Éditeur(s) : Université des Antilles Le Carbet des Sciences
Extrait de : "Le théâtre des idées reçues" : conférence, le 17 novembre 2018. Palais des Congrès de Madiana
Description : Traditionnellement, et particulièrement lors des dernières épidémies de ZIKA et Chikungunya, les Martiniquais ont utilisé différentes méthodes pour chasser ou se protéger des moustiques : boucans, feuillages divers, tisanes, huiles essentielles, bracelets... Les moustiques faisant partie du « paysage martiniquais » et face à la possible survenue de nouvelles épidémies, il convient de faire le point sur l'efficacité de ces différentes méthodes lors de cette mini-conférence.

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V19026
V19026

Éditeur(s) : Université des Antilles AREBio Groupe de recherche BIOSPHERES : BIOlogie, Sciences Physiques & Humaines pour les énergies Renouvelables, l
Extrait de : 1er colloque international BIOSPHERES, du 18 au 20 juin 2019. Université des Antilles

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V19078
V19078

Éditeur(s) : Université des Antilles AREBio Groupe de recherche BIOSPHERES : BIOlogie, Sciences Physiques & Humaines pour les énergies Renouvelables, l
Extrait de : 1er colloque international BIOSPHERES, du 18 au 20 juin 2019. Université des Antilles
Description : La Martinique subit depuis quelques années une recrudescence de nuisance due aux piqûres de culicoïdes. Auparavant cantonnée aux zones littorales (plages, mangroves), cette nuisance s'est accentuée dans un passé récent, avec des attaques massives notifiées dans toute l'île, notamment à l'intérieur des terres. Si plus de 1300 espèces de ces petits moucherons hématophages membres de la famille des Ceratopogonidae sont inventoriées à l'échelle du globe, seules deux espèces avaient été décrites à la Martinique : Culicoides furens (Poey, 1853) et C. hoffmani (Fox, 1946). Cette communication nous en dit plus sur le sujet.

Droits : CC-BY-NC-ND - Attribution - Pas d'utilisation commerciale - Pas de modification
Permalien : http://www.manioc.org/fichiers/V19075
V19075

Éditeur(s) : HAL CCSD Mineralogical Society of America
Résumé : International audience
Wadsleyites with various iron contents were synthesized at ~12-14 GPa and 1400 °C under oxidizing and hydrous conditions in coexistence with enstatite. The samples were studied using micro-X-ray absorption near edge structure (XANES) and micro-Mössbauer spectroscopy to determine the ferric iron contents in polyphasic samples and secondary ion mass spectrometry (SIMS) to determine the water concentrations. XANES and Mössbauer analyses show that ferric iron content increases with increasing total iron content, and reaches a maximum of ~30% Fe3+/Fetotal. Two XANES results were cross-checked by Mössbauer analysis and both methods are in reasonable agreement. The use of Fourier transform infrared spectroscopy reveals a new protonation scheme in wadsleyite, with a significant proportion of protons associated with the high-frequency band at 3611 cm−1 and a new band located at 3500 cm−1. The intensity of these two bands is higher for Fe3+-rich wadsleyite. SIMS analyses show that water contents in wadsleyite vary from 4500 to 9400 ppm H2O by weight. Pyroxene water contents range from 790 to 1600 ppm wt H2O. The concentration of water in both phases decreases with increasing iron content. The partition coefficient of water between wadsleyite and pyroxene varies between 5 and 9 and increases with increasing Fe-number of wadsleyite [i.e., XFe/(XFe + XMg) × 100 ratio]. The divalent cation concentrations (i.e., Mg2+ + Fe2+), the Si as well as the H content in wadsleyite decrease with increasing Fe3+ content, indicating an incorporation mechanism via substitution into the metal (Me = Mg2+ and Fe2+) and Si sites with a ratio of 5/3 for (Fe3++H+):Me and of 5/1 for (Fe3++H+):Si, similarly as in the dry system. Thus, coupled substitution of Fe3+ and H+ does not affect the incorporation mechanism of Fe3+, but does affect the location of H+, which is partly incorporated at tetrahedral edges forming [FeSi′-(OH)o*]X neutral defects substituting for Si. In this model 25% of the ferric iron occupies the tetrahedral sites.
ISSN: 0003-004X

hal-00758071
https://hal.archives-ouvertes.fr/hal-00758071
DOI : 10.2138/am.2012.3869

Éditeur(s) : HAL CCSD Springer Verlag (Germany) Springer Verlag
Résumé : International audience
The Cerro del Almirez massif (Spain) represents a unique fragment of serpentinized oceanic lithosphere that has been first equilibrated in the antigorite stability field (Atg-serpentinites) and then dehydrated into chlorite–olivine–orthopyroxene (Chl-harzburgites) at eclogite facies conditions during subduction. The massif preserves a dehydration front between Atg-serpentinites and Chl-harzburgites. It constitutes a suitable place to study redox changes in serpentinites and the nature of the released fluids during their dehydration. Relative to abyssal serpentinites, Atg-serpentinites display a low Fe3+/FeTotal(BR) (=0.55) and magnetite modal content (=2.8–4.3 wt%). Micro-X-ray absorption near-edge structure (μ-XANES) spectroscopy measurements of serpentines at the Fe–K edge show that antigorite has a lower Fe3+/FeTotal ratio (=0.48) than oceanic lizardite/chrysotile assemblages. The onset of Atg-serpentinites dehydration is marked by the crystallization of a Fe3+-rich antigorite (Fe3+/FeTotal = 0.6–0.75) in equilibrium with secondary olivine and by a decrease in magnetite amount (=1.6–2.2 wt%). This suggests a preferential partitioning of Fe3+ into serpentine rather than into olivine. The Atg-breakdown is marked by a decrease in Fe3+/FeTotal(BR) (=0.34–0.41), the crystallization of Fe2+-rich phases and the quasi-disappearance of magnetite (=0.6–1.4 wt.%). The observation of Fe3+-rich hematite and ilmenite intergrowths suggests that the O2 released by the crystallization of Fe2+-rich phases could promote hematite crystallization and a subsequent increase in fo2 inside the portion of the subducted mantle. Serpentinite dehydration could thus produce highly oxidized fluids in subduction zones and contribute to the oxidization of the sub-arc mantle wedge.
ISSN: 0010-7999

hal-01172310
https://hal.archives-ouvertes.fr/hal-01172310
DOI : 10.1007/s00410-015-1130-y

Éditeur(s) : HAL CCSD Inter Research
Résumé : International audience
The main objective of the VULSACO (VULnerability of SAndy COasts to climate change and anthropic pressure) project was to investigate present day and potential future vulnerability of sandy coasts at the 2030 horizon, i.e. on a time scale related to climate variability. The method, based on a multidisciplinary approach bringing together geologists, geographers, physicists, social psychologists, engineers and stakeholders, was structured around 4 axes: field data analysis; numerical modelling; analysis of governance and stakeholder perceptions; and development of vulnerability indexes. This approach was designed to investigate vulnerability at a local scale and was applied to 4 contrasting beaches located in France: Sète Lido (Mediterranean Sea), Truc Vert and La Tresson beaches (Atlantic Ocean), and Dewulf (English Channel). The results focus on decadal and multi-annual beach trends at the Truc Vert beach site. There is almost no trend in beach volume at Truc Vert beach, although there is a variation in this parameter on a cycle of 2 to 3 yr, with variations related to wave energy and probably to indexes of climate variability. Numerical modelling identified the sensitivity of beach responses to changes in wave height and direction, especially in terms of subtidal morphology and the potential development of shoreline instability. Together with the observed offshore wave angle at the Biscay Buoy, these model results suggest that a potential change in wave angle due to climate variability could significantly modify the bars' morphology. The combination of data analysis and numerical modelling contributed to the development of vulnerability indexes designed for sandy coasts, which take into account climate-dependant variables such as waves. This allowed the differentiation of the sites in terms of vulnerability to erosion: Sète Lido and Truc Vert beach were the most and least vulnerable sites, respectively. These indexes help in identifying the dominant components of beach vulnerability, and provide potential for the study of how anthropogenic factors affect vulnerability. The study of stakeholder perceptions and decision-making with regard to climate-related risk also highlighted potential anthropogenic effects on beach vulnerability, and identified possible site-specific outcomes.
ISSN: 0936-577X

hal-00843946
https://hal-brgm.archives-ouvertes.fr/hal-00843946
DOI : 10.3354/cr01153