Impact of anthropogenic emissions on biogenic secondary organic aerosol: Observation in the Pearl River Delta, South China

Yu-Qing Zhang, Duo-Hong Chen, Xiang Ding, Jun Li, Tao Zhang, Jun-Qi Wang, Qian Cheng, Hao Jiang, Wei Song, Yu-Bo Ou, Peng-Lin Ye, Gan Zhang (+1 others)
2019 Atmospheric Chemistry and Physics Discussions  
<p><strong>Abstract.</strong> Secondary organic aerosol (SOA) formation from biogenic precursors is affected by anthropogenic emissions, which is not well understood in polluted areas. In the study, we accomplished a year-round campaign at nine sites in the polluted areas located in Pearl River Delta (PRD) region during 2015. We measured typical biogenic SOA (BSOA) tracers from isoprene, monoterpenes, and <i>&amp;beta;</i>-caryophyllene as well as major gaseous and particulate pollutants and
more » ... e pollutants and investigated the impact of anthropogenic pollutants on BSOA formation. The concentrations of BSOA tracers were in the range of 45.4 to 109&amp;thinsp;ng&amp;thinsp;m<sup>&amp;minus;3</sup> with the majority composed of products from monoterpenes (SOA<sub>M</sub>, 47.2&amp;thinsp;&amp;plusmn;&amp;thinsp;9.29&amp;thinsp;ng&amp;thinsp;m<sup>&amp;minus;3</sup>), followed by isoprene (SOA<sub>I</sub>, 23.1&amp;thinsp;&amp;plusmn;&amp;thinsp;10.8&amp;thinsp;ng&amp;thinsp;m<sup>&amp;minus;3</sup>), and <i>&amp;beta;</i>-caryophyllene (SOA<sub>C</sub>, 3.85&amp;thinsp;&amp;plusmn;&amp;thinsp;1.75&amp;thinsp;ng&amp;thinsp;m<sup>&amp;minus;3</sup>). We found that atmospheric oxidants, O<sub><i>x</i></sub> (O<sub>3</sub> plus NO<sub>2</sub>), and sulfate correlated well with high-generation SOA<sub>M</sub> tracers, but not so for first-generation SOA<sub>M</sub> products. This suggested that high O<sub><i>x</sub></i> and sulfate could promote the formation of high-generation SOA<sub>M</sub> products, which probably led to relatively aged SOA<sub>M</sub> we observed in the PRD. For the SOA<sub>I</sub> tracers, not only 2-methylglyceric acid (NO/NO<sub>2</sub>-channel product), but also the ratio of 2-methylglyceric acid to 2-methyltetrols (HO<sub>2</sub>-channel products) exhibit NO<sub><i>x</i></sub> dependence, indicating the significant impact of NO<sub><i>x</i></sub> on SOA<sub>I</sub> formation pathways. The SOA<sub>C</sub> tracer elevated in winter at all sites and positively correlated with levoglucosan, O<sub><i>x</sub></i>, and sulfate. Thus, the unexpected increase of SOA<sub>C</sub> in wintertime might be highly associated with the enhancement of biomass burning, atmospheric oxidation capacity and sulfate components in the PRD. The BSOAs that were estimated by the SOA tracer approach showed the highest concentration in fall and the lowest concentration in spring with an annual average concentration of 1.68&amp;thinsp;&amp;plusmn;&amp;thinsp;0.40&amp;thinsp;&amp;mu;g&amp;thinsp;m<sup>&amp;minus;3</sup>. SOA<sub>M</sub> dominated the BSOA mass all year round. We also found that BSOA correlated well with sulfate and O<sub><i>x</i></sub>. This implicated the significant effects of anthropogenic pollutants on BSOA formation and highlighted that we could reduce the BSOA through controlling on the anthropogenic emissions of sulfate and O<sub><i>x</sub></i> precursors in polluted regions.</p>
doi:10.5194/acp-2019-559 fatcat:wxqtjvy42fairjqdvai4lxauaq