| Autor: |
Zhao, Minjiang, Wang, Shuxiao, Tan, Jihua, Hua, Yang, Wu, Di, Hao, Jiming |
| Zdroj: |
Aerosol and Air Quality Research; June 2016, Vol. 16 Issue: 6 p1378-1389, 12p |
| Abstrakt: |
To understand the air pollution problem in megacities such as Beijing, field measurement investigating the variation of NH3and its association with PM2.5chemical property was conducted from 25 November to 24 December 2013. The results indicated that the daily concentration of wintertime NH3tended to be high on the days with relatively high temperatures and low wind speeds. Affected by the synoptic condition, NH3concentration showed a bimodal diurnal variation pattern, which tended to peak at around 09:00 and 22:00 of the day. As the sole precursor for NH4+, NH3exerted a significant impact on the ion chemistry of PM2.5through enhancing the nighttime NH4Cl formation and promoting both homogeneous and heterogeneous formation of NO3−. During heavy pollution episodes with PM2.5concentrations over 200 µg m−3, the NH3levels and NH4+/NH3ratios grew simultaneously with the increase of PM2.5levels, indicating that NH3is one of the key reasons for heavy pollution events. Revealed by the features of measured ionic species in PM2.5, in conjunction with the acidity analysis using thermodynamic model, our results suggested that NH3was frequently sufficient in wintertime atmosphere of urban Beijing and the fine particulates were neutralized nearly fully by NH3. |
| Databáze: |
Supplemental Index |
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