ABSTRACT The importance of methyl bromide as a source for stratospheric bromine has led to its planned phase-out as an agricultural fumigant as part of the Montreal Protocol and Clean Air Act. However, there is significant uncertainty regarding the global budget of tropospheric methyl bromide and the role of the ocean as a source or sink. The oceanic lifetime of methyl bromide is an important parameter in global models seeking to predict the atmospheric response to proposed changes in emissions of methyl bromide. In this project, investigators at the University of Miami and the University of Connecticut will conduct laboratory experiments as well as studies at sea to determine whether biological removal of methyl bromide from surface seawater proceeds ar rates sufficient to affect the oceanic lifetime of this compound. The current state of knowledge allows prediction of its turnover rate through purely chemical (non-biological) pathways; little is known of microbiological impacts. If biological removal is significant, it will alter our current concept and quantitative modeling of the global cycling of methyl bromide.
