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Radical‐initiated formation of organosulfates and surfactants in atmospheric aerosols
Author(s) -
Nozière Barbara,
Ekström Sanna,
Alsberg Tomas,
Holmström Sara
Publication year - 2010
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 - 10.1029/2009gl041683
Subject(s) - methacrolein , isoprene , methyl vinyl ketone , sulfate , ammonium sulfate , chemistry , aerosol , cloud condensation nuclei , environmental chemistry , organic chemistry , monomer , copolymer , catalysis , methacrylic acid , polymer
Many atmospheric aerosols contain both organic compounds and inorganic material, such as sulfate salts. In this work, we show that these sulfates could trigger some chemical transformations of the organic compounds by producing sulfate radicals, SO 4 − , when exposed to UV light (280–320 nm). In particular, we show by mass spectrometry (LC/ESI‐MSMS) that isoprene, methyl vinyl ketone, methacrolein, and α ‐pinene in irradiated sulfate solutions (ammonium and sodium sulfate) produce the same organosulfates as previously identified in aerosols, and even some that had remained unidentified until now. With a typical time constant of 9 h instead of 4600 days for esterifications, these radical reactions would be a plausible origin for the atmospheric organosulfates. These reactions also produced efficient surfactants, possibly resembling the long‐chain organosulfates found in the experiments. Thus, photochemistry in mixed sulfate/organic aerosols could increase cloud condensation nuclei (CCN) numbers, which would be supported by previous atmospheric observations.