Natural and anthropogenic sources of bromoform and dibromomethane in the oceanographic and biogeochemical regime of the subtropical North East Atlantic.

The organic bromine compounds bromoform (CHBr) and dibromomethane (CHBr) influence tropospheric chemistry and stratospheric ozone depletion. Their atmospheric abundance is generally related to a common marine source, which is not well characterized. A cruise between the three Macaroenesian Archipelagos of Cape Verde, the Canaries and Madeira revealed that anthropogenic sources increased oceanic CHBr emissions significantly close to some islands, especially at the Canaries, while heterotrophic processes in the ocean increased the flux of CHBr from the sea to the atmosphere in the Cape Verde region.