| Autor: |
Mi-Jung Lee, Hyo-Jin Eom, Shila Maskey, Chul-Un Ro, Kang-Ho Ahn, HyeKyeong Kim, Hae-Jin Jung |
| Rok vydání: |
2012 |
| Předmět: |
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| Zdroj: |
Atmospheric Environment. 60:68-75 |
| ISSN: |
1352-2310 |
| DOI: |
10.1016/j.atmosenv.2012.06.011 |
| Popis: |
Previous controversial studies on the hygroscopic behavior of NaNO 3 aerosol particles and our frequent observation of crystalline NaNO 3 -containing ambient particles prompted this hygroscopic study on NaNO 3 particles. In this work, the hygroscopic behavior of individual NaNO 3 particles of 2.5–4.0 μm in diameter is investigated on a single-particle basis using an optical microscopic technique. Quite different hygroscopic behavior between particles wet dispersed by the nebulization of aqueous NaNO 3 solutions and dry deposited powdery particles was observed; i.e. , most of wet dispersed particles continuously grew and shrank during humidifying and dehydration processes, respectively, and yet all the dry deposited particles had reproducible deliquescence and efflorescence relative humidities (DRHs and ERHs). The different behavior of the two NaNO 3 systems is due to the different nucleation mechanisms. Our hygroscopic study of wet deposited NaNO 3 particles indicates that they nucleate via homogeneous nucleation, but the time scale for the nucleation to occur is too long to be atmospherically relevant. And thus no efflorescence of the particles has been observed in the laboratory measurements. However, when chemical species acting as heterogeneous nuclei are present, then efflorescence occurs which can explain the observation of ambient crystalline NaNO 3 particles. It is imperative to work with heterogeneous nucleation systems which are more relevant to the real world. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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Full Text from ScienceDirect