TY - JOUR TI - Mangrove-Derived Organic and Inorganic Carbon Exchanges Between the Sinnamary Estuarine System (French Guiana, South America) and Atlantic Ocean AU - Ray, Raghab AU - Thouzeau, Gerard AU - Walcker, Romain AU - Vantrepotte, Vincent AU - Gleixner, Gerd AU - Morvan, Sylvain AU - Devesa, Jeremy AU - Michaud, Emma T2 - Journal of Geophysical Research-Biogeosciences AB - There is growing evidence that a substantial fraction of the dissolved organic and inorganic carbon (DOC and DIC) and particulate organic carbon (POC) can be exported from mangroves to the ocean. Yet our understanding of C fluxes in mangrove forests is limited to only few regional studies that exclude the world's longest sediment dispersal system connected to the Amazon River. The present study aims at (1) examining tidal fluctuations of DOC, POC, and DIC; their isotopes; and optical properties such as chromophoric dissolved organic matter (CDOM) and (2) estimating their exchange fluxes between the mangroves and adjacent coastal water in the Sinnamary estuary, French Guiana. Time series observation highlighted that physical processes coupled to tides controlled diel dynamics and sources of DOC (e.g., litter leaching and pore water seepage) and POC (microphytobenthos, sediment resuspension, and bioturbation activities). Intense benthic remineralization could account for high water column pCO(2) and DIC exchange flux during the low tide. Mangrove-derived DOC export to inner shelf (8.14 g C m(-2) day(-1)) was exceeding import of POC and DIC from the mud bank and marine sources to the mangroves (1.35 and 0.90 g C m(-2) day(-1), respectively). Because of specific dynamics of the Amazon mobile muds, local geomorphology, water column stratification, and environmental forcing, Guianese mangroves cannot be seen as simple C exporters to the Atlantic waters. These first data setting on C fluxes for the region should be included along with other studies to improve global mangrove C budget estimate. Key Points Dissolved and particulate carbon exchange fluxes were estimated in a mangrove dominated estuary, French Guiana coastal systems Mangroves are exporter of DOC and importer of DIC and POC that is contrast to previous simplification of mangrove-derived C export Distinctive sources of DOC, POC, and DIC were observed referring to specificity and dynamics of the Guianese coastal systems DA - 2020/08// PY - 2020 DO - 10.1029/2020JG005739 DP - Web of Science VL - 125 IS - 8 SP - e2020JG005739 J2 - J. Geophys. Res.-Biogeosci. LA - English SN - 2169-8953 UR - https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JG005739 KW - ACL KW - BIOMANGO: ANR-12-JSV7-0012-01 KW - CNRS KW - DISCOVERY KW - French Guiana KW - Labex CEBA: ANR-10-LABX-25-01 KW - LabexMER_ANR-10-LABX-0019 KW - Outremer KW - UBO KW - animal burrows KW - carbon flux KW - chibido KW - co2 KW - dynamics KW - gas transfer velocities KW - mangrove KW - mangroves KW - matter KW - mud bank KW - organic matter KW - rain-forest KW - tidal creek KW - tidal cycle KW - water KW - wind-speed ER -