Evaluation of the performance of a particle concentrator for online instrumentation
Evaluation of the performance of a particle concentrator for online instrumentation
复制标题
在线仪器颗粒集中器的性能评估
DOI：
10.5194/amt-7-2121-2014
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发表时间：
2014
影响因子：
3.8
通讯作者：
J. Jimenez
中科院分区：
文献类型：
--
作者：
S. Saarikoski;S. Carbone;M. Cubison;R. Hillamo;P. Keronen;C. Sioutas;D. Worsnop;J. Jimenez
抽象的。微型多功能气溶胶浓度富集系统（m-VACES; Geller等人，2005）在实验室和现场研究中使用在线仪器进行了调查。采用空气动力学粒度仪（APS）和扫描迁移率粒度仪（SMPS）对单分散硫酸铵（AS）和癸二酸二辛酯（DOS）颗粒在m-VACES中的行为进行了研究。在芬兰赫尔辛基的一个城市场地进行了环境测量，在那里，除了SMPS外，还结合烟尘粒子气溶胶质谱仪（SP-AMS）探索了m-VACES的操作。在实验室测试中，水蒸气中颗粒的生长产生了与原始颗粒尺寸无关的稳定的液滴尺寸分布。然而，当以测量原始尺寸分布为目的干燥液滴时，对于小颗粒尺寸（移动直径高达~ 200 nm）观察到向较大颗粒的转变。这种增长可能是由于水溶性有机化合物从气相中吸附在水滴上，但在干燥阶段没有蒸发。在环境测量中，观察到类似的富集硝酸盐和硫酸盐的m-VACES，而酸性环境颗粒的存在下，影响富集铵。气态氨很可能被吸收在m-VACES中的酸性颗粒上，中和气溶胶。对于有机物，富集效率与硫酸盐和硝酸盐相当，但注意到烃和含氮有机化合物的小阳性伪影。用正矩阵分解法（PMF）对大气和浓有机气溶胶（OA）进行了分析。为两个数据集选择了三因素解决方案，但环境和浓缩OA的因素略有不同，然而，用于PMF分析的数据集大小有限（3天），因此具有很大的不确定性。总体而言，未发现m-VACES的操作导致任何严重的采样伪影。在气溶胶呈酸性的地方，酸度的影响可能是一个问题，但是，在这些情况下，建议使用扩散管（本研究中没有使用）。由于本研究中环境测量的时间仅为5天，因此需要进一步的环境测试来表征m-VACES。特别是对于OA，额外的测试非常重要，因为有机物的化学性质可能因时间和地点而有很大差异。
Abstract. The performance of the miniature Versatile Aerosol Concentration Enrichment System (m-VACES; Geller et al., 2005) was investigated in laboratory and field studies using online instruments. Laboratory tests focused on the behavior of monodisperse ammonium sulfate (AS) or dioctyl sebacate (DOS) particles in the m-VACES measured with the aerodynamic particle sizer (APS) and scanning mobility particle sizer (SMPS). The ambient measurements were conducted at an urban site in Helsinki, Finland, where the operation of the m-VACES was explored in conjunction with a Soot Particle Aerosol Mass Spectrometer (SP-AMS) in addition to the SMPS. In laboratory tests, the growth of particles in water vapor produced a stable droplet size distribution independent of the original particle size. However, when the droplets were dried with the goal of measuring the original size distribution, a shift to larger particles was observed for small particle sizes (up to ~ 200 nm in mobility diameter). That growth was probably caused by water-soluble organic compounds absorbed on the water droplets from the gas phase, but not evaporated in the drying phase. In ambient measurements, a similar enrichment was observed for nitrate and sulfate in the m-VACES whereas the presence of acidic ambient particles affected the enrichment of ammonium. Gaseous ammonia was likely to be absorbed on acidic particles in the m-VACES, neutralizing the aerosol. For organics, the enrichment efficiency was comparable with sulfate and nitrate but a small positive artifact for hydrocarbons and nitrogen-containing organic compounds was noticed. Ambient and concentrated organic aerosol (OA) was analyzed further with positive matrix factorization (PMF). A three-factor solution was chosen for both of the data sets but the factors were slightly different for the ambient and concentrated OA, however, the data set used for the PMF analysis was limited in size (3 days) and therefore had substantial uncertainty. Overall, the operation of the m-VACES was not found to lead to any severe sampling artifacts. The effect of acidity could be an issue in locations where the aerosol is acidic, however, in those cases the use of a denuder (which was not used in this study) is recommended. Further ambient tests are needed for the characterization of the m-VACES as the time period for the ambient measurements was only 5 days in this study. Especially for OA additional tests are important as the chemical properties of organics can differ widely depending on time and location.
影响因子：
158.5
作者：
DOCKERY, DW;POPE, CA;SPEIZER, FE
通讯作者：
SPEIZER, FE