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See detailDissolved inorganic carbon dynamics and air-sea carbon dioxide fluxes during coccolithophore blooms in the northwest European continental margin (northern Bay of Biscay)
Suykens, Kim; Delille, Bruno ULg; Chou, Lei et al

in Global Biogeochemical Cycles (2010), 24

We report a data set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of the ... [more ▼]

We report a data set of dissolved inorganic carbon (DIC) obtained during three cruises in the northern Bay of Biscay carried out in June 2006, May 2007, and May 2008. During these cruises, blooms of the coccolithophore Emiliania huxleyi occurred, as indicated by patches of high reflectance on remote sensing images, phytoplankton pigment signatures, and microscopic examinations. Total alkalinity showed a nonconservative behavior as a function of salinity due to the cumulative effect of net community calcification (NCC) on seawater carbonate chemistry during bloom development. The cumulative effect of NCC and net community production (NCP) on DIC and the partial pressure of CO2 (pCO(2)) were evaluated. The decrease of DIC (and increase of pCO(2)) due to NCC was overwhelmingly lower than the decrease of DIC (and decrease of pCO(2)) due to NCP (NCC: NCP << 1). During the cruises, the northern Bay of Biscay acted as a sink of atmospheric CO2 (on average similar to-9.7 mmol C m(-2) d(-1) for the three cruises). The overall effect of NCC in decreasing the CO2 sink during the cruises was low (on average similar to 12% of total air-sea CO2 flux). If this is a general feature in naturally occurring phytoplankton blooms in the North Atlantic Ocean (where blooms of coccolithophores are the most intense and recurrent), and in the global ocean, then the potential feedback on increasing atmospheric CO2 of the projected decrease of pelagic calcification due to thermodynamic CO2 "production" from calcification is probably minor compared to potential feedbacks related to changes of NCP. [less ▲]

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See detailSeasonal variability of methane in the rivers and lagoons of Ivory Coast (West Africa)
Kone, Y. J. M.; Abril, G.; Delille, Bruno ULg et al

in Biogeochemistry (2010), 100(1-3), 21-37

We report a data-set of dissolved methane (CH4) in three rivers (Como,, Bia and Tano,) and five lagoons (Grand-Lahou, Ebri,, Potou, Aby and Tendo) of Ivory Coast (West Africa), during the four main ... [more ▼]

We report a data-set of dissolved methane (CH4) in three rivers (Como,, Bia and Tano,) and five lagoons (Grand-Lahou, Ebri,, Potou, Aby and Tendo) of Ivory Coast (West Africa), during the four main climatic seasons (high dry season, high rainy season, low dry season and low rainy season). The surface waters of the three rivers were over-saturated in CH4 with respect to atmospheric equilibrium (2221-38719%), and the seasonal variability of CH4 seemed to be largely controlled by dilution during the flooding period. The strong correlation of CH4 concentrations with the partial pressure of CO2 (pCO(2)) and dissolved silicate (DSi) confirm the dominance of a continental sources (from soils) for both CO2 and CH4 in these rivers. Diffusive air-water CH4 fluxes ranged between 25 and 1187 mu mol m(-2) day(-1), and annual integrated values were 288 +/- A 107, 155 +/- A 38, and 241 +/- A 91 mu mol m(-2) day(-1) in the Como,, Bia and Tano, rivers, respectively. In the five lagoons, surface waters were also over-saturated in CH4 (ranging from 1496 to 51843%). Diffusive air-water CH4 fluxes ranged between 20 and 2403 mu mol m(-2) day(-1), and annual integrated values were 78 +/- A 34, 338 +/- A 217, 227 +/- A 79, 330 +/- A 153 and 326 +/- A 181 mu mol m(-2) day(-1) in the Grand-Lahou, Ebri,, Potou, Aby and Tendo lagoons, respectively. The largest CH4 over-saturations were observed in the Tendo and Aby lagoons that are permanently stratified systems (unlike the other three lagoons), leading to anoxic bottom waters favorable for a large CH4 production. In addition, these two stratified lagoons showed low pCO(2) values due to high primary production, which suggests an efficient transfer of organic matter across the pycnocline. As a result, the stratified Tendo and Aby lagoons were respectively, a low source of CO2 to the atmosphere and a sink of atmospheric CO2 while the other three well-mixed lagoons were strong sources of CO2 to the atmosphere but less over-saturated in CH4. [less ▲]

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See detailDecadal changes of carbon dioxide in the Scheldt estuary
Borges, Alberto ULg; Middelburg, J. J.

Poster (2010)

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See detailCarbon dioxide and methane dynamics in estuaries
Borges, Alberto ULg; Abril, G.

Conference (2010)

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See detailEstimating pCO2 from remote sensing in the Belgian Coastal Zone
Borges, Alberto ULg; Ruddick, K.; Lacroix, G. et al

in ESA Living Planet Symposium : 28 June - 2 July 2010, Bergen, Norway (2010)

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See detailDecadal changes of carbon dioxide in the Scheldt estuary
Borges, Alberto ULg; Middelburg, J. J.

Poster (2010)

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See detailRole of pelagic calcification and export of carbonate production in climate change
Chou, Lei; Harlay, Jérôme ULg; De Bodt, Caroline et al

Poster (2009, November 16)

The marine carbon cycle constitutes a key component of the climate system. It has been shown that one-fourth of the anthropogenic CO2 emitted to the atmosphere is absorbed by the ocean, leading to the ... [more ▼]

The marine carbon cycle constitutes a key component of the climate system. It has been shown that one-fourth of the anthropogenic CO2 emitted to the atmosphere is absorbed by the ocean, leading to the acidification of the surface ocean and the modification of seawater carbonate chemistry. This could have major impacts on the ocean biogeochemical carbon cycling and ecosystem dynamics. Yet, the resulting feedbacks on climate change are still poorly understood. Interdisciplinary biogeochemical investigations, assisted by remote sensing, have been conducted during three consecutive years along the shelf break of the Northern Bay of Biscay where coccolithophorid blooms dominated by Emiliania huxleyi are frequently and recurrently observed. Rates of various processes governing the coccolithophore ecosystem dynamics have been determined and air-sea CO2 fluxes evaluated. The key results will be presented and discussed to evaluate the role in climate regulation of calcification, primary production and export processes during coccolithophorid blooms. [less ▲]

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See detailAir-ice CO2 fluxes and pCO2 dynamics in sea ice in the Arctic (Amundsen Gulf)
Geilfus, Nicolas-Xavier ULg; Tison, Jean Louis; Carnat, Gauthier et al

Conference (2009, November)

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See detailOceanic CO2 sink : the contribution of the marine cryosphere
Delille, Bruno ULg; Vancoppenolle, M.; Tilbrook, B. et al

Conference (2009, September)

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See detailSeasonal variability of carbon dioxide and methane in the rivers and lagoons of Ivory Coast (West Africa)
Koné, Y.J.M.; Abril, G.; Delille, Bruno ULg et al

Poster (2009, May)

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See detailAir-ice CO2 fluxes in the Arctic coastal area
Geilfus, Nicolas-Xavier ULg; Tison, Jean Louis; Carnat, Gauthier et al

Poster (2009, May)

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See detailBiogeochemistry and carbon budget during a coccolithophorid bloom in the northern Bay of Biscay (June 2006)
Harlay, Jérôme ULg; Borges, Alberto ULg; De Bodt, Caroline et al

Poster (2009, April 19)

Carbon cycling processes (primary production (PPp), calcification (CAL), bacterial production and pelagic community respiration (PCR)) and variables (partial pressure of CO2 (pCO2) and total alkalinity ... [more ▼]

Carbon cycling processes (primary production (PPp), calcification (CAL), bacterial production and pelagic community respiration (PCR)) and variables (partial pressure of CO2 (pCO2) and total alkalinity (TA)) were measured in early June 2006 at several stations in the northern Bay of Biscay. These measurements were characterized with respect to the coccolithophorid blooming (growth or decline) based on satellite remote sensing (high reflectance (HR)) and other biogeochemical measurements i.e. inorganic nutrients, chlorophyll-a (Chl-a), phaeopigments (Phaeo), particulate inorganic carbon (PIC), particulate organic carbon (POC) and particulate nitrogen (PN)). The major HR patch was located over the shelf, along the continental margin and corresponded to declining bloom conditions characterized by moderate Chl-a <1.0 µg L-1, dissolved phosphate (PO4) depletion, low (<2.0 µmol L-1) dissolved silicate (DSi), low potential primary production (<0.25 µmol C L-1 h-1) and calcification rates (0.02-0.10 µmol C L-1 h-1). Yet, surface waters were undersaturated in CO2 with respect to atmospheric equilibrium. We present a coherent scheme of the C dynamics of a coccolithophorid bloom along the continental margin of the Bay of Biscay, an active hydrodynamic area, based on standing stocks and processes including 14C-based particulate primary production, CAL and PCR. A carbon budget obtained by integrating PPp, CAL and PCR over the water column highlights the importance of C extracellular production to sustain the bacterial demand in the twilight zone, which has also several repercussions on the fate of organic and inorganic C production in the photic zone during the different stages of the bloom. [less ▲]

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