Molecular Distribution, Seasonal Variations, and Sources of Typical Polar Organics in PM_2.5 from Jinzhong, China

Abstract

Polar organics are essential constituents in atmospheric aerosols, but few studies have analyzed their distribution characteristics and sources. In this study, 42 typical polar organics, including 10 aromatic acids, 9 aliphatic dibasic acids, 3 anhydrosugars, 14 sugars and sterols, and 6 fatty acids in PM 2.5 in Jinzhong, China, were analyzed. Their annual average concentrations were 0. 07− 11.1, 0.24−5.30, 2.33−38.1, 0.06−10.5, and 0.40−22.2 ng/m 3 , respectively, with the most abundant compounds being p-phthalic acid, succinic acid, levoglucosan, glycerol, and palmitic acid, respectively. For anhydrosugars, aliphatic dibasic acids, and sugars and sterols, the highest concentrations were found in winter, summer, and spring, respectively. However, the concentrations of aromatic acids from both the primary source and secondary photochemical formation were higher in autumn (36.1%) and winter (35.6%) than in other seasons, whereas fatty acids exhibited no obvious seasonal differences. Two anhydrosugars (mannosan and galactosan), six aromatic acids (m-, p-phthalic acid, and four phenolic acids), and four sugars and sterols (erythritol, glycerol, xylitol, and xylose) were highly correlated with levoglucosan, indicating their association with biomass burning. The levoglucosan/ mannosan and mannosan/galactosan ratios indicated that the types of biomass burning in Jinzhong were crop straw, hardwood, and pine needles. By contrast, three aromatic acids (o-phthalic acid and 1,2,3-and 1,2,4-benzene-tricarboxylic acid), three aliphatic dibasic acids (succinic, glutaric, and adipic acid), and glyceric acid all had a certain correlation with SO 4 2− , indicating their secondary photochemical formation. The values of o-phthalic acid/azelaic acid revealed that the anthropogenic precursor had a higher contribution to secondary formation. Principal component analysis revealed that the potential sources of polar organics in PM 2.5 included biomass burning (32.8%), anthropogenic secondary organic aerosols (21.5%), biogenic primary and secondary organic aerosols (18.7%), and soil dust (11.5%).

Origins of Particulate Organic Acids during High-Altitude Transport over the North China Plain: Results from Mount Tai and a Flight Campaign in Winter 2019

“…The initialization of aerosol composition measurements of PM 2.5 data alongside the trajectory derived from an extensive literature screening was used (Table S6). ,,− As these averaged PM 2.5 concentrations reflect ground measurements, they were also scaled to the height of the trajectory (factor of 4.5). The aerosol distribution was assumed to be monomodal, and the initialized composition was derived from the mass fractions of individual compounds using averaged values from different stations.…”

Molecular signatures of organic particulates as tracers of emission sources

“…Many chemicals are carbohydrate molecules (e.g., glucose, xylose, and sucrose) and the respective dehydration-polymerization by-products of them (levoglucosan, galactosan, mannosan, inositols) (Simoneit et al 2004 ; Jia and Fraser 2011 ; Pereira et al 2017 ; Bikkina et al 2019 ; Lv et al 2021 ) and of lignin (e.g., methoxyphenols) (Hawthorne et al 1988 ; Hays et al 2005 ). Levoglucosan is usually the predominant anhydrosugar; however, other minor polysaccharides allow distinguishing hardwood from softwood burning, thanks to their concentration ratios vs. levoglucosan; in fact, levoglucosan/mannosan ratios ranging from 3 to 10 are typical combustion of softwood, while ratios ranging 15 ÷ 25 of hardwood, and > 40 of crop burning (Kang et al 2018 ; Mu et al 2021 ). Levoglucosan in particular, typical tracer of wood burning, allowed to demonstrate that even the downtowns of big cities undergo the impact of this kind of emission, due to the generalized use of wood for heating and cooking in the countryside (Fine et al 2004 ).…”

Impact Assessment of Heavy Metals in PM2.5 of Indoor Dust in Xi'an, China

“…In addition to affecting air quality, haze pollution could have serious negative impacts on atmospheric visibility, climate, economic and social development, and human health. (Mu et al, 2021;Wang et al, 2022) Fine particulate matter (PM 2.5 , particulate matter with an aerodynamic diameter of < 2.5 µm) has been shown to be the main factor in the formation of haze pollution. (Li et al, 2022) Owing to the small particle size and large speci c surface area of PM2.5, it can absorb toxic substances (such as organic pollutants and heavy metals) and remain in the atmosphere for a long time.…”