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An Experimental Assessment of the Importance of S(IV) Oxidation by Hypohalous Acids in the Marine Atmosphere
Author(s) -
Liu Tengyu,
Abbatt Jonathan P.D.
Publication year - 2020
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 - 10.1029/2019gl086465
Subject(s) - atmosphere (unit) , sulfate , aerosol , chemistry , kinetics , environmental chemistry , atmospheric chemistry , sulfate aerosol , scavenging , salt (chemistry) , ozone , meteorology , organic chemistry , physics , quantum mechanics , antioxidant
Hypohalous acids (HOCl + HOBr) play an important but highly uncertain role in sulfate aerosol production in the marine atmosphere due to the unmeasured reaction rate constants ( k ) of HOCl/HOBr and HSO 3 − , the dominant S(IV) species in acidified sea salt aerosols and cloudwater. We directly determined k HOCl + HSO 3 −by investigating the kinetics of aqueous oxidation of dissolved SO 2 by HOCl in low pH aerosol particles in a flow tube. Further, we predicted k HOBr + HSO 3 −using a novel kinetics model developed from the HOCl/HSO 3 − results. k HOBr + HSO 3 −and k HOCl + HSO 3 −were estimated to be 2 and 3 orders of magnitude lower, respectively, than the values used in atmospheric models. We assess the importance of halogen‐driven S(IV) oxidation in the marine atmosphere with this new fundamental understanding and find that in‐cloud sulfate production via HOBr oxidation remains an important atmospheric process, but the HOCl oxidation pathway in acidified sea salt aerosols is unlikely to be important.