Photochemical bromine production implicated in Arctic boundary-layer ozone depletion

摘要: RECENT measurements1–7 in the Arctic have revealed episodic destruction of boundary-layer ozone from 30–40 parts per 109 by volume (p.p.b.v.) to undetectable levels on a timescale less than day, during periods when boundary layer is very stable. The begins at polar sunrise, continues for months March and April, strongly associated with filterable bromine which are much greater rest year. Here we suggest that sea-salt Br− reaches high concentrations snow pack long night, evolved into atmosphere as Br2at sunrise. Ordinarily, gas-phase photochemistry would convert Br2 HBr or brominated organic compounds consequently little ozone. In view several laboratory experiments8–11, analogy marine layer12, propose will be scavenged ambient aerosols ice crystals, these heterogeneous reactions release back atmosphere. We argue this cycling between aerosol gas phase should maintain sufficiently Br atoms BrO radicals destroy ozone, agreement observations1–7.