Distribution characteristics, source apportionment, and chemical reactivity of volatile organic compounds in two adjacent areas in Shanxi, North China

To determine the pollution characteristics, source apportionment, and chemical reactivity of volatile organic compounds (VOCs) in two adjacent areas, VOC samples were collected using 3.2-L stainless steel canisters between 2017 and 2018 in Taiyuan and Yuci areas. The concentrations of 48 VOCs were determined using a gas chromatography-mass selective detector/flame ionization detector. The average concentrations of the 48 VOCs (total VOCs [TVOCs]) in the Taiyuan and Yuci areas were 30.09 and 24.08 ppbv, respectively; the highest concentrations were recorded for ethane, which accounted for 21.40% and 25.49% of the TVOCs detected in the Taiyuan and Yuci areas, respectively. Alkanes accounted for the highest proportion of the TVOCs, followed by alkenes, alkynes, and aromatics. Through positive matrix factorization, six source categories were identified in Taiyuan and Yuci, namely gasoline evaporation (24.38%), petrochemical industrial sources (15.46%), biogenic emissions and LPG usage (8.75%), combustion sources (28.33%), solvent use (12.95%), and vehicle exhaust (10.13%). The backward trajectory and weighted potential source contribution function analysis results indicated that Taiyuan and Yuci were potential source areas for each other in September, and that Taiyuan was the potential source area of Yuci in November and December. Among the TVOCs detected in the Taiyuan and Yuci areas, alkenes contributed the most to ozone formation potential (OFP), followed by aromatics and alkanes; alkynes contributed the least to OFP. Aromatics contributed the most to secondary organic aerosol formation potential (SOAFP), accounting for 92.80% and 92.37% of the SOAFP in the Taiyuan and Yuci areas, respectively. These results indicate that the TVOCs in the Taiyuan and Yuci areas must be controlled, particularly aromatics with high SOAFP and alkenes with high OFP. Our results help to clarify the migration, transformation, and sources of ambient VOCs in adjacent areas; they also provide fundamental data on pollution control and the prevention of regional organic air pollution.