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Equilibration timescale of atmospheric secondary organic aerosol partitioning
Author(s) -
Shiraiwa Manabu,
Seinfeld John H.
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl054008
Subject(s) - aerosol , volatility (finance) , particle (ecology) , particulates , environmental chemistry , flux (metallurgy) , organic matter , environmental science , chemistry , organic chemistry , geology , financial economics , economics , oceanography
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.