Dry and wet deposition of nutrients from the tropical Atlantic atmosphere: Links to primary productivity and nitrogen fixation.

Baker, A. R., Weston, K., Kelly, S. D., Voss, M., Streu, Peter and Cape, J .N. (2007) Dry and wet deposition of nutrients from the tropical Atlantic atmosphere: Links to primary productivity and nitrogen fixation. Deep Sea Research Part I: Oceanographic Research Papers, 54 (10). pp. 1704-1720. DOI 10.1016/j.dsr.2007.07.001.

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Abstract

Atmospheric deposition fluxes of soluble nutrients (N, P, Si, Fe, Co, Zn) to the tropical North Atlantic were determined during cruise M55 of the German SOLAS programme. Nutrient fluxes were highest in the east of the section along 10°N, owing to the proximity of source regions in West Africa and Europe, and lowest in the west, for both dry and wet deposition modes. In common with other recent studies, atmospheric P and Si inputs during M55 were strongly depleted relative to the stoichiometry of phytoplankton Fe, N, P and Si requirements. Atmospheric N inputs were equivalent to 0.1–4.7% of observed primary productivity during the cruise. Atmospheric nutrient supply was also compared to observed nitrogen fixation rates during M55. While atmospheric Fe supply may have been sufficient to support N fixation (depending on the relationship between our simple Fe leaching experiment and aerosol Fe dissolution in seawater), atmospheric P supply was well below the required rate. The stable nitrogen isotope composition of nitrate–N in aerosol and rain was also determined. Results of a simple model indicate that atmospheric deposition and nitrogen fixation introduce similar amounts of isotopically light nitrogen into surface waters of the study region. This implies that nitrogen isotope-based methods would overestimate nitrogen fixation here by a factor of 2, if atmospheric inputs were not taken into account.

Document Type: Article
Keywords: SOLAS; North Atlantic; Nutrients; Atmospheric deposition; Productivity; Nitrogen fixation; M55
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1016/j.dsr.2007.07.001
ISSN: 0967-0637
Expeditions/Models/Experiments:
Date Deposited: 03 Dec 2008 16:50
Last Modified: 01 Nov 2016 11:48
URI: http://oceanrep.geomar.de/id/eprint/5998

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