Abstract:
:Recent laboratory studies have demonstrated that isoprene oxidation products can partition to atmospheric aerosols by reacting with condensed phase sulfuric acid, forming low-volatility organosulfate compounds. We have identified organosulfate compounds in free tropospheric aerosols by single particle mass spectrometry during several airborne field campaigns. One of these organosulfates is identified as the sulfate ester of IEPOX, a second generation oxidation product of isoprene. The patterns of IEPOX sulfate ester in ambient data generally followed the aerosol acidity and NO(x) dependence established by laboratory studies. Detection of the IEPOX sulfate ester was most sensitive using reduced ionization laser power, when it was observed in up to 80% of particles in the tropical free troposphere. Based on laboratory mass calibrations, IEPOX added > 0.4% to tropospheric aerosol mass in the remote tropics and up to 20% in regions downwind of isoprene sources. In the southeastern United States, when acidic aerosol was exposed to fresh isoprene emissions, accumulation of IEPOX increased aerosol mass by up to 3%. The IEPOX sulfate ester is therefore one of the most abundant single organic compounds measured in atmospheric aerosol. Our data show that acidity-dependent IEPOX uptake is a mechanism by which anthropogenic SO(2) and marine dimethyl sulfide emissions generate secondary biogenic aerosol mass throughout the troposphere.
journal_name
Proc Natl Acad Sci U S Aauthors
Froyd KD,Murphy SM,Murphy DM,de Gouw JA,Eddingsaas NC,Wennberg POdoi
10.1073/pnas.1012561107subject
Has Abstractpub_date
2010-12-14 00:00:00pages
21360-5issue
50eissn
0027-8424issn
1091-6490pii
1012561107journal_volume
107pub_type
杂志文章abstract::A recent study showed that limited trypsin treatment of liposomes containing purified Electrophorus electricus sodium channels activates a sodium radiotracer flux. We now report that similarly treated sodium channels show voltage-gated, tetrodotoxin-sensitive and highly sodium-selective single-channel currents when in...
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