Water column distribution and carbon isotopic signal of cholesterol, brassicasterol and particulate organic carbon in the Atlantic sector of the Southern Ocean

• Published in: Biogeosciences
• Main Authors: Cavagna, Anne-Julie, Dehairs, Frank, Bouillon, Steven, Woule-Ebongué, V., Planchon, Frédéric, Delille, Bruno, Bouloubassi, Ioanna
• Other Authors: Analytical and Environmental Chemistry and Earth System Sciences, Vrije Universiteit Brussel (VUB), Department of Earth and Environmental Sciences Leuven (EES), Catholic University of Leuven = Katholieke Universiteit Leuven (KU Leuven), Department of Geology and Mineralogy, Royal Museum for Central Africa Tervuren (RMCA), Laboratoire des Sciences de l'Environnement Marin (LEMAR) (LEMAR), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Institut Universitaire Européen de la Mer (IUEM), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Département d'astrophysique, Géophysique et Océanographie (AGO), Université de Liège, Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Thisresearch was supported by the European Network of Excellence forOcean Ecosystems Analysis, through a Ph.D. grant to A.-J. Cav-agna (EUR-OCEANS FP6 contract 511106), the Federal BelgianScience Policy Office (BELSPO) under the Science for Sustainable Development (SDD) program (Integrated Study of Southern OceanBiogeochemistry and Climate Interaction in the AnthropoceneBELCANTO contracts EV/37/7C, EV/03/7A, SD/CA/03A) andthe FWO project G.0220.10, BONUS-GoodHope, European Project: 511106,EUR-OCEANS NoE
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; Southern Ocean; Weddell; ice algae; Sea ice
• Online Access: https://hal.science/hal-00914348; https://hal.science/hal-00914348v2/document; https://hal.science/hal-00914348v2/file/bg-10-2787-2013.pdf; https://doi.org/10.5194/bg-10-2787-2013

Titre original dans Biogeosciences Discussions : Whole water column distribution and carbon isotopic composition of bulk particulate organic carbon, cholesterol and brassicasterol from the Cape Basin to the northern Weddell Gyre in the Southern Ocean (DOI : 10.5194/BGD-9-1667-2012) International audience The combination of concentrations and δ 13 C signatures of Particulate Organic Carbon (POC) and sterols provides a powerful approach to study ecological and environmental changes both in the modern and ancient ocean, but its application has so far been restricted to the surface area. We applied this tool to study the biogeochemical changes in the modern ocean water column during the BONUS-GoodHope survey (Feb-Mar 2008) from Cape Basin to the northern part of the Weddell Gyre. Cholesterol and brassicasterol were chosen as ideal biomarkers of the heterotrophic and autotrophic carbon pools, respectively, because of their ubiquitous and relatively refractory nature. We document depth distributions of concentrations (relative to bulk POC) and δ 13 C signatures of cholesterol and brassicasterol from the Cape Basin to the northern Weddell Gyre combined with CO 2 aq. surface concentration variation. While relationships between surface water CO 2 aq. and δ 13 C of bulk POC and biomarkers have been previously established for surface waters, our data show that these remain valid in deeper waters, suggesting that δ 13 C signatures of certain biomarkers could be developed as proxies for surface water CO 2 aq. Our data suggest a key role of zooplankton fecal aggregates in carbon export for this part of the Southern Ocean. We observed a general increase in sterol δ 13 C signatures with depth, which is likely related to a combination of particle size effects, selective feeding on larger cells by zooplankton, and growth rate related effects Additionally, in the southern part of the transect south of the Polar Front (PF), the release of sea-ice algae is hypothesized to influence the isotopic signature of sterols in the open ...