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Concentrations and fractionation of carbon, iron, sulfur, nitrogen and phosphorus in mangrove sediments along an intertidal gradient (semi-arid climate, New Caledonia) ArchiMer
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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Divergent biophysical controls of aquatic CO2 and CH4 in the World's two largest rivers ArchiMer
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...
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Ano: 2015 URL: https://archimer.ifremer.fr/doc/00603/71528/69955.pdf
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Effects of seasonal dynamics in a Zostera noltii meadow on phosphorus and iron cycles in a tidal mudflat (Arcachon Bay, France) ArchiMer
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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Seasonal Pattern of the Biogeochemical Properties of Mangrove Sediments Receiving Shrimp Farm Effluents (New Caledonia) ArchiMer
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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Thermal enhancement of gas transfer velocity of CO2 in an Amazon floodplain lake revealed by eddy covariance measurements ArchiMer
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...
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Ano: 2013 URL: https://archimer.ifremer.fr/doc/00603/71532/69950.pdf
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