Diesel soot aging in urban plumes within hours under cold dark and humid conditions

Research output: Contribution to journalArticle

Abstract

Fresh and aged diesel soot particles have different impacts on climate and human health. While fresh diesel soot particles are highly aspherical and non-hygroscopic, aged particles are spherical and hygroscopic. Aging and its effect on water uptake also controls the dispersion of diesel soot in the atmosphere. Understanding the timescales on which diesel soot ages in the atmosphere is thus important, yet knowledge thereof is lacking. We show that under cold, dark and humid conditions the atmospheric transformation from fresh to aged soot occurs on a timescale of less than five hours. Under dry conditions in the laboratory, diesel soot transformation is much less efficient. While photochemistry drives soot aging, our data show it is not always a limiting factor. Field observations together with aerosol process model simulations show that the rapid ambient diesel soot aging in urban plumes is caused by coupled ammonium nitrate formation and water uptake.

Details

Authors
Organisations
External organisations
  • University of Oslo
  • University of Helsinki
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Environmental Sciences
  • Meteorology and Atmospheric Sciences
Original languageEnglish
Article number12364
JournalScientific Reports
Publication statusPublished - 2017 Sep 28
Publication categoryResearch
Peer-reviewedYes