Investigation of the influences of anthropogenic emissions on isoprene-derived secondary organic aerosol formation during the 2013 Southern Oxidant & Aerosol Study at the Birmingham, AL ground site

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Chu, Kevin
- Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering

Abstract

Fine particulate matter (PM2.5) impacts public health, air quality and global climate. In the southeastern U.S., emissions of isoprene from deciduous trees undergo atmospheric oxidation to form secondary organic aerosol (SOA) that contributes to PM2.5. To examine how anthropogenic pollutants influence isoprene-derived SOA formation, PM2.5 filter samples taken at the Birmingham, AL ground site during the 2013 Southern Oxidant and Aerosol Study were analyzed by gas chromatography/electron impact-mass spectrometry for known isoprene SOA tracers. Tracers were compared with collocated measurements of anthropogenic and meteorological variables. On average, isoprene-derived SOA contributed 7.1% (up to ~22%) of total fine organic aerosol mass. Isoprene-SOA correlated with sulfate (r2 = 0.34) and acidity (r2 = 0.24), but not with oxides of nitrogen (NOx). Ozone (O3) correlated with MAE/HMML-derived tracers (r2 = 0.31) and with 2-methyltetrols (r2 = 0.16), phenomena not previously observed in field studies. These results demonstrate that anthropogenic pollutants enhance isoprene-derived SOA formation.

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