Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area
The aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, <i>d</i> ≤ 100 nm) and submicron particles (PM<sub>1</sub>, <i>d</i> ≤ 1 µm) in an east Asian urban area, which are hypot...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2016-02-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/16/1317/2016/acp-16-1317-2016.pdf |
| _version_ | 1818366916817846272 |
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| author | H. C. Cheung C. C.-K. Chou M.-J. Chen W.-R. Huang S.-H. Huang C.-Y. Tsai C. S. L. Lee |
| author_facet | H. C. Cheung C. C.-K. Chou M.-J. Chen W.-R. Huang S.-H. Huang C.-Y. Tsai C. S. L. Lee |
| author_sort | H. C. Cheung |
| collection | DOAJ |
| description | The aim of this study is to investigate the seasonal variations in the
physicochemical properties of atmospheric ultra-fine particles (UFPs, <i>d</i> ≤ 100 nm) and submicron particles (PM<sub>1</sub>, <i>d</i> ≤ 1 µm) in an
east Asian urban area, which are hypothesized to be affected by the
interchange of summer and winter monsoons. An observation experiment was
conducted at TARO (Taipei Aerosol and Radiation Observatory), an urban
aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The
measurements included the mass concentration and chemical composition of
UFPs and PM<sub>1</sub>, as well as the particle number concentration (PNC) and the
particle number size distribution (PSD) with size range of 4–736 nm. The results
indicated that the mass concentration of PM<sub>1</sub> was elevated during cold
seasons with a peak level of 18.5 µg m<sup>−3</sup> in spring, whereas the
highest concentration of UFPs was measured in summertime with a mean of 1.64 µg m<sup>−3</sup>.
Moreover, chemical analysis revealed that the UFPs and
PM<sub>1</sub> were characterized by distinct composition; UFPs were composed
mostly of organics, whereas ammonium and sulfate were the major constituents
of PM<sub>1</sub>. The seasonal median of total PNCs ranged from 13.9 × 10<sup>3</sup> cm<sup>−3</sup> in autumn to 19.4 × 10<sup>3</sup> cm<sup>−3</sup> in spring.
Median concentrations for respective size distribution modes peaked in
different seasons. The nucleation-mode PNC (<i>N</i><sub>4 − 25</sub>) peaked at
11.6 × 10<sup>3</sup> cm<sup>−3</sup> in winter, whereas the Aitken-mode
(<i>N</i><sub>25 − 100</sub>) and accumulation-mode (<i>N</i><sub>100 − 736</sub>) PNC exhibited summer maxima
at 6.0 × 10<sup>3</sup> and 3.1 × 10<sup>3</sup> cm<sup>−3</sup>,
respectively. The change in PSD during summertime was attributed to the
enhancement in the photochemical production of condensable organic matter
that, in turn, contributed to the growth of aerosol particles in the
atmosphere. In addition, clear photochemical production of particles was
observed, mostly in the summer season, which was characterized by average
particle growth and formation rates of 4.0 ± 1.1 nm h<sup>−1</sup> and
1.4 ± 0.8 cm<sup>−3</sup> s<sup>−1</sup>, respectively. The prevalence of new
particle formation (NPF) in summer was suggested as a result of seasonally
enhanced photochemical oxidation of SO<sub>2</sub> that contributed to the
production of H<sub>2</sub>SO<sub>4</sub>, and a low level of PM<sub>10</sub> (<i>d</i> ≤ 10 µm) that served as the condensation sink. Regarding the sources of aerosol
particles, correlation analysis of the PNCs against NO<sub><i>x</i></sub> revealed that
the local vehicular exhaust was the dominant contributor of the UFPs
throughout the year. Conversely, the Asian pollution outbreaks had
significant influence in the PNC of accumulation-mode particles during the
seasons of winter monsoons. The results of this study implied the
significance of secondary organic aerosols in the seasonal variations of
UFPs and the influences of continental pollution outbreaks in the downwind
areas of Asian outflows. |
| first_indexed | 2024-12-13T22:43:46Z |
| format | Article |
| id | doaj.art-050ad2fbffad4bc5a7078113558422bd |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-13T22:43:46Z |
| publishDate | 2016-02-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-050ad2fbffad4bc5a7078113558422bd2022-12-21T23:28:47ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242016-02-01161317133010.5194/acp-16-1317-2016Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban areaH. C. Cheung0C. C.-K. Chou1M.-J. Chen2W.-R. Huang3S.-H. Huang4C.-Y. Tsai5C. S. L. Lee6Research Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanResearch Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanResearch Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanResearch Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanResearch Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanResearch Center for Environmental Changes, Academia Sinica, Taipei 11529, TaiwanInstitute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, TaiwanThe aim of this study is to investigate the seasonal variations in the physicochemical properties of atmospheric ultra-fine particles (UFPs, <i>d</i> ≤ 100 nm) and submicron particles (PM<sub>1</sub>, <i>d</i> ≤ 1 µm) in an east Asian urban area, which are hypothesized to be affected by the interchange of summer and winter monsoons. An observation experiment was conducted at TARO (Taipei Aerosol and Radiation Observatory), an urban aerosol station in Taipei, Taiwan, from October 2012 to August 2013. The measurements included the mass concentration and chemical composition of UFPs and PM<sub>1</sub>, as well as the particle number concentration (PNC) and the particle number size distribution (PSD) with size range of 4–736 nm. The results indicated that the mass concentration of PM<sub>1</sub> was elevated during cold seasons with a peak level of 18.5 µg m<sup>−3</sup> in spring, whereas the highest concentration of UFPs was measured in summertime with a mean of 1.64 µg m<sup>−3</sup>. Moreover, chemical analysis revealed that the UFPs and PM<sub>1</sub> were characterized by distinct composition; UFPs were composed mostly of organics, whereas ammonium and sulfate were the major constituents of PM<sub>1</sub>. The seasonal median of total PNCs ranged from 13.9 × 10<sup>3</sup> cm<sup>−3</sup> in autumn to 19.4 × 10<sup>3</sup> cm<sup>−3</sup> in spring. Median concentrations for respective size distribution modes peaked in different seasons. The nucleation-mode PNC (<i>N</i><sub>4 − 25</sub>) peaked at 11.6 × 10<sup>3</sup> cm<sup>−3</sup> in winter, whereas the Aitken-mode (<i>N</i><sub>25 − 100</sub>) and accumulation-mode (<i>N</i><sub>100 − 736</sub>) PNC exhibited summer maxima at 6.0 × 10<sup>3</sup> and 3.1 × 10<sup>3</sup> cm<sup>−3</sup>, respectively. The change in PSD during summertime was attributed to the enhancement in the photochemical production of condensable organic matter that, in turn, contributed to the growth of aerosol particles in the atmosphere. In addition, clear photochemical production of particles was observed, mostly in the summer season, which was characterized by average particle growth and formation rates of 4.0 ± 1.1 nm h<sup>−1</sup> and 1.4 ± 0.8 cm<sup>−3</sup> s<sup>−1</sup>, respectively. The prevalence of new particle formation (NPF) in summer was suggested as a result of seasonally enhanced photochemical oxidation of SO<sub>2</sub> that contributed to the production of H<sub>2</sub>SO<sub>4</sub>, and a low level of PM<sub>10</sub> (<i>d</i> ≤ 10 µm) that served as the condensation sink. Regarding the sources of aerosol particles, correlation analysis of the PNCs against NO<sub><i>x</i></sub> revealed that the local vehicular exhaust was the dominant contributor of the UFPs throughout the year. Conversely, the Asian pollution outbreaks had significant influence in the PNC of accumulation-mode particles during the seasons of winter monsoons. The results of this study implied the significance of secondary organic aerosols in the seasonal variations of UFPs and the influences of continental pollution outbreaks in the downwind areas of Asian outflows.https://www.atmos-chem-phys.net/16/1317/2016/acp-16-1317-2016.pdf |
| spellingShingle | H. C. Cheung C. C.-K. Chou M.-J. Chen W.-R. Huang S.-H. Huang C.-Y. Tsai C. S. L. Lee Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area Atmospheric Chemistry and Physics |
| title | Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area |
| title_full | Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area |
| title_fullStr | Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area |
| title_full_unstemmed | Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area |
| title_short | Seasonal variations of ultra-fine and submicron aerosols in Taipei, Taiwan: implications for particle formation processes in a subtropical urban area |
| title_sort | seasonal variations of ultra fine and submicron aerosols in taipei taiwan implications for particle formation processes in a subtropical urban area |
| url | https://www.atmos-chem-phys.net/16/1317/2016/acp-16-1317-2016.pdf |
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