US EPA

2533939 

Journal Article 

Intermediate-volatility organic compounds: a large source of secondary organic aerosol 

Zhao, Y; Hennigan, CJ; May, AA; Tkacik, DS; de Gouw, JA; Gilman, JB; Kuster, WC; Borbon, A; Robinson, AL 

2014 

1 

Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 

48 

23 

13743-13750 

English 

25375804 

10.1021/es5035188 

WOS:000345803800023 

Secondary organic aerosol (SOA) is a major component of atmospheric fine particle mass. Intermediate-volatility organic compounds (IVOCs) have been proposed to be an important source of SOA. We present a comprehensive analysis of atmospheric IVOC concentrations and their SOA production using measurements made in Pasadena, California during the California at the Nexus of Air Quality and Climate Change (CalNex) study. The campaign-average concentration of primary IVOCs was 6.3 ± 1.9 μg m(-3) (average ± standard deviation), which is comparable to the concentration of organic aerosol but only 7.4 ± 1.2% of the concentration of speciated volatile organic compounds. Only 8.6 ± 2.2% of the mass of the primary IVOCs was speciated. Almost no weekend/weekday variation in the ambient concentration of both speciated and total primary IVOCs was observed, suggesting that petroleum-related sources other than on-road diesel vehicles contribute substantially to the IVOC emissions. Primary IVOCs are estimated to produce about 30% of newly formed SOA in the afternoon during CalNex, about 5 times that from single-ring aromatics. The importance of IVOCs in SOA formation is expected to be similar in many urban environments.