Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface
<p>Water-soluble brown carbon in the aqueous core of aerosol may play a role in the photochemical aging of organic film on the aerosol surface. To better understand the reactivity and photochemical aging processes of organic coating on the aqueous aerosol surface, we have simulated the photose...
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2019-08-01
|
| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/19/9887/2019/acp-19-9887-2019.pdf |
| _version_ | 1818925046097248256 |
|---|---|
| author | S. Li X. Jiang M. Roveretto C. George C. George L. Liu W. Jiang Q. Zhang W. Wang M. Ge L. Du |
| author_facet | S. Li X. Jiang M. Roveretto C. George C. George L. Liu W. Jiang Q. Zhang W. Wang M. Ge L. Du |
| author_sort | S. Li |
| collection | DOAJ |
| description | <p>Water-soluble brown carbon in the aqueous core of aerosol
may play a role in the photochemical aging of organic film on the aerosol
surface. To better understand the reactivity and photochemical aging
processes of organic coating on the aqueous aerosol surface, we have
simulated the photosensitized reaction of organic films made of several long-chain fatty acids in a Langmuir trough in the presence or absence of
irradiation. Several chemicals (imidazole-2-carboxaldehyde and humic acid),
PM<span class="inline-formula"><sub>2.5</sub></span> samples collected from the field, and secondary organic aerosol
samples generated from a simulation chamber were used as photosensitizers to
be involved in the photochemistry of the organic films. Stearic acid,
elaidic acid, oleic acid, and two different phospholipids with the same
carbon chain length and different degrees of saturation, i.e.
1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and
1,2-dioleoylsn-glycero-3-phosphocholine (DOPC), were chosen as the common
organic film-forming species in this analysis. The double bond (<i>trans</i> and <i>cis</i>) in
unsaturated organic compounds has an effect on the surface area of the
organic monolayer. The oleic acid (OA) monolayer possessing a <i>cis</i> double bond
in an alkyl chain is more expanded than elaidic acid (EA) monolayers on
artificial seawater that contain a photosensitizer. Monitoring the change in
the relative area of DOPC monolayers has shown that DOPC does not react with
photosensitizers under dark conditions. Instead, the photochemical reaction
initiated by the excited photosensitizer and molecular oxygen can generate
new unsaturated products in the DOPC monolayers, accompanied by an increase
in the molecular area. The DSPC monolayers did not yield any photochemical
oxidized products under the same conditions. The spectra measured with
polarization modulation-infrared reflection–absorption spectroscopy
(PM-IRRAS) were also consistent with the results of a surface pressure–area
isotherm. Here, a reaction mechanism explaining these observations is
presented and discussed. The results of PM<span class="inline-formula"><sub>2.5</sub></span> and SOA samples will
contribute to our understanding of the processing of organic aerosol aging
that alters the aerosol composition.</p> |
| first_indexed | 2024-12-20T02:34:59Z |
| format | Article |
| id | doaj.art-5396a9ba073341b487a9bccaae26f648 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-20T02:34:59Z |
| publishDate | 2019-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-5396a9ba073341b487a9bccaae26f6482022-12-21T19:56:27ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242019-08-01199887990210.5194/acp-19-9887-2019Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interfaceS. Li0X. Jiang1M. Roveretto2C. George3C. George4L. Liu5W. Jiang6Q. Zhang7W. Wang8M. Ge9L. Du10Environment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaUniversity of Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, 69626 Villeurbanne, FranceSchool of Environmental Science and Engineering, Shandong University, Binhai Road 72, Qingdao 266237, ChinaUniversity of Lyon, Université Claude Bernard Lyon 1, CNRS, IRCELYON, 69626 Villeurbanne, FranceEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, ChinaState Key Laboratory for Structural Chemistry of Unstable and Stable Species, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, ChinaEnvironment Research Institute, Shandong University, Binhai Road 72, Qingdao 266237, China<p>Water-soluble brown carbon in the aqueous core of aerosol may play a role in the photochemical aging of organic film on the aerosol surface. To better understand the reactivity and photochemical aging processes of organic coating on the aqueous aerosol surface, we have simulated the photosensitized reaction of organic films made of several long-chain fatty acids in a Langmuir trough in the presence or absence of irradiation. Several chemicals (imidazole-2-carboxaldehyde and humic acid), PM<span class="inline-formula"><sub>2.5</sub></span> samples collected from the field, and secondary organic aerosol samples generated from a simulation chamber were used as photosensitizers to be involved in the photochemistry of the organic films. Stearic acid, elaidic acid, oleic acid, and two different phospholipids with the same carbon chain length and different degrees of saturation, i.e. 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and 1,2-dioleoylsn-glycero-3-phosphocholine (DOPC), were chosen as the common organic film-forming species in this analysis. The double bond (<i>trans</i> and <i>cis</i>) in unsaturated organic compounds has an effect on the surface area of the organic monolayer. The oleic acid (OA) monolayer possessing a <i>cis</i> double bond in an alkyl chain is more expanded than elaidic acid (EA) monolayers on artificial seawater that contain a photosensitizer. Monitoring the change in the relative area of DOPC monolayers has shown that DOPC does not react with photosensitizers under dark conditions. Instead, the photochemical reaction initiated by the excited photosensitizer and molecular oxygen can generate new unsaturated products in the DOPC monolayers, accompanied by an increase in the molecular area. The DSPC monolayers did not yield any photochemical oxidized products under the same conditions. The spectra measured with polarization modulation-infrared reflection–absorption spectroscopy (PM-IRRAS) were also consistent with the results of a surface pressure–area isotherm. Here, a reaction mechanism explaining these observations is presented and discussed. The results of PM<span class="inline-formula"><sub>2.5</sub></span> and SOA samples will contribute to our understanding of the processing of organic aerosol aging that alters the aerosol composition.</p>https://www.atmos-chem-phys.net/19/9887/2019/acp-19-9887-2019.pdf |
| spellingShingle | S. Li X. Jiang M. Roveretto C. George C. George L. Liu W. Jiang Q. Zhang W. Wang M. Ge L. Du Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface Atmospheric Chemistry and Physics |
| title | Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface |
| title_full | Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface |
| title_fullStr | Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface |
| title_full_unstemmed | Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface |
| title_short | Photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air–aqueous interface |
| title_sort | photochemical aging of atmospherically reactive organic compounds involving brown carbon at the air aqueous interface |
| url | https://www.atmos-chem-phys.net/19/9887/2019/acp-19-9887-2019.pdf |
| work_keys_str_mv | AT sli photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT xjiang photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT mroveretto photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT cgeorge photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT cgeorge photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT lliu photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT wjiang photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT qzhang photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT wwang photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT mge photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface AT ldu photochemicalagingofatmosphericallyreactiveorganiccompoundsinvolvingbrowncarbonattheairaqueousinterface |