ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-1805-2009 Air-sea fluxes of biogenic bromine from the tropical and North Atlantic Ocean Carpenter L. J. 1 Jones C. E. 1 Dunk R. M. 1 3 Hornsby K. E. 1 Woeltjen J. 2 Department of Chemistry, University of York, York, YO10 5DD, UK Laboratory for Global Marine and Atmospheric Chemistry, School of Environmental Sciences, University of East Anglia, Norwich, NR4 7TJ, UK now at: Crichton Carbon Centre, Crichton University Campus, Dumfries, DG1 4ZL, UK 11 03 2009 9 5 1805 1816 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/9/1805/2009/acp-9-1805-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/1805/2009/acp-9-1805-2009.pdf

Air-sea fluxes and bulk seawater and atmospheric concentrations of bromoform (CHBr<sub>3</sub>) and dibromomethane (CH<sub>2</sub>Br<sub>2</sub>) were measured during two research cruises in the northeast Atlantic (53–59&deg; N, June–July 2006) and tropical eastern Atlantic Ocean including over the African coastal upwelling system (16–35&deg; N May–June 2007). Saturations and sea-air fluxes of these compounds generally decreased in the order coastal &gt; upwelling &gt; shelf &gt; open ocean, and outside of coastal regions, a broad trend of elevated surface seawater concentrations with high chlorophyll-<i>a</i> was observed. We show that upwelling regions (coastal and equatorial) represent regional hot spots of bromocarbons, but are probably not of major significance globally, contributing at most a few percent of the total global emissions of CHBr<sub>3</sub> and CH<sub>2</sub>Br<sub>2</sub>. From limited data from eastern Atlantic coastlines, we tentatively suggest that globally, coastal oceans (depth &lt;180 m) together contribute ~2.5 (1.4–3.5) Gmol Br yr<sup>&minus;1</sup> of CHBr<sub>3</sub>, excluding influences from anthropogenic sources such as coastal power stations. This flux estimate is close to current estimates of the total open ocean source. We also show that the concentration ratio of CH<sub>2</sub>Br<sub>2</sub>/CHBr<sub>3</sub> in seawater is a strong function of concentration (and location), with a lower CH<sub>2</sub>Br<sub>2</sub>/CHBr<sub>3</sub> ratio found in coastal regions near to macroalgal sources.

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