Air-sea fluxes of biogenic bromine from the tropical and North Atlantic Ocean

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 decreased in the order coastal > upwelling > shelf > open ocean, and outside of coastal regions, a broad trend of elevated surface seawater concentrations with high chlorophyll-a 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 CHBr3 and CH2Br2. From limited data from eastern Atlantic coastlines, we tentatively suggest that globally, coastal oceans (dept