New insights on the mineralization of dissolved organic matter in central, intermediate, and deep water masses of the northeast North Atlantic

• Published in: Limnology and Oceanography
• Main Authors: Alvarez-Salgado, X. A., Nieto-Cid, M., Alvarez, M., Perez, F. F., Morin, Pascal, Mercier, H.
• Other Authors: Instituto de Investigaciones Marinas, Consejo Superior de Investigaciones Científicas Madrid (CSIC), Instituto Espanol de Oceanografia, Instituto Español de Oceanografía, Adaptation et diversité en milieu marin (AD2M), Station biologique de Roscoff Roscoff (SBR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Station biologique de Roscoff (SBR), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique des océans (LPO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2013
• Subjects: [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Arctic; Denmark Strait; North Atlantic
• Online Access: https://hal.archives-ouvertes.fr/hal-00836510; https://doi.org/10.4319/lo.2013.58.2.0681

International audience An optimum multiparameter (OMP) analysis was applied to samples collected during a cruise in the northeast North Atlantic with the aim of objectively defining water mass realms and calculating water mass mixingweighted average (archetypal) concentrations of dissolved organic carbon (DOC) and nitrogen (DON) and fluorescent dissolved organic matter (FDOM). The profile of archetypal DOC, which retains the basin-scale variability from the formation area of the water masses to the study area, was modeled with a constant initial concentration of 60 6 1 mmol kg21 that decreased linearly with increasing apparent oxygen utilization (AOU) at a rate of 20.20 6 0.03 mol C per mol of AOU. The archetypal C:N ratio of dissolved organic matter was also modeled with a constant initial molar ratio of 11.5 6 0.4 that increased at a rate of 0.06 6 0.01 per mmol kg21 of AOU. The profile of archetypal FDOM was modeled with a constant initial humic-like fluorescence of 0.54 6 0.07 quinine sulfate units that increased at a rate of 0.009 6 0.001 g equivalent of quinine sulphate per mol of AOU. Only the Denmark Strait Overflow Water departed from this behavior because of the marked terrestrial influence of Arctic rivers during the formation of this water mass. The variability not explained by the archetypal concentrations, which retain the local variability, suggesting that N-poor DOM was mineralized in the study area, and that the efficiency of the local production of humic-like substances was directly proportional to the ventilation of the corresponding water mass realms.