Éditeur(s) : Amer Geophysical Union
Résumé : The freshest surface waters in the tropical Pacific are found at its eastern boundary. Using in situ observations, we depict the quasi-permanent presence of a far eastern Pacific fresh pool with Sea Surface Salinity (SSS) lower than 33, which is confined between Panama's west coast and 85W in December and extends westward to 95W in April. Strong SSS fronts are found at the outer edge of this fresh pool. We investigate the seasonal dynamics of the fresh pool using complementary satellite wind, rain, sea level and in situ oceanic current data at the surface, along with hydrographic profiles. The fresh pool appears off Panama due to the strong summer rains associated with the northward migration of the ITCZ over Central America in June. During the second half of the year, the eastward-flowing North Equatorial Counter Current keeps it trapped to the coast and strengthens the SSS front on its western edge. During winter, as the ITCZ moves southward, the north-easterly Panama gap wind creates a south-westward jet-like current in its path with a dipole of Ekman pumping/eddies on its flanks. As a result, upwelling in the Panama Bight brings to the surface cold and salty waters which erode the fresh pool on its eastern side while both the jet current and the enhanced South Equatorial Current stretch the fresh pool westward until it nearly disappears in May. New SMOS satellite SSS data proves able to capture the main seasonal features of the fresh pool and monitor its spatial extent.
Journal Of Geophysical Research-oceans (0148-0227) (Amer Geophysical Union), 2012-04 , Vol. 117 , P. -

Droits : 2012 AGU
http://archimer.ifremer.fr/doc/00072/18311/16581.pdf
DOI:10.1029/2011JC007802
http://archimer.ifremer.fr/doc/00072/18311/

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Abstract View references (35)La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) hollow fibres were prepared by a phase inversion/sintering method using polyetherimide as a binder. In order to overcome surface exchange kinetics limitation, LSCF hollow fibres were coated with ∼200nm palladium (Pd) nanoparticles. The O2 flux of best performing membranes increased by up to 350% in comparison to unmodified LSCF hollow fibres. Optimal enhancement was achieved with a single Pd coating. Additional coatings resulted in reduced O2 fluxes, thus counter acting the beneficial spill-over effect of the catalyst. Long term stability testing in atmospheric air at 850°C showed that a LSCF membrane modified with a single Pd coating continually outperformed a pure LSCF hollow fibre for over 400h, though the level of enhancement was reduced over time. A dramatic reduction in performance of more than 45% occurred within the first 24h of testing, which was attributed to the coalescence and aggregation of Pd catalyst particles to ∼1000nm size at the LSCF grain boundaries. This greatly reduced the available area for the oxygen species to spill-over onto the LSCF surface and thus reduced the overall O2 flux. © 2011 Elsevier B.V.
ISSN: 0376-7388

hal-01683196
https://hal.univ-antilles.fr/hal-01683196
DOI : 10.1016/j.memsci.2011.07.008

Éditeur(s) : HAL CCSD World Scientific
Résumé : The present paper presents a laboratory experiment of rip current circulations over a moveable bed. The rip current characteristics over four distinct beach morphologies, exhibiting more or less developed nature-like bar-rip morphology,were investigated. For each video run, the same off shore shore-normal waves were generated by the wave maker with the same mean water level in order to study the sensitivity of the rip current characteristics as a function of the beach morphology only. In each case, a 1-hour video run was used to track a large number (~30) of drifters released within the surf zone. Image coordinates were then rectifie d to still water level Cartesian coordinates to compute drifter velocities, mean characteristics and surf zone rete ntion rates. Results show the presence of classic rip current patterns with counter-rotating cells and a relatively narrowoffshore-directed jet with, for three of the situations, a reasonably symmetric shape. Non-surprisingly, it was found that rip current intensity increases with increasing relative depth of the rip channel. The wave-driven circulations were strongly unstable. Computed standard deviation in fl ow intensity and direction provides high resolution information on the spatial variability of the rip current insta bilities with, for instance, highly-pulsating and weakly directionally variable offshore-directed flow in the rip channel. Conversely to what was previously hypothesized in the literature, there was hardly trace of vortices being shed offs hore and drifters exiting the surf zone compartment were not systematically caught by a pulsating jet. The cause for drifter exiting the semi-enclosed surf zone compartment remains, however, elusive and deserves further investigations. The computed surf zone retention rates (~90%) were of the order of those previously observed in the field, with no clear relationship with the mean rip current velocity or relative depth of the rip channel. Further video-runs will have to be analyzed to explore potential explanations
Proceedings of Coastal Dynamics 2009 Impacts of Human Activities on Dynamic Coastal Processes

ISBN : 978-981-4282-46
hal-00854534
https://hal.archives-ouvertes.fr/hal-00854534

Éditeur(s) : HAL CCSD
Résumé : International audience
Paracetamol and NSAIDs, in particular acetylsalicylic acid (aspirin) and ibuprofen, are among the most used and environmentally released pharmaceutical drugs. The differences in international trends in the sale and consumption of mild analgesics reflect differences in marketing, governmental policies, habits, accessibility, disease patterns and the age distribution of each population. Biomonitoring indicates ubiquitous and high human exposure to paracetamol and to salicylic acid, which is the main metabolite of acetylsalicylic acid. Furthermore, evidence suggests that analgesics can have endocrine disruptive properties capable of altering animal and human reproductive function from fetal life to adulthood in both sexes. Medical and public awareness about these health concerns should be increased, particularly among pregnant women.
Nature Reviews Endocrinology

hal-01359566
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01359566
DOI : 10.1038/nrendo.2016.55
PUBMED : 27150289