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Title: Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US

Abstract

During the summer 2013 Southern Aerosol and Oxidant Study (SOAS) field campaign in a rural site in the southeastern United States, the effect of hygroscopicity and composition on the phase state of atmospheric aerosol particles dominated by the organic fraction was studied. The analysis is based on hygroscopicity measurements by a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA), physical phase state investigations by an Aerosol Bounce Instrument (ABI) and composition measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). To study the effect of atmospheric aging on these properties, an OH-radical oxidation flow reactor (OFR) was used to simulate longer atmospheric aging times of up to 3 weeks. Hygroscopicity and bounce behavior of the particles had a clear relationship showing higher bounce at elevated relative humidity (RH) values for less hygroscopic particles, which agrees well with earlier laboratory studies. Additional OH oxidation of the aerosol particles in the OFR increased the O:C and the hygroscopicity resulting in liquefying of the particles at lower RH values. At the highest OH exposures, the inorganic fraction starts to dominate the bounce process due to production of inorganics and concurrent loss of organics in the OFR. Our results indicate that at typical ambient RH andmore » temperature, organic-dominated particles stay mostly liquid in the atmospheric conditions in the southeastern US, but they often turn semisolid when dried below ~50 % RH in the sampling inlets. Furthermore, while the liquid phase state suggests solution behavior and equilibrium partitioning for the SOA particles in ambient air, the possible phase change in the drying process highlights the importance of thoroughly considered sampling techniques of SOA particles.« less

Authors:
 [1];  [2];  [3];  [4];  [1];  [2];  [1];  [4];  [2];  [1]
  1. Univ. of Eastern Finland, Kuopio (Finland)
  2. Univ. of Colorado, Boulder, CO (United States)
  3. Univ. of Eastern Finland, Kuopio (Finland); Rice Univ., Houston, TX (United States)
  4. Texas A & M Univ., College Station, TX (United States)
Publication Date:
Research Org.:
Univ. of Colorado, Boulder, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23)
OSTI Identifier:
1360105
Grant/Contract Number:
SC0011105
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 16; Journal Issue: 17; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Country of Publication:
United States
Language:
English
Subject:
29 ENERGY PLANNING, POLICY, AND ECONOMY

Citation Formats

Pajunoja, Aki, Hu, Weiwei, Leong, Yu J., Taylor, Nathan F., Miettinen, Pasi, Palm, Brett B., Mikkonen, Santtu, Collins, Don R., Jimenez, Jose L., and Virtanen, Annele. Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US. United States: N. p., 2016. Web. doi:10.5194/acp-16-11163-2016.
Pajunoja, Aki, Hu, Weiwei, Leong, Yu J., Taylor, Nathan F., Miettinen, Pasi, Palm, Brett B., Mikkonen, Santtu, Collins, Don R., Jimenez, Jose L., & Virtanen, Annele. Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US. United States. doi:10.5194/acp-16-11163-2016.
Pajunoja, Aki, Hu, Weiwei, Leong, Yu J., Taylor, Nathan F., Miettinen, Pasi, Palm, Brett B., Mikkonen, Santtu, Collins, Don R., Jimenez, Jose L., and Virtanen, Annele. 2016. "Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US". United States. doi:10.5194/acp-16-11163-2016. https://www.osti.gov/servlets/purl/1360105.
@article{osti_1360105,
title = {Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US},
author = {Pajunoja, Aki and Hu, Weiwei and Leong, Yu J. and Taylor, Nathan F. and Miettinen, Pasi and Palm, Brett B. and Mikkonen, Santtu and Collins, Don R. and Jimenez, Jose L. and Virtanen, Annele},
abstractNote = {During the summer 2013 Southern Aerosol and Oxidant Study (SOAS) field campaign in a rural site in the southeastern United States, the effect of hygroscopicity and composition on the phase state of atmospheric aerosol particles dominated by the organic fraction was studied. The analysis is based on hygroscopicity measurements by a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA), physical phase state investigations by an Aerosol Bounce Instrument (ABI) and composition measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). To study the effect of atmospheric aging on these properties, an OH-radical oxidation flow reactor (OFR) was used to simulate longer atmospheric aging times of up to 3 weeks. Hygroscopicity and bounce behavior of the particles had a clear relationship showing higher bounce at elevated relative humidity (RH) values for less hygroscopic particles, which agrees well with earlier laboratory studies. Additional OH oxidation of the aerosol particles in the OFR increased the O:C and the hygroscopicity resulting in liquefying of the particles at lower RH values. At the highest OH exposures, the inorganic fraction starts to dominate the bounce process due to production of inorganics and concurrent loss of organics in the OFR. Our results indicate that at typical ambient RH and temperature, organic-dominated particles stay mostly liquid in the atmospheric conditions in the southeastern US, but they often turn semisolid when dried below ~50 % RH in the sampling inlets. Furthermore, while the liquid phase state suggests solution behavior and equilibrium partitioning for the SOA particles in ambient air, the possible phase change in the drying process highlights the importance of thoroughly considered sampling techniques of SOA particles.},
doi = {10.5194/acp-16-11163-2016},
journal = {Atmospheric Chemistry and Physics (Online)},
number = 17,
volume = 16,
place = {United States},
year = 2016,
month = 9
}

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