The role of BrNO 3 in marine tropospheric chemistry: A model study

Laboratory studies have shown that bromine nitrate (BrNO 3 ) reacts on sulfuric acid and on ice particles. Here we investigate the potential role of BrNO 3 in the marine boundary layer (mbl) assuming that it reacts on sea‐salt particles as well. Using the chemical box model MOCCA we find that heterogeneous reactions of BrNO 3 on aerosol particles could affect the chemistry in four major ways: 1) They increase loss of NO x (=NO+NO 2 ) from the gas phase; 2) They accelerate loss of bromide and chloride from sea‐salt aerosols. This dehalogenation occurs without the consumption of aerosol acidity; 3) The resulting loss of NO x and the increase of gas‐phase bromine species both lead to O 3 destruction; 4) The resulting increase of reactive chlorine species affects gas‐phase hydrocarbons as well as S(IV) oxidation by HOCl in sea‐salt aerosols.