Taking Juehua Island as a Typical Example to Explore the Vertical Distribution Characteristics and Potential Sources of Air Pollutants

Juehua Island is the largest island in Liaodong Bay. Studying the distribution characteristics and potential sources of pollutants in Juehua Island has strong representative significance for studying the distribution characteristics and sources of pollutants in coastal areas. In this paper, the ground-based multi-axis differential optical absorption spectroscopy (MAX-DOAS) was performed continuously to observe the vertical profiles of aerosol, NO2 and SO2 on Juehua Island(120. 78 E, 40. 48 N) from October 2020 to June 2021. This study aims to learn the seasonal variation characteristics and potential sources of pollutant sat different altitudes. By comparing the ground-based MAX-DOAS and TROPOMI observations, we found that their variation trends are in good agreement, and the correlation coefficient is 0. 82. The observation results show that the concentration of pollutants in Juehua Island has obvious seasonality characteristics. The averaged concentrations of NO2 and SO2 in autumn and winter are 14. 5/1015 and 16. 6X 1016 molec " cm 2, respectively, which are higher than those in spring and summer of 84% and 88%. The vertical profile results show that the pollutants have obvious vertical distribution and diurnal variation characteristicsin autumn and winter. The high concentrations of NO2 mainly occurred before 10:00 and between 15:30 and 17:30 at the height layer of 0-400 m. The high concentrations of SO2 mainly occurred before 10:00 and after 16:00 at a height layer of 0-500 m. The high AODs in autumn and winter mainly appeared at 400 meters before 10: 00 and after 16: 00 and maintained high concentrations throughout the whole day in spring and summer, especially around 11:00 and after 17:00. The airmassbackward trajectory combined with the potential source analysis method. It was used to learn that the higher concentrations of NO2 and SO2 in autumn and winter were mainly affected by regional transport from industrial and vehicle emissions in the Beijing-TianjinHebei region and the ships emissions in the Liaodong Bay, and the aerosols mainly came from the biomass combustion transport of Shandong. Therefore, it can be concluded that the various characteristics of air pollutants in Juehua Island are closely related to regional transport.