Comparing aerosol sources in a metallurgy city: Evidence from low molecular weight organic acids in PM2.5 between 2012–2013 and 2021–2022

Abstract

Understanding the decadal evolution of atmospheric pollutants is essential for evaluating environmental policies and their impact on air quality. This study examines changes in low molecular weight (LMW) dicarboxylic acids (diacids) and related compounds in PM2.5 from 2012 –2013 to 2021–2022 in Huangshi, a metallurgy city in China. PM2.5 and associated organic components, including total carbon (TC), LMW diacids, and α-dicarbonyls were halved over the decade. However, seasonal trends of diacids relative to TC remained similar, suggesting that anthropogenic, and biogenic emission activities and oxidation processes still strongly influence on organic species in the local PM2.5. During more recent years, we found increased relative abundances of short-chain diacids and related species (oxalic, malonic, succinic, glyoxylic, and pyruvic acids) in TC, whereas those of phthalic, terephthalic, adipic, azelaic, 9-oxononanoic acids and α-dicarbonyls decreased. These comparisons provide the first evidence for the decadal development of environmental policy, which caused a significant source change from anthropogenic to biogenic emissions along with photochemical aging of organic aerosols. We also suggest climate-related changes, including increased UV irradiation and ozone formation, resulting in an enhanced atmospheric oxidizing capability. This study will be useful for policymakers for the improvement of air quality and its outcomes in mining cities.