Abstract
This study was conducted for understanding of characteristics of two different high PM episodes occurred during the spring of 2014 in Seoul, Korea. Case 1 was the phenomenon by complex of long range transport and following domestic stagnation. Case 2 was caused by the Asian dust event. During high PM episodes, atmospheric condition became more acidic. The equivalent concentration ratio of nitrate to sulfate decreased to 0.75 and 0.95 in Case 1 and Case 2, respectively, implying that sulfate concentration increase was greater than nitrate concentration increase in high PM episode possibly caused by long range transport. In high PM episodes, SOR and NOR increased with steeper rate for NOR. Considering correlation between temperature and SOR, it was suggested that the homogeneous formation of sulfate was not active in the Korean Peninsula, especially in high PM episodic periods. On the other hand, heterogeneous sulfate formation reaction was dominant for high PM episodes. Considering NOR and its correlation with temperature and humidity, it was suggested that NO2oxidation was mainly caused by homogeneous oxidation in Case 1. For Case 2, heterogeneous oxidation mainly contributed to forming the nitrate due to the extremely high particle concentrations in Asian dust.
Highlights
Atmospheric particulate matter has been considered to play an important role in aggravating climate change and human health [1, 2]
As a result of backward trajectory, the air parcel was moved to the Korean Peninsula through the northeastern part of China, where megacities such as Beijing, Hebei, and Tianjin are located, in the beginning of Case 1 (Figure 3)
Episodes, the chemical components of PM2.5 were monitored and aerosol acidity and oxidation ratios were analyzed in spring 2014
Summary
Atmospheric particulate matter has been considered to play an important role in aggravating climate change and human health [1, 2]. It is important to understand various atmospheric processes of aerosols and find out their emission sources for the establishment of pollution reduction policy to reduce adverse effects of aerosols on climate and public health. Understanding the chemical composition of atmospheric particles is necessary to identify their emission sources and predict their effects on various atmospheric processes [3]. The concentrations of air pollutants in the Korean Peninsula have been influenced by emissions in China and substantial transport of pollutants to the downwind area of China [11]. Understanding the chemical composition of PM especially for high PM episodes in Korea and predicting their emission source through this information are important to estimate the impacts of China, one of the world’s largest emitters
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