Diurnal Variations of Isoprene, Monoterpenes, and Toluene Oxidation Products in Aerosols at a Rural Site of Guanzhong Plain, Northwest China

In this study, the characteristics and formation mechanism of summertime isoprene, monoterpene, toluene-derived secondary organic aerosols (SOAs) were investigated in a rural area Guanzhong Plain, Northwest China. The variations key indicators primary sources indicated significant influence biomass burning on PM2.5 during observation period. concentrations total measured SOA tracers from toluene 40.85 ± 17.31, 24.27 7.50, 10.61 0.33 ng/m3, respectively. average ratio cis-pinonic pinic acids to 3-Methyl-1,2,3-butanetricarboxylic acid (MBTCA)(P/M) 0.45 0.85 by day night, low daytime was mainly due stronger photo-degradation particle-to-gas distribution semi-volatile acids. monoterpene significantly correlated with levoglucosan at night (R2 = 0.51, p < 0.01), as > 0.67, indicating contribution combustion these SOAs. mass concentration isoprene-, monoterpenes-, SOC estimated using tracer yield method. calculated SOCs 0.25–0.71 (average: 0.46) 0.26–0.78 0.42) µgC/m3, accounting for 3.35–10.58% 3.87–13.51% OC