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Atmos. Chem. Phys. Discuss., 8, 18409-18435, 2008
www.atmos-chem-phys-discuss.net/8/18409/2008/ doi:10.5194/acpd-8-18409-2008 © Author(s) 2008. This work is distributed under the Creative Commons Attribution 3.0 License. |
Air-sea fluxes of biogenic bromine from the tropical and North Atlantic Ocean
1Department of Chemistry, University of York, York, YO10 5DD, UK
*now at: Crichton Carbon Centre, Crichton University Campus, Dumfries, DG1 4ZL, UK
Abstract. Air-sea fluxes and bulk seawater and atmospheric concentrations of bromoform (CHBr3) and dibromomethane (CH2Br2) were measured during two research cruises in the northeast Atlantic (53–59° N, June–July 2006) and tropical eastern Atlantic Ocean including over the African coastal upwelling system (16–35° N May–June 2007). Saturations and sea-air fluxes of these compounds generally decrease in the order coastal>upwelling>shelf>open ocean, and a broad trend of elevated surface seawater concentrations with high chlorophylla was observed. From limited data from eastern Atlantic coastlines, we tentatively suggest that globally, coastal and coastally-influenced waters together contribute ~2.4 Gmol Br yr−1 (24–56%) of CHBr3. We show that upwelling regions (coastal and equatorial) represent regional hot spots of bromocarbons, but are probably not of major significance globally, contributing only a few percent of the total global emissions of CHBr3 and CH2Br2. We also show that the concentration ratio of CH2Br2/CHBr3 in seawater is a strong function of concentration (and location), with a lower CH2Br2/CHBr3 ratio found in coastal regions near to macroalgal sources.
Citation: Carpenter, L. J., Jones, C. E., Dunk, R. M., and Hornsby, K. E.: Air-sea fluxes of biogenic bromine from the tropical and North Atlantic Ocean, Atmos. Chem. Phys. Discuss., 8, 18409-18435, doi:10.5194/acpd-8-18409-2008, 2008.