AI Summary & Key Takeaways
AI InsightThe results showed that the isoprene SOA tracers exhibited the highest levels (17.64 ± 9.75 ng m-3 ) and were always observed along with higher temperatures, which results in a higher tracer formation rate and isoprene emission strength.
📌 3 Key Takeaways
Özet
To evaluate biogenic secondary organic aerosol (BSOA) tracers from biogenic precursors, fine particles (PM2.5) were collected using filter-based high-volume samplers from spring-summer of 2015 in the central part of Shanghai, China. The results showed that the isoprene SOA tracers exhibited the highest levels (17.64 ± 9.75 ng m-3 ) and were always observed along with higher temperatures, which results in a higher tracer formation rate and isoprene emission strength. However, the isoprene SOA tracers showed a weak correlation with the relative humidity (p > 0.05). The isoprene SOA tracers showed remarkable correlations with the [Hþ] because of the enhanced formation of isoprene SOA in the acidic aerosols. On the basis of these results, 2-methylglyceric acid was determined to have weak correlations with other isoprene tracers, which indicated that it had different formation pathways from those of other isoprene SOA tracers. Cis-pinonic acid had negative correlations with other SOA tracers, indicating that it is the first product in the oxidation process. Furthermore, the isoprene-based tracers (SOCisoprene) were calculated to be 0.031e0.299 mgCm3 (with an average of 0.114 ± 0.062 mgCm-3 ), which accounted for more than half of the biogenic SOA. The SOC estimation with SOA tracers (SOC tracer-based) averaged 0.155 ± 0.066 mg m-3 , with a range from 0.049 to 0.309 mg m3 during the sampling period, which amounted to 2.73% OC.