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Published December 18, 2012 | Supplemental Material + Published
Journal Article Open

Equilibration timescale of atmospheric secondary organic aerosol partitioning


[1] Secondary organic aerosol (SOA) formed from partitioning of oxidation products of anthropogenic and biogenic volatile organic compounds (VOCs) accounts for a substantial portion of atmospheric particulate matter. In describing SOA formation, it is generally assumed that VOC oxidation products rapidly adopt gas-aerosol equilibrium. Here we estimate the equilibration timescale, τ_(eq), of SOA gas-particle partitioning using a state-of-the-art kinetic flux model. Τ_(eq) is found to be of order seconds to minutes for partitioning of relatively high volatility organic compounds into liquid particles, thereby adhering to equilibrium gas-particle partitioning. However, τ_(eq) increases to hours or days for organic aerosol associated with semi-solid particles, low volatility, large particle size, and low mass loadings. Instantaneous equilibrium partitioning may lead to substantial overestimation of particle mass concentration and underestimation of gas-phase concentration.

Additional Information

© 2012 American Geophysical Union. Received 25 September 2012; revised 30 October 2012; accepted 6 November 2012; published 18 December 2012. This work was supported by National Science Foundation grant AGS-1057183. MS is supported by the Japan Society for the Promotion of Science (JSPS) Postdoctoral Fellowship for Research Abroad. The authors thank Andreas Zuend, Xi Zhang and Ulrich Pöschl for helpful discussions. The Editor thanks two anonymous reviewers for their assistance in evaluating this paper.

Attached Files

Published - grl29822.pdf

Supplemental Material - FigureS1.jpg

Supplemental Material - Table1.txt

Supplemental Material - TextS1.doc

Supplemental Material - grl29822-sup-0001-readme.txt


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