Premium
Direct atmospheric evidence for the irreversible formation of aqueous secondary organic aerosol
Author(s) -
ElSayed Marwa M. H.,
Wang Yingqing,
Hennigan Christopher J.
Publication year - 2015
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 - 10.1002/2015gl064556
Subject(s) - aerosol , relative humidity , total organic carbon , evaporation , particle (ecology) , aqueous solution , chemistry , environmental chemistry , aqueous two phase system , atmospheric sciences , meteorology , organic chemistry , physics , geology , oceanography
The reversible nature of aqueous secondary organic aerosol (aqSOA) formation was characterized for the first time through direct atmospheric measurements. Water‐soluble organic carbon in the gas and particle phases (WSOC g and WSOC p ) was measured simultaneously to quantify aqSOA formation in Baltimore, Maryland. During the nighttime, aqSOA formation was evident as WSOC g increasingly partitioned to the particle phase with increasing relative humidity (RH). To characterize the reversible/irreversible nature of this aqSOA, the WSOC p measurement was alternated through an unperturbed ambient channel and through a “dried” channel maintained at ~40% RH (with 7 s residence time) to mimic the natural drying particles undergo throughout the day. Across the entire RH range encountered, there was no statistically significant difference in WSOC p concentrations through the dry and ambient channels, indicating that the aqSOA remained in the condensed phase upon the evaporation of aerosol water. This strongly suggests that the observed aqSOA was formed irreversibly.