Sub‐3 nm particles observed at the coastal and continental sites in the United States
Sub‐3 nm particles observed at the coastal and continental sites in the United States
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DOI：
10.1002/2013jd020841
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
Huan Yu;A. Gannet Hallar;Y. You;A. Sedlacek;S. Springston;V. Kanawade;Yin‐Nan Lee;Jian Wang
中科院分区：
文献类型：
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作者：
Huan Yu;A. Gannet Hallar;Y. You;A. Sedlacek;S. Springston;V. Kanawade;Yin‐Nan Lee;Jian Wang
直接测量大气中的亚3 nm颗粒对于理解新的颗粒形成机制至关重要，但目前这种测量非常有限。我们报告了在布鲁克海文，纽约（夏季的沿海站点）和俄亥俄州的肯特（冬季的大陆站点）测量的亚3纳米颗粒。在白天，在两个研究中心约80%的观察日，观察到浓度为2800 ± 1600 cm-3的亚3 nm颗粒事件，并且它们随着硫酸浓度升高而出现。在夜间，受海洋气团影响的沿海地区也有大量的3纳米以下颗粒（1500 ± 400 cm-3），但它们没有变大。另一方面，在大陆气团影响下的布鲁克海文沿海站点和夜间内陆肯特站点，亚3纳米颗粒明显较低（190 ± 130 cm-3）。我们的研究结果表明，亚3纳米颗粒并不总是存在，它们的存在与特定的气溶胶成核前体密切相关：硫酸和其他可能存在于海洋气团中的未知可冷凝化学物质。因此，这些发现与在芬兰北方森林中进行的其他研究不同，这些研究表明持续存在高浓度的2nm以下颗粒，并且这些2nm以下颗粒与单萜氧化产物的相关性大于硫酸。因此，不同的成核机制，而不是一个通用的机制，涉及不同的成核前体占主导地位，在不同的大气环境中，不同的排放和运输的微量气体。
Direct measurements of atmospheric sub‐3 nm particles are crucial for understanding the new particle formation mechanisms, but such measurements are very limited at present. We report measurements of sub‐3nm particles at Brookhaven, New York (a coastal site in summer) and Kent, Ohio (a continental site in winter). During daytime, in approximately 80% of the observation days at both sites, sub‐3nm particle events were observed with concentrations of 2800 ± 1600 cm‐3, and they appeared with the elevated sulfuric acid concentrations. During the nighttime at the coastal site under the marine air mass influences, there were also substantial concentrations of sub‐3nm particles (1500 ± 400 cm‐3), but they did not grow larger. On the other hand, at the coastal Brookhaven site under the continental air mass influences and at the inland Kent site during the night, the sub‐3nm particles were significantly lower (190 ± 130 cm‐3). Our results indicate that sub‐3nm particles were not always present, and their presence was rather closely associated with specific aerosol nucleation precursors: sulfuric acid and other unknown condensable chemical species likely present in the marine air masses. These findings are thus different from other studies conducted in the Finland boreal forest, which showed a persistent presence of high concentrations of sub‐2nm particles and that these sub‐2nm particles were more correlated to monoterpene oxidation products than to sulfuric acid. Therefore, different nucleation mechanisms, as opposed on to a universal mechanism, involving different nucleation precursors dominate in different atmospheric environments with different emissions and transported trace gases.