Photochemical oxidation and changes in molecular composition of organic aerosol in the regional context. Robinson, A., L.; Donahue, N., M.; and Rogge, W., F. J. Geophys. Res.-Atmos., 2006.
abstract   bibtex   
[1] This paper presents evidence that condensed-phase organic compounds are significantly oxidized in regional air masses and in locations affected by regional transport, especially during the summer. The core of the paper examines a large data set of ambient organic aerosol concentrations for removal of reactive compounds relative to less-reactive compounds. The approach allows visualization of both photochemistry and mixing of emissions from multiple sources in order to differentiate between the two phenomena. The focus is on hopanes and alkenoic acids, important markers for motor vehicle and cooking emissions. Ambient data from Pittsburgh, PA and the Southeastern United States contain evidence for significant photochemical oxidation of these compounds in the summertime. There is a strong seasonal pattern in the ratio of different hopanes to elemental carbon consistent with oxidation. In addition, measurements at rural sites indicate that hopanes are severely depleted in the regional air mass during the summer. Alkenoic acids also appear to be photochemically oxidized during the summertime; however, the oxidation rate appears to be much slower than that inferred from laboratory experiments. The significance of photochemistry is supported by rudimentary calculations which indicate substantial oxidation by OH radicals and ozone on a time scale of a few days or so, comparable to time scales for regional transport. Oxidation is non-linear; therefore it represents a very substantial complication to linear source apportionment techniques such as the Chemical Mass Balance model. C1 Carnegie Mellon Univ, Dept Mech Engn, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Dept Engn & Publ Policy, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA 15213 USA. Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213 USA. Florida Int Univ, Dept Civil & Environm Engn, Miami, FL 33199 USA.
@article{
 title = {Photochemical oxidation and changes in molecular composition of organic aerosol in the regional context},
 type = {article},
 year = {2006},
 volume = {111},
 id = {4fb0e188-8ae4-3a64-bcc3-619611eb27d4},
 created = {2014-10-08T16:28:18.000Z},
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 profile_id = {363623ef-1990-38f1-b354-f5cdaa6548b2},
 group_id = {02267cec-5558-3876-9cfc-78d056bad5b9},
 last_modified = {2017-03-14T17:32:24.802Z},
 read = {false},
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 authored = {false},
 confirmed = {true},
 hidden = {false},
 citation_key = {Robinson:JGRA:2006a},
 source_type = {article},
 private_publication = {false},
 abstract = {[1] This paper presents evidence that condensed-phase
organic compounds are significantly oxidized in regional air masses
and in locations affected by regional transport, especially during
the summer. The core of the paper examines a large data set of
ambient organic aerosol concentrations for removal of reactive
compounds relative to less-reactive compounds. The approach allows
visualization of both photochemistry and mixing of emissions from
multiple sources in order to differentiate between the two
phenomena. The focus is on hopanes and alkenoic acids, important
markers for motor vehicle and cooking emissions. Ambient data from
Pittsburgh, PA and the Southeastern United States contain evidence
for significant photochemical oxidation of these compounds in the
summertime. There is a strong seasonal pattern in the ratio of
different hopanes to elemental carbon consistent with oxidation. In
addition, measurements at rural sites indicate that hopanes are
severely depleted in the regional air mass during the summer.
Alkenoic acids also appear to be photochemically oxidized during
the summertime; however, the oxidation rate appears to be much
slower than that inferred from laboratory experiments. The
significance of photochemistry is supported by rudimentary
calculations which indicate substantial oxidation by OH radicals
and ozone on a time scale of a few days or so, comparable to time
scales for regional transport. Oxidation is non-linear; therefore
it represents a very substantial complication to linear source
apportionment techniques such as the Chemical Mass Balance model.
C1 Carnegie Mellon Univ, Dept Mech Engn, Pittsburgh, PA 15213 USA.
Carnegie Mellon Univ, Dept Engn & Publ Policy, Pittsburgh, PA
15213 USA. Carnegie Mellon Univ, Dept Chem Engn, Pittsburgh, PA
15213 USA. Carnegie Mellon Univ, Dept Chem, Pittsburgh, PA 15213
USA. Florida Int Univ, Dept Civil & Environm Engn, Miami, FL 33199
USA.},
 bibtype = {article},
 author = {Robinson, A L and Donahue, N M and Rogge, W F},
 journal = {J. Geophys. Res.-Atmos.}
}
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