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Effect of solubility limitation on hygroscopic growth and cloud drop activation of SOA particles produced from traffic exhausts

Wittbom, C. LU ; Eriksson, A. C. LU ; Rissler, J. LU ; Roldin, P. LU ; Nordin, E. Z. LU ; Sjogren, S. LU ; Nilsson, P. T. LU ; Swietlicki, E. LU ; Pagels, J. LU and Svenningsson, B. LU (2018) In Journal of Atmospheric Chemistry 75(4). p.359-383
Abstract

Hygroscopicity measurements of secondary organic aerosol (SOA) particles often show inconsistent results between the supersaturated and subsaturated regimes, with higher activity as cloud condensation nucleus (CCN) than indicated by hygroscopic growth. In this study, we have investigated the discrepancy between the two regimes in the Lund University (LU) smog chamber. Various anthropogenic SOA were produced from mixtures of different precursors: anthropogenic light aromatic precursors (toluene and m-xylene), exhaust from a diesel passenger vehicle spiked with the light aromatic precursors, and exhaust from two different gasoline-powered passenger vehicles. Three types of seed particles were used: soot aggregates from a diesel vehicle,... (More)

Hygroscopicity measurements of secondary organic aerosol (SOA) particles often show inconsistent results between the supersaturated and subsaturated regimes, with higher activity as cloud condensation nucleus (CCN) than indicated by hygroscopic growth. In this study, we have investigated the discrepancy between the two regimes in the Lund University (LU) smog chamber. Various anthropogenic SOA were produced from mixtures of different precursors: anthropogenic light aromatic precursors (toluene and m-xylene), exhaust from a diesel passenger vehicle spiked with the light aromatic precursors, and exhaust from two different gasoline-powered passenger vehicles. Three types of seed particles were used: soot aggregates from a diesel vehicle, soot aggregates from a flame soot generator and ammonium sulphate (AS) particles. The hygroscopicity of seed particles with condensed, photochemically produced, anthropogenic SOA was investigated with respect to critical supersaturation (sc) and hygroscopic growth factor (gf) at 90% relative humidity. The hygroscopicity parameter κ was calculated for the two regimes: κsc and κgf, from measurements of sc and gf, respectively. The two κ showed significant discrepancies, with a κgfsc ratio closest to one for the gasoline experiments with ammonium sulphate seed and lower for the soot seed experiments. Empirical observations of sc and gf were compared to theoretical predictions, using modified Köhler theory where water solubility limitations were taken into account. The results indicate that the inconsistency between measurements in the subsaturated and supersaturated regimes may be explained by part of the organic material in the particles produced from anthropogenic precursors having a limited solubility in water.

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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Critical supersaturation, Hygroscopic growth, Particles, SOA, Solubility, Traffic exhausts
in
Journal of Atmospheric Chemistry
volume
75
issue
4
pages
359 - 383
publisher
Springer
external identifiers
  • scopus:85057081647
ISSN
0167-7764
DOI
10.1007/s10874-018-9380-5
language
English
LU publication?
yes
id
d8038efc-c0aa-4378-a981-68b1ab190f3d
date added to LUP
2018-12-04 12:52:34
date last changed
2019-02-20 11:38:57
@article{d8038efc-c0aa-4378-a981-68b1ab190f3d,
  abstract     = {<p>Hygroscopicity measurements of secondary organic aerosol (SOA) particles often show inconsistent results between the supersaturated and subsaturated regimes, with higher activity as cloud condensation nucleus (CCN) than indicated by hygroscopic growth. In this study, we have investigated the discrepancy between the two regimes in the Lund University (LU) smog chamber. Various anthropogenic SOA were produced from mixtures of different precursors: anthropogenic light aromatic precursors (toluene and m-xylene), exhaust from a diesel passenger vehicle spiked with the light aromatic precursors, and exhaust from two different gasoline-powered passenger vehicles. Three types of seed particles were used: soot aggregates from a diesel vehicle, soot aggregates from a flame soot generator and ammonium sulphate (AS) particles. The hygroscopicity of seed particles with condensed, photochemically produced, anthropogenic SOA was investigated with respect to critical supersaturation (s<sub>c</sub>) and hygroscopic growth factor (gf) at 90% relative humidity. The hygroscopicity parameter κ was calculated for the two regimes: κ<sub>sc</sub> and κ<sub>gf</sub>, from measurements of s<sub>c</sub> and gf, respectively. The two κ showed significant discrepancies, with a κ<sub>gf</sub> /κ<sub>sc</sub> ratio closest to one for the gasoline experiments with ammonium sulphate seed and lower for the soot seed experiments. Empirical observations of s<sub>c</sub> and gf were compared to theoretical predictions, using modified Köhler theory where water solubility limitations were taken into account. The results indicate that the inconsistency between measurements in the subsaturated and supersaturated regimes may be explained by part of the organic material in the particles produced from anthropogenic precursors having a limited solubility in water.</p>},
  author       = {Wittbom, C. and Eriksson, A. C. and Rissler, J. and Roldin, P. and Nordin, E. Z. and Sjogren, S. and Nilsson, P. T. and Swietlicki, E. and Pagels, J. and Svenningsson, B.},
  issn         = {0167-7764},
  keyword      = {Critical supersaturation,Hygroscopic growth,Particles,SOA,Solubility,Traffic exhausts},
  language     = {eng},
  number       = {4},
  pages        = {359--383},
  publisher    = {Springer},
  series       = {Journal of Atmospheric Chemistry},
  title        = {Effect of solubility limitation on hygroscopic growth and cloud drop activation of SOA particles produced from traffic exhausts},
  url          = {http://dx.doi.org/10.1007/s10874-018-9380-5},
  volume       = {75},
  year         = {2018},
}