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| Deborde, Jonathan; Abrill, Gwenael; Mouret, Aurelia; Jezequel, Didier; Thouzeau, Gerard; Clavier, Jacques; Bachelet, Guy; Anschutz, Pierre. |
| A study was conducted in Arcachon Bay, France, to determine the effect of seasonal dynamics in a Zostera noltii meadow on P and Fe cycles in the superficial sediments of a tidal mudflat. The redox-sensitive Fe particulate pool and associated P in the root zone showed a seasonal variation following the growth and decay of Z. noltii biomass, with a maximum content during the growth period. In comparison, the bare sediments did not show significant seasonal changes. A dissolved inorganic phosphorus (DIP) uptake was measured from the water column to the sediment in vegetated sediments, whereas a net DIP efflux was observed in the unvegetated sediments. During the growth period, the formation of an iron oxihydroxide-rich zone occurred and acted as a trap for... |
| Tipo: Text |
Palavras-chave: Nutrient; Eelgrass growth; Intertidal zone; Lagoon; Early diagenesis. |
| Ano: 2008 |
URL: https://archimer.ifremer.fr/doc/00603/71539/69966.pdf |
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| Anschutz, Pierre; Deborde, Jonathan. |
| The speciation of Phosphorus (P) in geologic materials can inform diverse investigations in such as aquatic biogeochemistry, soil sciences, and paleo-oceanography. Here, we describe in detail a set of sequential extraction schemes to measure P concentrations from several operationally defined phases: pore water, exchangeable or loosely sorbed P, Fe-bound P, P associated with biogenic apatite, P associated with authigenic apatite and carbonate forms, P associated with detrital apatite and inorganic forms, and organic P. The two benefits of the procedures we describe compared to prior methodological studies are: (1) fast, simple and inexpensive colorimetric methods have been developed for P determination in all the different matrices; and (2) the Fe-bound... |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00375/48616/49431.pdf |
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| Polsenaere, Pierre; Deborde, Jonathan; Detandt, Guillaume; Vidal, Luciana O.; Perez, Marcela A. P.; Marieu, Vincent; Abril, Gwenael. |
| In November 2011, the partial pressures of carbon dioxide (pCO(2)) in water and air in a floodplain lake of the Amazon River in Brazil were 800 +/- 75 and 387 +/- 8 ppmv, respectively. Turbulent CO2 fluxes from the lake measured with eddy covariance ranged from 0.05 to 2.2 mmol m(-2) s(-1). The corresponding gas transfer velocities k(600) ranged from 1.3 to 31.6 cm h(-1), averaging 12.2 +/- 6.7 cm h(-1). At moderate to high wind speed, k(600) increased with wind speed, with values above parameterizations for other lake ecosystems. During the prevailing tropical low wind speed (below 2.7 m s(-1)) and high insolation conditions, unexpected high k(600) values (up to 20 cm h(-1)) were obtained and correlated with latent heat and sensible heat fluxes. In... |
| Tipo: Text |
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| Ano: 2013 |
URL: https://archimer.ifremer.fr/doc/00603/71532/69950.pdf |
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| Borges, Alberto V.; Abril, Gwenael; Darchambeau, Francois; Teodoru, Cristian R.; Deborde, Jonathan; Vidal, Luciana O.; Lambert, Thibault; Bouillon, Steven. |
| Carbon emissions to the atmosphere from inland waters are globally significant and mainly occur at tropical latitudes. However, processes controlling the intensity of CO2 and CH4 emissions from tropical inland waters remain poorly understood. Here, we report a data-set of concurrent measurements of the partial pressure of CO2 (pCO(2)) and dissolved CH4 concentrations in the Amazon (n = 136) and the Congo (n = 280) Rivers. The pCO(2) values in the Amazon mainstem were significantly higher than in the Congo, contrasting with CH4 concentrations that were higher in the Congo than in the Amazon. Large-scale patterns in pCO(2) across different lowland tropical basins can be apprehended with a relatively simple statistical model related to the extent of wetlands... |
| Tipo: Text |
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| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00603/71528/69955.pdf |
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| Deborde, Jonathan; Anschutz, Pierre; Chaillou, Gwenaelle; Etcheber, Henri; Commarieu, Marc-vincent; Lecroart, Pascal; Abril, Gwenael. |
| Suspended particles and surface waters were collected in the Gironde estuary (southwestern France) along the salinity gradient. Dissolved inorganic phosphorus (DIP) was analyzed in the filtered surface waters. The suspended particles were sequentially leached to determine five fractions of phosphorus: exchangeable or loosely sorbed P, reactive Fe-bound P, refractory Fe oxide-bound P, P associated with apatite and carbonates, and organic P. Experiments were conducted to determine the effects of temperature, salinity, and DIP concentration on phosphorus sorption/desorption processes. The concentration and distribution of particulate phosphorus was homogeneous along the salinity gradient of the estuary, whereas it was variable in time and space in the... |
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| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00603/71538/69943.pdf |
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| Deborde, Jonathan; Marchand, Cyril; Molnar, Nathalie; Della Patrona, Luc; Meziane, Tarik. |
| In mangrove ecosystems, strong reciprocal interactions exist between plant and substrate. Under semi-arid climate, Rhizophora spp. are usually predominant, colonizing the seashore, and Avicennia marina develops at the edge of salt-flats, which is the highest zone in the intertidal range. Along this zonation, distribution and speciation of C, Fe, S, N, and P in sediments and pore-waters were investigated. From the land-side to the sea-side of the mangrove, sediments were characterized by I/ increase in: (i) water content; (ii) TOC; (iii) mangrove-derived OM; II/ and decrease in: (i) salinity; (ii) redox; (iii) pH; (iv) solid Fe and solid P. Beneath Avicennia and Rhizophora, TS accumulated at depth, probably as a result of reduction of iron oxides and... |
| Tipo: Text |
Palavras-chave: Mangrove; Zonation; Biogeochemistry; New Caledonia. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00251/36252/34802.pdf |
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| Marchand, Cyril; Molnar, N.; Deborde, Jonathan; Della Patrona, Luc; Meziane, Tarik. |
| Coastal tropical shrimp farming may impact the adjacent ecosystems through the release of large quantities of effluents rich in nutrients. In New Caledonia, mangroves are considered as a natural biofilter to reduce impacts on the surrounding World Heritage listed lagoon. Our main objective was to understand the influence of effluent discharge on the biogeochemistry of mangrove sediments. A monitoring of the physico-chemical parameters of mangrove sediments was carried out during a whole year, including active and non active periods of the farm. The parameters studied were: i) benthic primary production (Chl-a concentrations), ii) physico-chemical parameters of sediments (redox potential, pH, salinity, TOC, TN, TS, δ13C and δ15N), iii) concentrations of... |
| Tipo: Text |
Palavras-chave: Shrimp farming; Effluents; Mangrove; Sediment biogeochemistry; New Caledonia. |
| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00251/36253/34801.pdf |
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