Éditeur(s) : HAL CCSD Royal Society of Chemistry
Résumé : International audience
A series of graphene oxide (GO) and zinc partially substituted magnetite GO-Fe1-xZnxOy (0 ≤ x ≤ 0.285) catalysts were synthesised through a precipitation-oxidation method. The rate constants for the degradation of acid orange seven (AO7) proceeded at a significant faster rate under UV-irradiation (up to 670%) than the conventional heterogeneous Fenton-like reaction. The resultant catalysts were mesoporous, so there was no mass transfer limitation for AO7 to access active sites in the catalysts. Further, maximum increases of rate constant up to 220% occurred as the zinc molar concentration increased from x = 0 to x = 0.159. GO enhanced to incorporation of zinc into the combined metal oxide, whilst zinc limited crystal growth, thus forming smaller crystallite sizes. These features proved to be essential for the improved catalytic activity of the resultant catalysts. The optimised zinc molar value at x = 0.159 delivered the best catalytic activity. © The Royal Society of Chemistry 2016.
ISSN: 2046-2069

hal-01683215
https://hal.univ-antilles.fr/hal-01683215
DOI : 10.1039/c6ra04068c

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
The extent to which Marine Protected Areas (MPAs) benefit corals is contentious. On one hand, MPAs could enhance coral growth and survival through increases in herbivory within their borders; on the other, they are unlikely to prevent disturbances, such as terrestrial runoff , that originate outside their boundaries. We examined the effect of spatial protection and terrestrial sediment on the benthic composition of coral reefs in Saint Lucia. In 2011 (10 to 16 years after MPAs were created), we resurveyed 21 reefs that had been surveyed in 2001 and analyzed current benthic assemblages as well as changes in benthic cover over that decade in relation to protection status, terrestrial sediment influence (measured as the proportion of terrigenous material in reef-associated sediment) and depth. The cover of all ben-thic biotic components has changed significantly over the decade, including a decline in coral and increase in macroalgae. Protection status was not a significant predictor of either current benthic composition or changes in composition, but current cover and change in cover of several components were related to terrigenous content of sediment deposited recently. Sites with a higher proportion of terrigenous sediment had lower current coral cover, higher macroalgal cover and greater coral declines. Our results suggest that terrestrial sediment is an important factor in the recent degradation of coral reefs in Saint Lucia and that the current MPA network should be complemented by measures to reduce runoff from land.
ISSN: 1932-6203

hal-01281152
https://hal-univ-perp.archives-ouvertes.fr/hal-01281152
https://hal-univ-perp.archives-ouvertes.fr/hal-01281152/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01281152/file/journal.pone.0146855.PDF
DOI : 10.1371/journal.pone.0146855