Temporal variability of lagoon-sea water exchange and seawater circulation through a Mediterranean barrier beach
Tamborski, Joseph (Observatoire Midi Pyrénées)
van Beek, Pieter (Observatoire Midi Pyrénées)
Rodellas, Valentí (Aix-Marseille Université)
Monnin, Christophe (Observatoire Midi Pyrénées)
Bergsma, Erwin (Observatoire Midi Pyrénées)
Stieglitz, Thomas C. (Aix-Marseille University)
Heilbrun, Christina (Stony Brook University)
Cochran, J. Kirk (Stony Brook University)
Charbonnier, Céline (Université de Bordeaux)
Anschutz, Pierre (Université de Bordeaux)
Bejannin, Simon (Observatoire Midi Pyrénées)
Beck, Aaron (Helmholtz Centre for Ocean Research Kiel)

Data:	2019
Resum:	The subterranean flow of water through sand barriers between coastal lagoons and the sea, driven by a positive hydraulic gradient, is a net new pathway for solute transfer to the sea. On the sea side of sand barriers, seawater circulation in the swash-zone generates a flux of recycled and new solutes. The significance and temporal variability of these vectors to the French Mediterranean Sea is unknown, despite lagoons constituting ~ 50% of the coastline. A one-dimensional 224Raex/223Ra reactive-transport model was used to quantify water flow between a coastal lagoon (La Palme) and the sea over a 6-month period. Horizontal flow between the lagoon and sea decreased from ~ 85 cm d-1 during May 2017 (0. 3 m3 d-1 m-1 of shoreline) to ~ 20 cm d-1 in July and was negligible in the summer months thereafter due to a decreasing hydraulic gradient. Seawater circulation in the swash-zone varied from 10 to 52 cm d-1 (0. 4-2. 1 m3 d-1 m-1), driven by short-term changes in the prevailing wind and wave regimes. Both flow paths supply minor dissolved silica fluxes on the order of ~ 3-10 mmol Si d-1 m-1. Lagoon-sea water exchange supplies a net dissolved inorganic carbon (DIC) flux (320-1100 mmol C d-1 m-1) two orders of magnitude greater than seawater circulation and may impact coastal ocean acidification. The subterranean flow of water through sand barriers represents a significant source of new DIC, and potentially other solutes, to the Mediterranean Sea during high lagoon water-level periods and should be considered in seasonal element budgets.
Ajuts:	European Commission 748896
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Publicat a:	Limnology and Oceanography, Vol. 64, Issue 5 (April 2019) , p. 2059-2080, ISSN 1939-5590

DOI: 10.1002/lno.11169

22 p, 2.5 MB

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