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

Summary, in English

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.

• Author: Axel Eriksson; Cerina Wittbom; Pontus Roldin; Moa Sporre; Emilie Öström; Patrik Nilsson; Johan Martinsson; Jenny Rissler; ERIK NORDIN; Birgitta Svenningsson; Joakim Pagels; Erik Swietlicki
• Department/s: Ergonomics and Aerosol Technology; Nuclear physics; Centre for Environmental and Climate Science (CEC); MERGE: ModElling the Regional and Global Earth system
• Publishing year: 2017-09-28
• Language: English
• Publication/Series: Scientific Reports
• Links: http://dx.doi.org/10.1038/s41598-017-12433-0
• Document type: Journal article
• Publisher: Nature Publishing Group
• Topic: Environmental Sciences; Meteorology and Atmospheric Sciences
• Status: Published
• ISBN/ISSN/Other: ISSN: 2045-2322