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

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

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 th e surface mixed layer for each separate cruise to calculate the atmosphericdeposition fluxes. We calculated the lowest deposition fluxes of 0:150:1 and 0:27 0:13 gm2 yr1 for the South and North Atlantic Ocean (> 40 S and > 40 N) respectively, and the highest fluxes of 1.8 and 3.09 gm2 yr1 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.

1726-4170
1525-1542
Barraqueta, Jan Lukas Menzel
8ecdc960-5a45-4158-b2ba-f351c54e10d6
Klar, Jessica
817e4fe3-d923-4e9c-84da-a511f602b4f8
Gledhill, Martha
da795c1e-1489-4d40-9df1-fc6bde54382d
Schlosser, Christian
93df4206-5ae4-48a3-80b9-d6f4fc2d4b0a
Shelley, Rachel
237387ff-444d-428d-b5d2-79e3a4667e05
Planquette, Helene F.
6956a009-302b-4485-82d7-8879a99d9ed1
Wenzel, Bernhard
6251cca0-02b9-4999-b477-c9cca6ddfaef
Sarthou, Geraldine
aa083f34-dd2a-4b58-93e2-1f1080f0d29c
Achterberg, Eric
685ce961-8c45-4503-9f03-50f6561202b9
Barraqueta, Jan Lukas Menzel
8ecdc960-5a45-4158-b2ba-f351c54e10d6
Klar, Jessica
817e4fe3-d923-4e9c-84da-a511f602b4f8
Gledhill, Martha
da795c1e-1489-4d40-9df1-fc6bde54382d
Schlosser, Christian
93df4206-5ae4-48a3-80b9-d6f4fc2d4b0a
Shelley, Rachel
237387ff-444d-428d-b5d2-79e3a4667e05
Planquette, Helene F.
6956a009-302b-4485-82d7-8879a99d9ed1
Wenzel, Bernhard
6251cca0-02b9-4999-b477-c9cca6ddfaef
Sarthou, Geraldine
aa083f34-dd2a-4b58-93e2-1f1080f0d29c
Achterberg, Eric
685ce961-8c45-4503-9f03-50f6561202b9

Barraqueta, Jan Lukas Menzel, Klar, Jessica, Gledhill, Martha, Schlosser, Christian, Shelley, Rachel, Planquette, Helene F., Wenzel, Bernhard, Sarthou, Geraldine and Achterberg, Eric (2019) Atmospheric deposition fluxes over the Atlantic Ocean: A GEOTRACES case study. Biogeosciences, 16 (7), 1525-1542. (doi:10.5194/bg-16-1525-2019).

Record type: Article

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 Al fractional aerosol solubility, the dAl residence time within the surface mixed layer and the depth of th e surface mixed layer for each separate cruise to calculate the atmosphericdeposition fluxes. We calculated the lowest deposition fluxes of 0:150:1 and 0:27 0:13 gm2 yr1 for the South and North Atlantic Ocean (> 40 S and > 40 N) respectively, and the highest fluxes of 1.8 and 3.09 gm2 yr1 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.

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Accepted/In Press date: 14 January 2019
e-pub ahead of print date: 21 February 2019

Identifiers

Local EPrints ID: 430672
URI: http://eprints.soton.ac.uk/id/eprint/430672
ISSN: 1726-4170
PURE UUID: 5e9182f5-71d4-419c-aa4a-cd93c93302ef

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Date deposited: 08 May 2019 16:30
Last modified: 16 Dec 2019 17:38

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