Sources and Formation Processes of Short-Chain Saturated Diacids (C2–C4) in Inhalable Particles (PM10) from Huangshi City, Central China

Abstract

PM 10 samples were collected from Huangshi (HS) city, Central China during April 2012 to March 2013, and were analyzed for short-chain saturated dicarboxylic acids (diacids) using a capillary gas chromatograph (GC). We found that oxalic acid (C 2 , 318 ± 104 ng·m −3 ) was the most abundant diacid species, followed by malonic acid (C 3 , 25.4 ± 9.11 ng·m −3 ) and succinic acid (C 4 , 2.09 ± 0.52 ng·m −3 ). The concentrations of C 2 and C 4 diacids were highest in winter, followed by summer and spring, and lowest in autumn. C 3 diacid was decreased in the order of summer > winter > autumn > spring. Further, the seasonal variations of WSOC (water-soluble organic carbon)-and OC (organic carbon)-normalized diacid concentrations were similar to those of diacid concentrations, suggesting that both primary emission and secondary production are important sources for diacids in Huangshi (HS) aerosols. Strong correlations were found among C 2 diacid and the three ions SO 4 2− , NO 3 − , and NH 4 + in summer and winter, suggesting that the species could undergo a similar secondary oxidation processing. C 2 had good correlation with K + in summer and autumn, which indicates an enhanced contribution of combustion sources for C 2 diacid. Moreover, according to the ratio of C 2 /K + , we can conclude that C 2 diacid should be formed by a secondary reaction of biomass combustion in HS aerosols, especially in summer and autumn. The ratios of C 2 /C 4 and C 3 /C 4 were compared with those reported in other sites, and the results suggest that HS aerosols should be more photochemically aged than at other urban areas. Principal component analysis of diacids and selected water-soluble inorganic ions over four seasons suggests that HS aerosols are influenced not only from primary emission, but also from secondary reaction. According to the linear relation between C 2 and C 3 diacids, the results indicate that C 2 diacid is formed from the oxidation of hydrocarbon compounds in spring, while it is from the oxidation of C 3 and C 4 diacids in summer, autumn, and winter.

Dicarboxylic acids and related compounds in fine particulate matter aerosols in Huangshi, central China

“…Coal is the dominant fuel for electricity generation, domestic cooking and heating, and industrial processes. Suspended particulate matter (PM) is the main pollutant that affects air quality and human health (Liu et al 2017;Zhan et al 2016;Zhang et al 2015). In this study, PM 2.5 samples were collected in HS from March 2012 to February 2013 and quantified by gas chromatography (GC).…”