Dominant Contributions of Secondary Aerosols and Vehicle Emissions to Water-Soluble Inorganic Ions of PM<sub>2.5</sub> in an Urban Site in the Metropolitan Hangzhou, China
Water soluble inorganic ions (WSIIs) are important components in PM<sub>2.5</sub> and could strongly affect the acidity and hygroscopicity of PM<sub>2.5</sub>. In order to achieve the seasonal characteristics and determine the potential sources of WSIIs in PM<sub>2.5<...
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| Autores principales: | , , , , , , , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/74cfba3893f645d49d5649e4769ff25b |
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| Sumario: | Water soluble inorganic ions (WSIIs) are important components in PM<sub>2.5</sub> and could strongly affect the acidity and hygroscopicity of PM<sub>2.5</sub>. In order to achieve the seasonal characteristics and determine the potential sources of WSIIs in PM<sub>2.5</sub> in Hangzhou, online systems were used to measure hourly mass concentrations of WSIIs (SO<sub>4</sub><sup>2−</sup>, NO<sub>3</sub><sup>−</sup>, NH<sub>4</sub><sup>+</sup>, Cl<sup>−</sup>, Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup> and Mg<sup>2+</sup>) as well as PM<sub>2.5</sub>, NO<sub>2</sub> and SO<sub>2</sub> at an urban site for one month each season (May, August, October, December) in 2017. Results showed that the hourly mass concentrations of PM<sub>2.5</sub> during the whole campaign varied from 1 to 292 μg·m<sup>−3</sup> with the mean of 56.03 μg·m<sup>−3</sup>. The mean mass concentration of WSIIs was 26.49 ± 20.78 μg·m<sup>−3</sup>, which contributed 48.28% to averaged PM<sub>2.5</sub> mass. SNA (SO<sub>4</sub><sup>2−</sup>, NO<sub>3</sub><sup>−</sup> and NH<sub>4</sub><sup>+</sup>) were the most abundant ions in PM<sub>2.5</sub> and on average, they comprised 41.57% of PM<sub>2.5</sub> mass. PM<sub>2.5</sub>, NO<sub>2</sub>, SO<sub>2</sub> and WSIIs showed higher mass concentrations in December, possibly due to higher energy consumption emissions, unfavorable meteorological factors (e.g., lower wind speed and temperature) and regional transport. Results from PCA models showed that secondary aerosols and vehicle emissions were the dominant sources of WSIIs in the observations. Our findings highlight the importance of stronger controls on precursor (e.g., SO<sub>2</sub> and NO<sub>2</sub>) emissions in Hangzhou, and show that industrial areas should be controlled at local and regional scales in the future. |
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