Characteristics and Potential Sources of Four Ozone Pollution Processes in Hainan Province in Autumn of 2019

Abstract

Based on the air quality and meteorological monitoring data of Hainan province in autumn of 2019, this study analyzed the characteristics and potential sources for the four O3 polluted processes in Hainan province, using the methods of correlation analysis, HYSPLIT backward trajectory modeling, PSCF (potential source contribution function), and CWT (concentration weighted-trajectory). The results showed that ① the average concentrations of the maximum 8h average (O3-8h) for process 1 and process 3, which occurred from September 21st to 30th and November 3rd to 11th with the durations of 10 d and 9 d, were 145.52 μg·m-3 and 143.55 μg·m-3, respectively. Process 2 and process 4 occurred from October 18th to 21st and November 20th to 25th, with the durations of 4 d and 6 d, and the average concentrations of O3-8h were 130.79 μg·m-3 and 115.46 μg·m-3, respectively. ② High air pressure, low precipitation and relative humidity, long sunshine duration, and strong solar radiation favored the occurrence of O3-polluted weather in Hainan province. Northerly wind was conducive to the increase in O3-8h concentration, and wind speeds affected the regional distribution of high-value areas of O3-8h concentration in Hainan province. ③ Furthermore, process 1 and process 3 with more serious pollution had a larger air flow divergence, and there were two airflows originating from the inland area and the southeast coastal area, respectively. Air flow of process 2 and process 4 was relatively more concentrated with less O3 pollution and was classified as southeast coastal air flow. 4 The analysis of potential contribution sources showed that transport from Zhejiang, Jiangxi, Fujian, and Guangdong provinces were the main sources of O3 pollution in Hainan province in autumn 2019. Among them, the weight potential source contribution function (WPSCF) and weight concentration weighted-trajectory (WCWT) values were larger than 0.36 and 90 μg·m-3 in the PRD (Pearl River Delta) and western Guangdong province regions, respectively.