both on a local and global scale. Labile DOM plays
a crucial role in microbial remineralisation processes, and as it breaks down it contributes to
the groundwater nutrient pool. Locally, this could add to eutrophication. However, if
refractory carbon is present, it will be recalcitrant to mineralisation in transit and at the
subterranean estuary. This putative additional input will thus imply the contribution of SGD
to oceanic carbon storage.
This study is focused on Kinvara Bay (Galway, western Ireland), the focal point for
waters discharging from the Gort-Kinvara karstic aquifer. This aquifer represents the ideal
study location for evaluation of SGD contribution to the coastal DOM pool, as SGD is
focused in the bay, surface drainage is very limited, and groundwater travels across a large
catchment area with a short residence time, minimising DOM modification in transit. DOM
samples collected in the field have been analysed using Three-Dimensional Excitation
Emission Matrix Fluorescence (3D-EEMF) and High Temperature Catalytic Oxidation.
PARAFAC is subsequently used as a tool to elucidate the types, sources (marine vs
terrigeneous) and fractional composition of DOM, both in SGD plumes and in surface waters. |
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