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| Titel |
Submarine groundwater discharge to a small estuary estimated from radon and salinity measurements and a box model |
| VerfasserIn |
J. Crusius, D. Koopmans, J. F. Bratton, M. A. Charette, K. Kroeger, P. Henderson, L. Ryckman, K. Halloran, J. A. Colman |
| 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 ; 2, no. 2 ; Nr. 2, no. 2 (2005-06-24), S.141-157 |
| Datensatznummer |
250000489
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| Publikation (Nr.) |
 copernicus.org/bg-2-141-2005.pdf |
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| Zusammenfassung |
| Submarine groundwater discharge was quantified by a variety of methods for a
4-day period during the early summer of 2004, in Salt Pond, adjacent to
Nauset Marsh, on Cape Cod, USA. Discharge estimates based on radon and
salinity took advantage of the presence of the narrow channel connecting
Salt Pond to Nauset Marsh, which allowed constructing whole-pond mass
balances as water flowed in and out due to tidal fluctuations. The data
suggest that less than one quarter of the discharge in the vicinity of Salt
Pond happened within the pond itself, while three quarters or more of the
discharge occurred immediately seaward of the pond, either in the channel or
in adjacent regions of Nauset Marsh. Much of this discharge, which maintains
high radon activities and low salinity, is carried into the pond during each
incoming tide. A box model was used as an aid to understand both the rates
and the locations of discharge in the vicinity of Salt Pond. The model
achieves a reasonable fit to both the salinity and radon data assuming
submarine groundwater discharge is fresh and that most of it occurs either
in the channel or in adjacent regions of Nauset Marsh. Salinity and radon
data, together with seepage meter results, do not rule out discharge of
saline groundwater, but suggest either that the saline discharge is at most
comparable in volume to the fresh discharge or that it is depleted in radon.
The estimated rate of fresh groundwater discharge in the vicinity of Salt
Pond is 3000-7000 m3 d-1. This groundwater flux estimated from the
radon and salinity data is comparable to a value of 3200-4500 m3
d-1 predicted by a recent hydrologic model (Masterson, 2004; Colman and
Masterson, 2004), although the model predicts this rate of discharge to the
pond whereas our data suggest most of the groundwater bypasses the pond
prior to discharge. Additional work is needed to determine if the measured
rate of discharge is representative of the long-term average, and to better
constrain the rate of groundwater discharge seaward of Salt Pond. |
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