Strong anthropogenic control of secondary organic aerosol formation from isoprene in Beijing

Abstract

Isoprene-derived secondary organic aerosol (iSOA) is a significant contributor to organic carbon (OC) in some forested regions, such as tropical rainforests and the Southeast US. However, its contribution to organic aerosol in urban areas, with high levels of anthropogenic pollutants, is poorly understood. In this study we examined the formation of anthropogenic-influenced iSOA during summer in Beijing, China. Local isoprene emissions and high levels of anthropogenic pollutants, in particular NOX and particulate SO4 2-, led to the formation of iSOA under both high- and low-NO oxidation conditions, with significant heterogeneous transformations of isoprene-derived oxidation products to particulate organosulfates (OSs) and nitrooxy-organosulfates (NOSs). Ultra-pressure liquid chromatography coupled to high-resolution mass spectrometry was combined with a rapid automated data processing technique to quantify 31 proposed iSOA tracers in offline PM2.5 filter extracts. The coelution of the inorganic ions in the extracts caused matrix effects that impacted two authentic standards differently. The average concentration of iSOA OSs and NOSs was 82.5 ng m-3, around three times higher than the observed concentrations of their oxygenated precursors (2-methyltetrols and 2- methylglyceric acid). OS formation was dependant on both photochemistry and sulfate available for reactive uptake as shown by a strong correlation with the product of ozone (O3) and particulate sulfate (SO4 2-). A greater proportion of high-NO OS products were observed in Beijing compared to previous studies in less polluted environments. The iSOA derived OSs and NOSs represented on average 0.62 % of the oxidised organic aerosol measured by aerosol mass spectrometry, but this increased to ~3 % on certain days. These results indicate for the first time that iSOA formation in urban Beijing is strongly controlled by anthropogenic emissions and results in extensive conversion to heterogeneous OS products.

Publication DOI: https://doi.org/10.5194/acp-2019-929
Divisions: Engineering & Applied Sciences > Chemical Engineering & Applied Chemistry
Additional Information: © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License.
Full Text Link:
Related URLs: https://www.atm ... t/20/7531/2020/ (Publisher URL)
PURE Output Type: Article
Published Date: 2020-06-30
Accepted Date: 2020-05-15
Submitted Date: 2019-10-23
Authors: Bryant, Daniel J.
Dixon, William J.
Hopkins, James R.
Dunmore, Rachel E.
Pereira, Kelly L.
Shaw, Marvin
Squires, Freya A.
Bannan, Thomas J.
Mehra, Archit
Worrall, Stephen D. ( 0000-0003-1969-3671)
Bacak, Asan
Coe, Hugh
Percival, Carl J.
Whalley, Lisa K.
Heard, Dwayne E.
Slater, Eloise J.
Ouyang, Bin
Cui, Tianqu
Surratt, Jason D.
Liu, Di
Shi, Zongbo
Harrison, Roy
Sun, Yele
Xu, Weiqi
Lewis, Alastair C.
Lee, James D.
Rickard, Andrew R.
Hamilton, Jacqueline F.

Download

[img]

Version: Draft Version

License: Creative Commons Attribution

| Preview

[img]

Version: Published Version

License: Creative Commons Attribution

| Preview

Export / Share Citation


Statistics

Additional statistics for this record