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| Titel |
Assessment of submarine groundwater discharge and associated dissolved inorganic carbon into a coastal wetland, western Taiwan via time-series observations of ²²²Rn |
| VerfasserIn |
Feng-Hsin Hsu, Chih-Chieh Su, Pei-Ling Wang |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144398
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| Publikation (Nr.) |
 EGU/EGU2017-8217.pdf |
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| Zusammenfassung |
| We investigated submarine groundwater discharge (SGD) and associated dissolved inorganic
carbon flux into the Gaomei wetland, which is located south of the Tachia river’s mouth,
western Taiwan. This area is characterized by a great tidal range (over 3 m at spring tide) and
a shallow unconfined aquifer (∼2 m below the seafloor) with high groundwater
recharging rates (over 500 mm yr−1) in the hinterland. In this study we argue that in the
Gaomei wetland, tidal pumping causes an exchanging between groundwater and
seawater, resulting in an overall dissolved inorganic carbon (DIC) flux into the
wetland.
Time-series observations of 222Rn were conducted over 2 tidal cycles in both dry (May of
2014) and wet seasons (August of 2014) seasons at a station 500 m offshore. Our result
shows a good response to tidal fluctuation with higher 222Rn activities at low tide and lower
222Rn activities at high tide. Based on a 222Rn mass balance model taking all sources and
sinks into account, we estimated a SGD flux ranging from -3.86 to 69 cm d−1 with slightly
higher fluxes during the wet season (average SGD flux 22 cm d−1) compared to the dry
season (average SGD flux 16 cm d−1). Our negative SGD flux estimates observed during
high tides suggest that seawater infiltrates into the sediments during flood tide and discharges
during ebb tide, proving the concept of seawater exchange across the water-sediment
interface.
The overall SGD-borne DIC fluxes range between 1.82×106 and 2.48×106 mol d−1 in
dry and wet seasons, respectively, that are 26 % and 36 % of the river-induced DIC fluxes.
Such an export of DIC flux from the groundwater (or recycled seawater) might have an
impact on coastal biogeochemistry in the Gaomei wetland. |
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