Changes of hygroscopicity and morphology during ageing of diesel soot

Torsten Tritscher, Zsófia Jurnyi, Maria Martin, Roberto Chirico, Martin Gysel, Maarten F Heringa, Peter F Decarlo, Berko Sierau, André S H Prévt, Ernest Weingartner, Urs Baltensperger

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Soot particles are an important component of atmospheric aerosol and their interaction with water is important for their climate effects. The hygroscopicity of fresh and photochemically aged soot and secondary organic aerosol (SOA) from diesel passenger car emissions was studied under atmospherically relevant conditions in a smog chamber at sub-and supersaturation of water vapor. Fresh soot particles show no significant hygroscopic growth nor cloud condensation nucleus (CCN) activity. Ageing by condensation of SOA formed by photooxidation of the volatile organic carbon (VOC) emission leads to increased water uptake and CCN activity as well as to a compaction of the initially non-spherical soot particles when exposed to high relative humidity (RH). It is important to consider the latter effect for the interpretation of mobility based measurements. The vehicle with oxidation catalyst (EURO3) emits much fewer VOCs than the vehicle without after-treatment (EURO2). Consequently, more SOA is formed for the latter, resulting in more pronounced effects on particle hygroscopicity and CCN activity. Nevertheless, the aged soot particles did not reach the hygroscopicity of pure SOA particles formed from diesel VOC emissions, which are similarly hygroscopic (0.06 < κH - TDMA < 0.12 and 0.09 < κCCN < 0.14) as SOA from other precursor gases investigated in previous studies. © 2011 IOP Publishing Ltd.
Original languageEnglish
Article number034026
Pages (from-to)-
JournalEnvironmental Research Letters
Issue number3
Publication statusPublished - 2011
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Environmental Science(all)
  • Renewable Energy, Sustainability and the Environment
  • Public Health, Environmental and Occupational Health

Cite this

Tritscher, T., Jurnyi, Z., Martin, M., Chirico, R., Gysel, M., Heringa, M. F., Decarlo, P. F., Sierau, B., Prévt, A. S. H., Weingartner, E., & Baltensperger, U. (2011). Changes of hygroscopicity and morphology during ageing of diesel soot. Environmental Research Letters, 6(3), -. [034026].