- Our Research
Long-term trends in the East-Asian continental pollution outbreaks and background air quality around Taiwan The East-Asia (EA), in particular the eastern and northern China, is one of the major source regions of air pollutants in the world. The pollutants transported with the EA continental outflows could have significant impacts to the atmospheric composition and air quality in the downwind areas. Taiwan is under the lee side of the winter monsoons originating in the EA continent and, consequently, receives air pollutants transported by the monsoons. Long-term observation of the atmospheric composition at background sites deserves our efforts because it could provide crucial evidences for the changes in our environment.
Production, transformation and transport of ozone and aerosols with implications for air pollution control strategies Fine particulate matter (PM2.5) and ozone (O3) are the major air pollutants in not only Taiwan but also most of the urban areas in the world. Formulation of an effective control strategy for the ambient levels of PM2.5 and O3 is thereby a great challenge. Both O3 and a large fraction of PM2.5 are known as secondary pollutants, which are products of atmospheric chemical reactions among the gaseous precursors emitted from respective pollution sources. An in-depth study upon the physical and chemical processes will improve our scientific knowledge for the formulation of strategies of pollution reduction.
Adcock, K. E., Ashfold, M. J., Chou, C. C.-K., Gooch, L. J., Mohd Hanif, N., Laube, J. C., Oram, D. E., Ou-Yang, C.-F., Panagi, M., Sturges, W. T., Reeves, C. (2020). Investigation of East Asian emissions of CFC-11 using atmospheric observations in Taiwan. Environmental Science & Technology, 54, 3814-3822.
Cheung, H. C., Chou, C. C.-K., Lee, C. S. L., Kuo, W.-C., and Chang, S.-C. (2020). Hygroscopic properties and cloud condensation nuclei activity of atmospheric aerosols under the influences of Asian continental outflow and new particle formation at a coastal site in eastern Asia. Atmos. Chem. Phys., 20, 5911–5922.
Jung, C.-C., Chou, C. C.-K., Lin, C.-Y., Shen, C.-C., Lin, Y.-C., Huang, Y.-T., Tsai, C.-Y., Yao, P.-H., Huang, C.-R., Huang, W.-R., Chen, M.-J., Huang, S.-H., Chang, S.-C. (2019). C-Sr-Pb isotopic characteristics of PM2.5 transported on the East-Asian continental outflows. Atmospheric Research, 223, 88-97.
Lee, C. S. L., Chou, C. C.-K., Cheung, H. C., Tsai, C.-Y., Huang, W.-R., Huang, S.-H., Chen, M.-J., Liao, H.-T., Wu, C.-F., Tsao, T.-M., Tsai, M.-J., Su, T.-C. (2019). Seasonal variation of chemical characteristics of fine particulate matter at a high-elevation subtropical forest in East Asia. Environmental Pollution, 246, 668-677.
Chou, C. C.-K., Hsu, W.-C., Chang, S.-Y., Chen, W.-N., Chen, M.-J., Huang, W.-R., Huang, S.-H., Tsai, C.-Y., Chang, S.-C., Lee, C.-T., Liu, S.-C. (2017). Seasonality of the mass concentration and chemical composition of aerosols around an urbanized basin in East Asia. J. Geophys. Res. Atmos., 122, doi:10.1002/ 2016JD025728.
Salvador, C. M., Ho, T.-T., Chou, C. C.-K., Chen, M.-J., Huang, W.-R., Huang, S.-H. (2016). Characterization of the organic matter in submicron urban aerosols using a Thermo-Desorption Proton-Transfer-Reaction Time-of-Flight Mass Spectrometer (TD-PTR-TOF-MS). Atmospheric Environment, 140, 565-575.
Cheung, H. C., Chou, C. C.-K., Chen, M.-J., Huang, W.-R., Huang, S.-H., Tsai, C.-Y., Lee, C. S. L. (2016). Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area. Atmos. Chem. Phys., 16, 1317-1330.
Cheung, H. C., Chou, C. C.-K., Huang, W.-R., and Tsai, C.-Y. (2013). Characterization of ultrafine particle number concentration and new particle formation in urban environment of Taipei, Taiwan. Atmos. Chem. Phys., 13, 8935-8946.
Chou, C. C.-K., Tsai, C.-Y., Chang, C.-C., Lin, P.-H., Liu, S. C., Zhu, T. (2011). Photochemical production of ozone in Beijing during the 2008 Olympic Games. Atmos. Chem. Phys., 11, 9825-9837.
Chou, C. C.-K., Lee, C. T., Cheng, M. T., Yuan, C. S., Chen, S. J., Wu, Y. L., Hsu, W. C., Lung, S. C., Hsu, S. C., Lin, C. Y., Liu, S. C. (2010). Seasonal variations and spatial distribution of carbonaceous aerosols in Taiwan. Atmos. Chem. Phys, 10, 9563–9578.
Hygroscopic properties and cloud condensation nuclei activity of atmospheric aerosols under the influences of Asian continental outflow and new particle formation at a coastal site in eastern Asia . (Cheung et al., Atmos. Chem. Phys., 20, 5911–5922, 2020) This paper presents observations on hygroscopicity and chemical composition of aerosols at the Cape Fuguei Research Station (CAFÉ). Here we show that the aerosols transported from China by the Asian outflows are more hydrophilic than local air pollutants, which implies stronger regional climate impacts caused by the Asian outflow aerosols. In addition, we revealed the influences of new particle formation in the budget and physicochemical properties of aerosols at the northern coastal area of Taiwan, indicating the impacts of gas-to-particle processes.
Seasonal variation of chemical characteristics of fine particulate matter at a high-elevation subtropical forest in East Asia. (Lee et al., Environmental Pollution, 246, 668-677, 2019) This study investigated the connection between the transport of urban air pollutants and the variations in the physico-chemical characteristics of PM2.5 in the Xitou Experimental Forest, which located downwind the Taichung Metropolis. We found that the atmosphere in Xitou was characterized with significantly higher oxidation state in sulfur and nitrogen species than in the general cases in urban areas. The results suggested that the gaseous air pollutants (i.e. SO2 and NOx) were efficiently converted to particulate sulfate and nitrate during the transport. It was inferred that enhanced aqueous-phase and/or heterogeneous reactions could have contributed to the formation of sulfate and nitrate in Xitou. This study demonstrated the significant footprint of urban air pollutants in a subtropical forest due to the mountain-valley circulations, whereas the implications of which for regional climate change and the function of forest ecosystem necessitated further investigation.
Seasonality of the mass concentration and chemical composition of aerosols around an urbanized basin in East Asia. (Chou et al., J. Geophys. Res. Atmos., 122, 2026 – 2042, 2017) This investigation produced a 3-year (2009 - 2011) dataset of daily based aerosol composition in this area, which is so far the only one in Taiwan and very rare even worldwide. This data is crucial to further studies upon the changes in urban air quality and atmospheric composition in this region. In this paper we underlined the significance of heterogeneous reactions between nitric acid and sea salt or dust particles, which might have caused sea salt and dust particle transformation and thereby altered microphysical behavior of aerosols.