Spatial and temporal distribution characteristics of VOCs in the Pearl River Delta region using HYSPLIT model

Based on the long time observation of VOCs at Guangdong Atmospheric Supersite (GAS) in the four seasons of 2016, 2142 sets of valid data were obtained. Using HYSPLIT model, the spatial and temporal distribution characteristics of VOCs in the Pearl River Delta region were analyzed. Mixing ratios and chemical reactivities of VOCs had obvious seasonal variation characteristics. The average concentration of VOCs was (18.523±20.978)×10-9 during the observation period. Though the mixing ratios of C2~C5 alkenes and BTEX accounted for only 46%, they contributed 85% of ∙OH loss rate (LOH), 82% of Ozone Formation Potential (OFP) and 97% of Secondary Oragnic Aerosol Formation Potential (SOAFP). The observation sites were mainly affected by the air masses from the northern inland areas (1#), the western inland areas (2#), the southern tip of the Taiwan Strait (3#) and the southern marine areas (4#). The mixing ratios of alkynes and BTEX of 1# air masses were both the highest, respectively, 10% and 37%, and the concentration of C2~C5 alkanes of 3# air masses was the highest, reaching (8.437±5.561)×10-9. By estimating the chemical reactivities of VOCs of air masses, it was found that the chemical reactivities of VOCs of 1# air masses were the strongest, and their contributions to O3 and SOA production were the highest. The chemical reactivities of VOCs of air masses of 1#, 2#, 3# and 4# were mainly contributed by BTEX and C2~C5 alkenes. © 2020, Editorial Board of China Environmental Science. All right reserved.