On the barium-oxygen consumption relationship in the Mediterranean Sea: implications for mesopelagic marine snow remineralisation

• Main Authors: Jacquet, Stéphanie, Lefèvre, Dominique, Tamburini, Christian, Garel, Marc, Le Moigne, Frédéric A.C., Bhairy, Nagib, Roumagnac, Marie, Guasco, Sophie
• Other Authors: Institut méditerranéen d'océanologie (MIO), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Toulon (UTLN)-Centre National de la Recherche Scientifique (CNRS)
• Format: Report
• Language: English
• Published: HAL CCSD 2020
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; Southern Ocean
• Online Access: https://hal.science/hal-02960676; https://doi.org/10.5194/bg-2020-241

Abstract. In the ocean, remineralisation rate associated with sinking particles is a crucial variable. Since the 90's, particulate biogenic barium (Baxs) has been used as an indicator of carbon remineralization by applying a transfer function relating Baxs to O2 consumption (Dehairs's transfer function, Southern Ocean-based). Here, we tested its validity in the Mediterranean Sea (ANTARES / EMSO-LO) for the first time by investigating connections between Baxs, prokaryotic heterotrophic production (PHP) and oxygen consumption (JO2-Opt; optodes measurement). We show that: (1) higher Baxs (409 pM; 100–500 m) in situations where integrated PHP (PHP100/500 = 0.90) is located deeper, (2) higher Baxs with increasing JO2-Opt, and (3) similar magnitude between JO2-Opt (3.14 mmol m−2 d−1; 175–450 m) and JO2-Ba (4.59 mmol m−2 d−1; transfer function). Overall, Baxs, PHP and JO2 relationships follow trends observed in the Southern Ocean. We believe that such transfer function could apply in the Mediterranean Sea with no restriction.