FN Archimer Export Format
PT J
TI Gaining insight into Clipperton's lagoon hydrology using tritium
BT 
AF JEAN-BAPTISTE, Philippe
   FOURRE, Elise
   CHARLOU, Jean-Luc
   DONVAL, Jean-Pierre
   CORREGE, Thierry
AS 1:1;2:1;3:2;4:2;5:3;
FF 1:;2:;3:PDG-DOP-DCB-GM-LGM;4:PDG-DOP-DCB-GM-LGM;5:;
C1 CEA Saclay, LSCE, CEA CNRS IPSL, F-91191 Gif Sur Yvette, France.
   IFREMER, Ctr Brest, DRO GM, Plouzane, France.
   Univ Bordeaux 1, CNRS, UMR 5805, F-33405 Talence, France.
C2 CEA, FRANCE
   IFREMER, FRANCE
   UNIV BORDEAUX, FRANCE
SI BREST
SE PDG-DOP-DCB-GM-LGM
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 1.97
TC 5
UR https://archimer.ifremer.fr/doc/2009/publication-6457.pdf
LA English
DT Article
DE ;Oxygen isotopes;Tritium;Enclosed lagoon hydrology;Clipperton atoll
AB Historical descriptions of the Clipperton lagoon appear to converge on the fact that it became isolated from the surrounding ocean around 1858. Since then, because of the high precipitation rate which largely exceeds evaporation in this region of the eastern tropical Pacific, a brackish lens has formed on top of the saline oceanic waters. In 1980, literature data show that the thickness of this water body was reaching 14 m. During the 2005 Etienne's Clipperton expedition, we collected lagoon water on two vertical profiles. Salinity, delta O-18 and tritium analyses were performed on these samples with the objective of gaining further insight into the lagoon hydrology and age of the deep waters. The upper 15 m were characterized by low salinities (5.4 +/- 0.2), and delta O-18 and tritium values typical of local precipitation. At depth, waters had salinity and delta O-18 similar to oceanic surface waters but with low tritium concentrations, hence pointing to quite isolated waters representing a remnant of marine waters when the lagoon was still communicating with the ocean. At lagoon closure, the excess of precipitation over evaporation raised the lagoon level, thus creating a hydraulic pressure head which favored salt expulsion through the permeable walls of the atoll. A simple geohydrological modeling of this salt expulsion process based on Darcy's law describes reasonably well the time-evolution of the brackish lens. Tritium is used to discuss the main physical processes potentially involved in the slow ventilation of the halocline and deep saline layer, including vertical diffusion, sinking of salty Surface water intrusions and deep horizontal exchange through fissures in the limestone. These different mechanisms give reasonable results, which are all compatible with available salinity and isotopic data (delta O-18 and tritium), and therefore are all plausible candidates. Unfortunately, the lack of a detailed description of the vertical tritium profile in the halocline, between -15 m and -20 m, precludes any further quantification of their respective role in the ventilation process. (C) 2009 Elsevier Ltd. All rights reserved.
PY 2009
PD JUL
SO Estuarine, Coastal and Shelf Science
SN 0272-7714
PU Elsevier
VL 83
IS 1
UT 000266540000005
BP 39
EP 46
DI 10.1016/j.ecss.2009.03.017
ID 6457
ER

EF