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| Titel |
Groundwater and porewater as major sources of alkalinity to a fringing coral reef lagoon (Muri Lagoon, Cook Islands) |
| VerfasserIn |
T. Cyronak, I. R. Santos, D. V. Erler, B. D. Eyre |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 4 ; Nr. 10, no. 4 (2013-04-15), S.2467-2480 |
| Datensatznummer |
250018197
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| Publikation (Nr.) |
 copernicus.org/bg-10-2467-2013.pdf |
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| Zusammenfassung |
| To better predict how ocean acidification will affect coral reefs, it is
important to understand how biogeochemical cycles on reefs alter carbonate
chemistry over various temporal and spatial scales. This study quantifies the
contribution of shallow porewater exchange (as quantified from advective
chamber incubations) and fresh groundwater discharge (as traced by
222Rn) to total alkalinity (TA) dynamics on a fringing coral reef lagoon
along the southern Pacific island of Rarotonga over a tidal and diel cycle.
Benthic alkalinity fluxes were affected by the advective circulation of water
through permeable sediments, with net daily flux rates of carbonate
alkalinity ranging from −1.55 to 7.76 mmol m−2 d−1, depending
on the advection rate. Submarine groundwater discharge (SGD) was a source of
TA to the lagoon, with the highest flux rates measured at low tide, and an
average daily TA flux of 1080 mmol m−2 d−1 at the sampling site.
Both sources of TA were important on a reef-wide basis, although SGD acted
solely as a delivery mechanism of TA to the lagoon, while porewater advection
was either a sink or source of TA dependent on the time of day. This study
describes overlooked sources of TA to coral reef ecosystems that can
potentially alter water column carbonate chemistry. We suggest that porewater
and groundwater fluxes of TA should be taken into account in ocean
acidification models in order to properly address changing carbonate
chemistry within coral reef ecosystems. |
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