Abstract

Asian dust storms (ADS), coming from deserts of China and Mongolia, have serious environmental impact on particulate matter (PM) and other pollutants in Taiwan. This study selected two urban sites, Taipei and Kaohsiung, to evaluate the influence of ADS on air quality. During the ADS periods, the hourly PM10 mass concentrations were 800 µg m–3 in Taipei and the 400 µg m–3 in Kaohsiung, which was three to five times higher than PM episodes during the non-ADS periods. By using the principal component analysis (PCA) manner, the potential sources, the dust storm contained, can be successfully identified during ADS periods. The other potential sources can be identified as vehicular emission and secondary organic aerosols from local area. There have been many studies conducted on the impact of ADS on airborne coarse particle concentration, but very few on fine particle concentration. This study focused on, using PCA for analysis and discussion, the impact of ADS on submicron particle size distribution. The results showed that there was no close relationship between the ADS and Aitken mode (30–100 nm or D30–100nm) or accumulation mode (from 0.1–1 µm). However, it was found that strong correlation existed between the ADS and nucleation mode (10–30 nm or D10–30nm). In addition, it was found that nucleation mode appeared first, followed by an air plume of dust particles twelve (12) hours later. The nucleation component from the PCA could be used as predictors of arrival time for an ADS. Taking into account the effects of meteorological conditions and employing technique of backward trajectories, PCA can be utilized as a powerful tool to better identify the source of dust storms and provide accurate results.

Highlights

  • Asian dust storms (ADS), which come from the deserts of China and Mongolia (Natsagdorj et al, 2003; Aoki et al, 2005), increase the airborne coarse particle concentration and bring anthropogenic pollutants into China, Japan, Korea, Taiwan and sometimes northern Pacific Ocean areas. (Guo et al, 2004; Ma et al, 2005; Liu et al, 2006; Han et al, 2008; Hwang et al, 2008)

  • The results revealed that the mass concentration in ADS was roughly three to five times higher than that of the highest concentration measured in Taiwan during the nonADS seasons

  • Combining PM2.5 chemical composition and size distribution from 14 to 500 nm data sets have produced a better identification of potential pollutant sources during ADS periods and non-ADS periods

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Summary

Introduction

Asian dust storms (ADS), which come from the deserts of China and Mongolia (Natsagdorj et al, 2003; Aoki et al, 2005), increase the airborne coarse (size distribution > 2.5 μm) particle concentration and bring anthropogenic pollutants into China, Japan, Korea, Taiwan and sometimes northern Pacific Ocean areas. (Guo et al, 2004; Ma et al, 2005; Liu et al, 2006; Han et al, 2008; Hwang et al, 2008). By using the principal component analysis (PCA) manner, the potential sources, the dust storm contained, can be successfully identified during ADS periods. By combining the HYSPLIT model and PCA manner, this study tries to identify potential sources from local areas or external areas, examine the relationship between the particle size distributions and investigate spatiotemporal features of air pollutants during ADS and non-ADS episodes.

Results
Conclusion

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