Atmospheric inorganic chlorine and bromine species in Arctic boundary layer of the winter/spring

Abstract

Atmospheric aerosol particles and inorganic acidic gases were simultaneously collected in Ny‐Ålesund (78°55'N, 11°56'E), Svalbard, during the winter/early‐spring seasons. Inorganic chlorine species were predominantly distributed in the particulate phase, which consisted of sea‐salt particles. Gaseous inorganic chlorine species probably arise via Cl− liberation from sea‐salt particles by acidic species such as sulfate. On the other hand, inorganic bromine species were mostly found in the gaseous phase. Moreover, the concentration of gaseous inorganic bromine species gradually increased from winter to early spring. The major particulate constituent was Br−, whose concentration exceeded to sea‐salt Br− concentration, whereas bromate (BrO3−) was also found as a minor particulate bromine constituent. Thus, inorganic bromine species were suggested to be accumulated in the boundary layer during the winter/early‐spring. Halogen liberation from sea‐salt particles was often observed in analyses of individual aerosol particles and size fractionation of aerosol constituents. Chlorine liberation mostly occurred in the fine particle mode (0.2 – 2.0 μm), while Br− liberation occurred in both coarse particle (>2.0 μm) and fine modes. Non‐sea‐salt Br− was predominantly distributed in fine and backup modes and internally mixed with fine sulfate particles.