Atmospheric deposition fluxes over the Atlantic Ocean: A GEOTRACES case study.

Menzel Barraqueta, Jan-Lukas , Klar, Jessica K., Gledhill, Martha , Schlosser, Christian , Shelley, Rachel, Planquette, Hélène, Wenzel, Bernhard, Sarthou, Geraldine and Achterberg, Eric P. (2019) Atmospheric deposition fluxes over the Atlantic Ocean: A GEOTRACES case study. Open Access Biogeosciences (BG), 16 . pp. 1525-1542. DOI 10.5194/bg-16-1525-2019.

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Abstract

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 aerosol Al fractional solubility, dAl residence time within the surface mixed layer and 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 g m−2 yr−1 for the South and North Atlantic Ocean (> 40° S and > 40° N), respectively, and highest fluxes of 2.67 ± 1.96 and 3.82 ± 2.72 g m−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 deposition 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.

Document Type: Article
Keywords: ocean, dust, aluminium, aluminum, dissolution, deposition synthesis
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
NOC
IFREMER
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-16-1525-2019
ISSN: 1726-4170
Projects: GEOTRACES
Date Deposited: 15 May 2018 07:13
Last Modified: 12 Apr 2019 07:27
URI: http://oceanrep.geomar.de/id/eprint/43047

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