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BrCl production in NaBr/NaCl/HNO 3 /O 3 solutions representative of sea‐salt aerosols in the marine boundary layer
Author(s) -
Disselkamp R. S.,
Chapman E. G.,
Barchet W. R.,
Colson S. D.,
Howd C. D.
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl900251
Subject(s) - bromine , ozone , chlorine , sea salt , bromide , chemistry , salt (chemistry) , inorganic chemistry , halide , aerosol , ion , kinetics , nitric acid , ionic bonding , seawater , organic chemistry , geology , oceanography , physics , quantum mechanics
Atomic bromine and chlorine liberated from sea‐salt aerosol is thought to play an important role in chemistry of the marine boundary layer. Despite numerous modeling studies, no prior experimental investigations of the oxidation of halide species contained in simulated, or actual, sea‐salt solutions have been performed. We present laboratory data that examines chemistry in NaBr/NaCl/HNO 3 /O 3 solutions at 290 K. Ozonation experiments were performed by flowing ozone in air through a nitric acid/salt solution and monitoring pH with time using an ion‐sensitive electrode. The rate of oxidation was observed to be first order in ozone concentration and to have a non‐first order bromide concentration dependence. Ion Chromatography was used to measure both bromide disappearance as well as oxidation products formed during the course of the reactions studied. Our measurements of the oxidation rate versus ion concentration indicate that the high ionic strength present in sea‐salt aerosol will possess unique kinetics different from dilute solution behavior. In addition, our results are consistent with the reaction sequence O 3 + H + + Br − → O 2 + HOBr and HOBr + Cl − + H + → BrCl + H 2 O. These observations support the HOBr mediated Cl − oxidation process proposed previously (Vogt et al., 1996).