Diurnal and temporal variations of water-soluble dicarboxylic acids and related compounds in aerosols from the northern vicinity of Beijing: Implication for photochemical aging during atmospheric transport

Abstract

Abstract:Aerosol samples were collected in autumn 2007 on day-and nighttime basis in the northern receptor site of Beijing, China. The samples were analyzed for total carbon (TC) and water-soluble dicarboxylic acids (C 2 -C 12 ), oxocarboxylic acids (C 2 -C 9 ), glyoxal and methylglyoxal to better understand the photochemical aging of organic aerosols in the vicinity of Beijing. Concentrations of TC are 50% greater in daytime when winds come from Beijing than in nighttime when winds come from the northern forest areas. Most diacids showed higher concentrations in daytime, suggesting that the organics emitted from the urban Beijing and delivered to the northern vicinity in daytime are subjected to photo-oxidation to result in diacids.However, oxalic acid (C 2 ), which is the most abundant diacid followed by C 3 or C 4 , became on average 30% more abundant in nighttime together with azelaic, ω-oxooctanoic and ω-oxononanoic acids, which are specific oxidation products of biogenic unsaturated fatty acids.Methylglyoxal, an oxidation product of isoprene and a precursor of oxalic acid, also became 29% more abundant in nighttime. Based on a positive correlation between C 2 and glyoxylic acid (ωC 2 ) in nighttime when relative humidity significantly enhanced, we propose a nighttime aqueous phase production of C 2 via the oxidation of ωC 2 . We found an increase in the contribution of diacids to TC by 3 folds during consecutive clear days. This study demonstrates that diacids and related compounds are largely produced in the northern vicinity of Beijing via photochemical processing of organic precursors emitted from urban center and forest areas.

Diurnal variations of carbonaceous components, major ions, and stable carbon and nitrogen isotope ratios in suburban aerosols from northern vicinity of Beijing

“…The average temperature and relative humidity at Mangshan were 25 C and 57% in daytime and 17 C and 78% in nighttime. The dominant wind pattern was characterized by southwesterly wind (205 , on average) during daytime and northeasterly wind (30 , on average) during nighttime, being consistent mostly with air mass back trajectories (He et al, 2014). Rainfall was observed at night of September 17, evening of September 26, and daytime of Oct 1.…”

“…Another possibility may be a large production of SOA by photochemical processing during the transport from the industrial area of Beijing to Mangshan site in daytime. Interestingly, He et al (2014) reported increased concentrations of dicarboxylic acids, which may serve as markers of photochemical production, and related compounds in daytime during the same campaign. The production of dicarboxylic acids and related compounds in photochemical process should contribute to the increase of OC/EC ratios in daytime.…”

“…With continuous economic growth, air quality in Beijing has been deteriorating seriously (Cao et al, 2014;Yu et al, 2013). However, our recent study on dicarboxylic acids in the ambient aerosols from background vicinity site (Mangshan) of Beijing demonstrated that their concentrations were much higher than those previously reported in Beijing (He et al, 2014). Here, we present comprehensive data sets on OC, EC, WSOC, major ions, and stable carbon and nitrogen isotopes in the ambient aerosols from Mangshan site.…”

Molecular distribution and compound-specific stable carbon isotopic composition of dicarboxylic acids, oxocarboxylic acids and <i>α</i>-dicarbonyls in PM<sub>2.5</sub> from Beijing, China

“…Except for ωC 7 and ωC 8 , the oxoacids showed larger concentrations in cold seasons (autumn and winter), which might be attributed to accumulation under stagnant meteorological conditions. Their concentrations were higher than those in aerosols from Tanzania (60.0 ± 19.0 and 31.0 ± 18.0 ng m −3 in PM 2.5 during dry and wet seasons, respectively; Mkoma and Kawamura, 2013) but much lower than these detected in Mangshan, a rural site in Beijing (159 ng m −3 in the daytime, 97.9 ng m −3 in the nighttime; He et al, 2014).…”

Residence time analysis of photochemical buildup of ozone in central eastern China from surface observation at Mt. Tai, Mt. Hua, and Mt. Huang in 2004

“…Some ozone data from regional GAW sites and Chinese EPA site have been reported (Chan et al 2002;Cheung and Wang 2001;Wang et al 2001Wang et al , 2006Zhu et al 2004). In the recent years, however, more data and analysis from both long-term and intensive campaign studies in China became available (Gao et al 2005;He et al 2014;Kanaya et al 2009Kanaya et al , 2013Li et al 2008;Lin et al 2008Lin et al , 2011Meng et al 2009;Xu et al 2008Xu et al , 2011.…”