Gévaudan M. auteur aut IRD Jouanno Julien auteur aut IRD Aumont Olivier auteur aut IRD Boutin J. auteur aut IRD text journalArticle eng text/pdf born digital access The Amazon River is an important freshwater and nutrient source for the tropical Atlantic Ocean, sustaining large phytoplankton blooms that extend hundreds of kilometers from the river mouth. However, the main drivers of the productivity in the Amazon plume are still poorly understood. To address this question, a regional coupled ocean-biogeochemical configuration of the tropical Atlantic at 1/4 degrees is used, as well as remote sensing observations of sea surface salinity and ocean color, which allow an improved model treatment of the organic matter of riverine origin. Results reveal that the offshore extension of the productive plume is mainly driven by the large fluxes of terrestrial dissolved organic matter (TDOM) supplied by the Amazon River. Two mechanisms by which TDOM influences plume extension have been identified. First, the colored fraction limits the light available for phytoplankton growth, thereby delaying nutrient consumption. Second, TDOM supplied by rivers has low lability and is therefore slowly remineralized, providing nutrients throughout the plume until far offshore. The inclusion of these two effects (shading and specific remineralization of TDOM) in the model allows for a better representation of Amazon plume productivity and offshore extension, something that is generally lacking in regional or global biogeochemical models. specialized Amazon River river plume terrestrial dissolved organic matter NEMO-PISCES ATLANTIQUE AMAZONE COURS D'EAU ZONE TROPICALE 032 036 020 130 5 e2024JC021527 [18 p.] 2025 2169-9275 https://www.documentation.ird.fr/hor/fdi:010093554 10.1029/2024jc021527 2169-9275 [F B010093554] https://www.documentation.ird.fr/hor/fdi:010093554 https://www.documentation.ird.fr/intranet/publi/2025-06/010093554.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2025-06-11 2025-11-04 fdi:010093554 fre