New particle formation (NPF) is considered as an important mechanism for gas-to-particle transformation, and gaseous sulfuric acid is believed as a crucial precursor. Up to now few field-based studies on nucleation mechanisms and the role of sulfuric acid were conducted in China. In this study, simultaneously measurements of particle number size distributions and gaseous sulfuric acid concentrations were performed from July to September in 2008. Totally, 22 new particle formation events were observed during the entire 85 campaign days. The results show that in the case of both higher source and sink values, the result of the competition between source and sink is more likely the key limiting factor to determine the observation of NPF events in Beijing. The concentrations of gaseous sulfuric acid show good correlations with freshly nucleated particles (N3-6 and formation rates (J3 and J1.5. The power-law relationship between H2SO4 concentration and N3-6 or J is adopted to explore the nucleation mechanism. The exponents are showed a great range (from 1 to 7). More than half of the NPF events exhibit an exponent larger than 2.5. For these cases, the thermodynamic process works better than the activation or kinetic nucleation theories to explain the nucleation events in urban atmosphere of Beijing.
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机译：新的颗粒形成（NPF）被认为是气 - 颗粒转化的重要机制，并且认为气态硫酸作为关键前体。截至目前，少量基于核心机制的基于核心的研究和硫酸的作用在中国进行。在该研究中，同时测量粒子数尺寸分布和气态硫酸浓度，于2008年7月至9月进行。完全，在整个85个竞选日内观察到22个新的颗粒形成事件。结果表明，在较高的来源和下沉值的情况下，源和水槽之间的竞争结果更有可能是确定北京NPF事件观察的关键限制因素。气态硫酸的浓度显示出与新鲜核颗粒的良好相关性（N3-6和形成速率（J3和J1.5。采用H 2 SO 4浓度和N3-6或J之间的动力 - 法关系来探索成核机制。该指数显示出很大的范围（从1到7）。超过一半的NPF事件表现出大于2.5的指数。对于这些情况，热力学过程优于激活或动力学成核理论，以解释城市中的成核事件北京气氛。
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