Enhanced aqueous-phase formation of secondary organic aerosols due to the regional biomass burning over North China Plain

Seasonal variation and secondary formation of size-segregated aerosol water-soluble inorganic ions in a coast megacity of North China Plain

“…These results indicated that the particles were alkaline in the coarse mode in all seasons, especially in the spring. It should be noted that organic acids and carbonic acid which abundant in biomass burning aerosols in NCP (Wang et al 2020) were not measured in this study thus resulting in high CE/AE ratios due to the absence of anions, especially in spring and autumn. These ratios were close to those observed at the background station (Shangdianzi) in the Beijing-Tianjin-Hebei region (Yang et al 2017), indicating that the acid-base balance of particulate matter in this region may follow a similar pattern.…”

Large contribution of fossil-derived components to aqueous secondary organic aerosols in China

“…The uptake of water-soluble gaseous organic precursors to wet aerosol particles and fog/clouds, with subsequent aqueous-phase transformation to lower volatile compounds could be a signi cant pathway for WSOC aerosol formation 23,26,30,31 . Given the high relative humidity (RH%) (74 ± 9%; Supplementary Table 2) and the abundant hygroscopic particles (particularly for particulate nitrate as shown in Supplementary Fig.…”

“…Given the high relative humidity (RH%) (74 ± 9%; Supplementary Table 2) and the abundant hygroscopic particles (particularly for particulate nitrate as shown in Supplementary Fig. 4) in our continental out ow samples, we expect that the changes in the gas-particle partitioning driven by the increased ALW could have enhanced the formation of aqSOA species, such as oxalic acid 23,26,32 . This can be supported by the sixfold higher aqSOA precursors (Gly + MeGly) mass fractions in OC observed in the continental out ow samples than the coastal background (Supplementary Table 4).…”

“…The technique was applied to puri ed oxalic acid and other similarly abundant organic acids (e.g., glyoxylic acid). Oxalic acid, likely represent the highest oxidation states of OA, has frequently been used as a proxy for aqueous processing in both laboratory and eld studies [21][22][23] . Organic acids that have high O/C ratios (around 1−2), are among the most abundant SOA components and are key end products in the aqueous-phase photochemical oxidation of various volatile organic compounds (VOCs) and intermediates such as glyoxal (Gly) and methylglyoxal (MeGly) in clouds or wet aerosols 4,5,24,25 .…”

“…Organic acids that have high O/C ratios (around 1−2), are among the most abundant SOA components and are key end products in the aqueous-phase photochemical oxidation of various volatile organic compounds (VOCs) and intermediates such as glyoxal (Gly) and methylglyoxal (MeGly) in clouds or wet aerosols 4,5,24,25 . Therefore, these organic acids can serve as signature compounds to trace the aqSOA formation pathways [21][22][23]26 .…”