Investigation of aerosol optical properties and pollutant transmission mechanisms in Qinhuangdao, North China – A case study during a pollution event

Abstract

In this study, the aerosol optical properties, vertical distributions, and pollutant transmission characteristics were analyzed using multi-source data during a pollution event that occurred in March 2019 in Qinhuangdao (QHD), China. During this event, the air pollutant (PM, SO2, NO2, and CO) concentrations increased by 100 μgm−3, 10 μgm−3, 40 μgm−3, and 0.7 mgm−3, respectively. The key meteorological factors were investigated and are closely related to the variations in the concentration of the pollutant. The aerosol optical depth at 500 (AOD500) measured using the Cimel Sunphotometer reached 1.6 on polluted days. Also, the water vapor content increased from 0.55 to 1.25 cm. The result of scatter plots between AOD and the Ångström exponent (AE) indicates that the primary pollutants were fine particles and small amounts of dust, showing the characteristics of mixed pollution. Furthermore, the results of the wind field and backward trajectory indicate that the pollutants with high concentrations originated from the central and northern parts of China, including Henan, Hebei, and Shandong provinces. It is revealed from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) that the pollutants were mainly mixed aerosols in the source area, and this is consistent with the results obtained from the ground-based Sunphotometer. The study could provide a reference for understanding the pollution characteristics and pollutants transmission mechanism in Northeast China.