Open AccessCloud Processing of Secondary Organic Aerosol from Isoprene and Methacrolein Photooxidation
Author(s) -
Chiara Giorio,
Anne Monod,
L. Brégonzio-Rozier,
H. Langley DeWitt,
Mathieu Cazaunau,
Brice Temime-Roussel,
Aline Gratien,
Vincent Michoud,
Edouard Pangui,
Sylvain Ravier,
Arthur T. Zielinski,
Andrea Tapparo,
Reinhilde Vermeylen,
Magda Claeys,
Didier Voisin,
Markus Kalberer,
JeanFrançois Doussin
Publication year - 2017
Publication title -
the journal of physical chemistry. a/the journal of physical chemistry. a.
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.756
H-Index - 235
eISSN - 1520-5215
pISSN - 1089-5639
DOI - 10.1021/acs.jpca.7b05933
Subject(s) - methacrolein , isoprene , aerosol , cloud condensation nuclei , chemistry , mass spectrometry , relative humidity , evaporation , particle (ecology) , analytical chemistry (journal) , environmental chemistry , meteorology , organic chemistry , chromatography , polymer , physics , oceanography , monomer , geology , copolymer , methacrylic acid
Aerosol-cloud interaction contributes to the largest uncertainties in the estimation and interpretation of the Earth's changing energy budget. The present study explores experimentally the impacts of water condensation-evaporation events, mimicking processes occurring in atmospheric clouds, on the molecular composition of secondary organic aerosol (SOA) from the photooxidation of methacrolein. A range of on- and off-line mass spectrometry techniques were used to obtain a detailed chemical characterization of SOA formed in control experiments in dry conditions, in triphasic experiments simulating gas-particle-cloud droplet interactions (starting from dry conditions and from 60% relative humidity (RH)), and in bulk aqueous-phase experiments. We observed that cloud events trigger fast SOA formation accompanied by evaporative losses. These evaporative losses decreased SOA concentration in the simulation chamber by 25-32% upon RH increase, while aqueous SOA was found to be metastable and slowly evaporated after cloud dissipation. In the simulation chamber, SOA composition measured with a high-resolution time-of-flight aerosol mass spectrometer, did not change during cloud events compared with high RH conditions (RH > 80%). In all experiments, off-line mass spectrometry techniques emphasize the critical role of 2-methylglyceric acid as a major product of isoprene chemistry, as an important contributor to the total SOA mass (15-20%) and as a key building block of oligomers found in the particulate phase. Interestingly, the comparison between the series of oligomers obtained from experiments performed under different conditions show a markedly different reactivity. In particular, long reaction times at high RH seem to create the conditions for aqueous-phase processing to occur in a more efficient manner than during two relatively short cloud events.