The partitioning of bromine in the lower troposphere between particulate, inorganic gaseous, and organic gaseous phases was measured during the arctic spring. Rapid photochemical production of particulate Br- from organic gaseous Br was indicated by 1) an inverse correlation between particulate bromide and organic gaseous bromine (r2=-0.67), 2) a diurnal cycle in the ratio of these two phases, and 3) a diurnal cycle in the ratio of organic gaseous Br to Cl. Organic gaseous Br and Cl were correlated (r2=0.67) indicating a common, possibly marine, source. ¿ American Geophysical Union 1993