Early winter barium excess in the southern Indian Ocean as an annual remineralisation proxy (GEOTRACES GIPr07 cruise) ...

• Main Authors: van Horsten, Natasha René, Planquette, Hélène, Sarthou, Géraldine, Ryan-Keogh, Thomas James, Lemaitre, Nolwenn, Mtshali, Thato Nicholas, Roychoudhury, Alakendra, Bucciarelli, Eva
• Format: Article in Journal/Newspaper
• Language: English
• Published: ETH Zurich 2022
• Subjects: Southern Ocean
• Online Access: https://dx.doi.org/10.3929/ethz-b-000558288; http://hdl.handle.net/20.500.11850/558288

The Southern Ocean (SO) is of global importance to the carbon cycle, and processes such as mesopelagic remineralisation that impact the efficiency of the biological carbon pump in this region need to be better constrained. During this study early austral winter barium excess (Baxs) concentrations were measured for the first time, along 30° E in the southern Indian Ocean. Winter Baxs concentrations of 59 to 684 pmol L−1 were comparable to those observed throughout other seasons. The expected decline of the mesopelagic Baxs signal to background values during winter was not observed, supporting the hypothesis that this remineralisation proxy likely has a longer timescale than previously reported. A compilation of available SO mesopelagic Baxs data, including data from this study, shows an accumulation rate of ∼0.9 µmol m−2 d−1 from September to July that correlates with temporally integrated remotely sensed primary productivity (PP) throughout the SO from data spanning ∼20 years, advocating for a possible ... : Biogeosciences, 19 (13) ...