Identification and quantification of particle growth channels during new particle formation
Identification and quantification of particle growth channels during new particle formation
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DOI：
10.5194/acp-13-10215-2013
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发表时间：
2013-04
影响因子：
6.3
通讯作者：
M. Pennington;B. Bzdek;J. DePalma;J. Smith;A. Kortelainen;L. H. Ruiz;T. Petäjä;M. Kulmala;
中科院分区：
文献类型：
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作者：
M. Pennington;B. Bzdek;J. DePalma;J. Smith;A. Kortelainen;L. H. Ruiz;T. Petäjä;M. Kulmala;
抽象的。大气新粒子形成（NPF）是大气超细粒子的一个重要来源，对全球云凝结核（CCN）的产生有重要贡献。虽然NPF由大气成核驱动，但其对CCN浓度的影响强烈取决于大气生长机制，因为生长速率必须超过由于清除而导致的损失速率，以使颗粒达到CCN尺寸范围。在这项工作中，2011年3月至4月在芬兰Hyytiala进行的NPF期间，对直径为20 nm的颗粒进行了化学成分测量，以识别和定量评估重要的生长通道。在这项工作中，我们表明：（A）硫酸，一个与大气成核相关的关键物质，在这段时间内占颗粒质量增长的不到一半;（B）NPF期间生长颗粒的硫酸盐含量通过气相硫酸分子的冷凝定量解释（即，硫酸吸收是碰撞限制的）;（C）在新的颗粒已经生长到足以被测量的尺寸之前，硫酸冷凝实质上影响预先存在的纳米颗粒的化学组成;（D）铵和硫酸盐浓度高度相关，表明氨吸收由硫酸吸收驱动;（E）铵对硫酸盐的中和作用没有达到预测的热力学终点，这表明氨吸收存在障碍;（F）碳质物质占颗粒质量增长的一半以上，其氧碳比（~ 0.5）是新形成的二次有机气溶胶的特征;和（G）从一个形成事件到另一个形成事件的总生长速率的差异是由所有主要化学物质的生长速率的变化引起的，而不仅仅是一个单独的物质。
Abstract. Atmospheric new particle formation (NPF) is a key source of ambient ultrafine particles that may contribute substantially to the global production of cloud condensation nuclei (CCN). While NPF is driven by atmospheric nucleation, its impact on CCN concentration depends strongly on atmospheric growth mechanisms since the growth rate must exceed the loss rate due to scavenging in order for the particles to reach the CCN size range. In this work, chemical composition measurements of 20 nm diameter particles during NPF in Hyytiala, Finland, in March–April 2011 permit identification and quantitative assessment of important growth channels. In this work we show the following: (A) sulfuric acid, a key species associated with atmospheric nucleation, accounts for less than half of particle mass growth during this time period; (B) the sulfate content of a growing particle during NPF is quantitatively explained by condensation of gas-phase sulfuric acid molecules (i.e., sulfuric acid uptake is collision-limited); (C) sulfuric acid condensation substantially impacts the chemical composition of preexisting nanoparticles before new particles have grown to a size sufficient to be measured; (D) ammonium and sulfate concentrations are highly correlated, indicating that ammonia uptake is driven by sulfuric acid uptake; (E) sulfate neutralization by ammonium does not reach the predicted thermodynamic end point, suggesting that a barrier exists for ammonia uptake; (F) carbonaceous matter accounts for more than half of the particle mass growth, and its oxygen-to-carbon ratio (~ 0.5) is characteristic of freshly formed secondary organic aerosol; and (G) differences in the overall growth rate from one formation event to another are caused by variations in the growth rates of all major chemical species, not just one individual species.