Atmospheric deposition fluxes over the Atlantic Ocean: a GEOTRACES case study

• Published in: Biogeosciences
• Main Authors: Menzel Barraqueta, Jan-Lukas, Klar, Jessica, Gledhill, Martha, Schlosser, Christian, Shelley, Rachel, Planquette, Hélène, Wenzel, Bernhard, Sarthou, Géraldine, Achterberg, Eric
• Other Authors: Helmholtz Centre for Ocean Research Kiel (GEOMAR), Stellenbosch University, National Oceanography Centre Southampton (NOC), University of Southampton, Laboratoire d'études en Géophysique et océanographie spatiales (LEGOS), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire Midi-Pyrénées (OMP), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National d'Études Spatiales Toulouse (CNES)-Centre National de la Recherche Scientifique (CNRS)-Météo-France-Centre National de la Recherche Scientifique (CNRS), 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), Department of Earth, Ocean and Atmospheric Science Tallahassee (FSU, Florida State University Tallahassee (FSU), School of Geography, Earth and Environmental Sciences Plymouth (SoGEES), Plymouth University
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: FLOW-INJECTION ANALYSIS; DISSOLVED ALUMINUM; TRACE-ELEMENTS; SURFACE WATERS; DUST DEPOSITION; SAHARAN DUST; EASTERN ATLANTIC; IRON DEPOSITION; SARGASSO SEA; AL; ACL; [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDE.BE]Environmental Sciences/Biodiversity and Ecology; North Atlantic
• Online Access: https://hal.science/hal-02322572; https://hal.science/hal-02322572/document; https://hal.science/hal-02322572/file/Menzel-Barraqueta_etal_Biogeosciences_2019.pdf; https://doi.org/10.5194/bg-16-1525-2019

International audience Atmospheric deposition is an important source of micronutrients to the ocean, but atmospheric deposition fluxes remain poorly constrained in most ocean regions due to the limited number of field observations of wet and dry atmospheric inputs. Here we present the distribution of dissolved aluminium (dAl), as a tracer of atmospheric inputs, in surface waters of the Atlantic Ocean along GEOTRACES sections GA01, GA06, GA08, and GA10. We used the surface mixed-layer concentrations of dAl to calculate atmospheric deposition fluxes using a simple steady state model. We have optimized the Al fractional aerosol solubility, the dAl residence time within the surface mixed layer and the depth of the surface mixed layer for each separate cruise to calculate the atmospheric deposition fluxes. We calculated the lowest deposition fluxes of 0.15 +/- 0.1 and 0.27 +/- 0.13 gm(-2) yr(-1) for the South and North Atlantic Ocean (>40 degrees S and > 40 degrees N) respectively, and the highest fluxes of 1.8 and 3.09 gm(-2) yr(-1) for the south-east Atlantic and tropical Atlantic Ocean, respectively. Overall, our estimations are comparable to atmospheric dust deposition model estimates and reported field-based atmospheric deposition estimates. We note that our estimates diverge from atmospheric dust de-position model flux estimates in regions influenced by riverine Al inputs and in upwelling regions. As dAl is a key trace element in the GEOTRACES programme, the approach presented in this study allows calculations of atmospheric deposition fluxes at high spatial resolution for remote ocean regions.