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摘要
Secondary new particle formation (NPF) plays a significant role in atmospheric particulate matters (e.g., PM2.5), and has been studied over the past decades. However, the mechanism of NPF still remains ambiguous, setting significant barrier for PM2.5 mitigations, especially in complex atmosphere with multi-pollutants. Since the NPF process can hardly be observed directly by experiment methods due to the measuring limitations, a multicomponent kinetic model (MKM), which can be used to analyze the process and the mechanism of NPF in H2SO4-HNO3-NH3-VOC (Volatile Organic Compounds) system, has been developed in this paper. According to MKM, seven cases with initial concentrations of total precursor vapors (CPV) in the range of 10(7)-10(8) cm(-3) were calculated to analyze the NPF process. Firstly, the 3 nm particle (PM (3nm)) formation rate was calculated via MKM, which showed a good agreement with the previous measurements. Moreover, according to MKM calculation, it is found that the peak value of PM3nm formation rate, i.e., J(m), is proportional to [CPV](2), while the time at which J(m) occurred, i.e., t(m), is proportional to [CPV](-1/3), indicating that the increases in CPV would lead to a significant increase of Jm and decrease of tm. That's why NPF bursts immediately and PM2.5 pollution occurs suddenly in heavily pollutant areas. Afterwards, the roles of precursors in H2SO4-HNO3-NH3-VOC system were identified. It indicates that H2SO4, NH3 and VOC mainly contribute to the early stage of the NPF, while the growth of the nuclei is mainly driven by HNO3 and NH3. And HNO3 makes increasing contributions at the early stage of NPF with CPV rising (especially above 108 cm(-3)). Thus in high CPV areas, especially for China, HNO3 should be paid the same attention as H2SO4, NH3 and VOC. The findings provide important implications for haze mitigations in China and other industrializing countries with multi-pollutant emission sources.
- 出版日期2018-3
- 单位北京科技大学
