Hygroscopic properties and water-soluble volume fraction of atmospheric particles in the diameter range from 50 nm to 3.8 μm during LACE 98
Hygroscopic properties and water-soluble volume fraction of atmospheric particles in the diameter range from 50 nm to 3.8 μm during LACE 98
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LACE 98期间直径50 nm~3.8 μm大气颗粒物的吸湿特性和水溶性体积分数
DOI：
10.1029/2000jd000228
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发表时间：
2002
影响因子：
--
通讯作者：
C. Neusüß
中科院分区：
文献类型：
--
作者：
B. Busch;K. Kandler;L. Schütz;C. Neusüß
[1]在柏林东南80公里的农村地区进行的林登贝格气溶胶特性实验（LACE 98）中，研究了艾特肯、大颗粒和巨颗粒范围内大气气溶胶颗粒的吸湿特性。Aitken颗粒的吸湿行为在四个尺寸类别（50，100，150，250 nm）中用吸湿串联微分迁移率分析仪在60%和90%的相对湿度（RH）下原位测定。在60%相对湿度下的测量值作为其他LACE 98研究人员用于质量闭合和辐射传输计算的参考数据。在大多数情况下，在90%RH下，大气颗粒物可以分为两组（“更多”和“更少”吸湿部分）具有不同的吸湿特性，而这种分类是不可能的测量在60%RH。对于尺寸为50、100、150和250 nm的颗粒，发现“更”吸湿部分的测量平均生长因子分别为1.43、1.49、1.56和1.63。对于所有颗粒尺寸，“较少”吸湿性模式的生长因子约为1.1。使用吸湿模型估计颗粒的水溶性体积分数，假设颗粒由具有不溶性核的硫酸铵组成。对按尺寸分离的撞击器样品进行的化学分析证实了这一假设。对于“更多”吸湿性颗粒，相应的估计的水溶性体积分数为约0.47、0.52、0.59和0.68，而“更少”吸湿性颗粒的估计的水溶性体积分数为0.1的量级。在60%RH条件下，测得的平均生长因子范围为1.15-1.22，估算的水溶性体积分数范围为0.41-0.59。对于大、巨气溶胶粒子，通过直接测量其水溶性体积分数，扩展了气溶胶可溶性体积分数的测定。研究了直径为0.4-3.8 μm的准单分散样品的七种特定粒径。在此尺寸范围内测量的颗粒显示了多达三类水溶性体积分数：在某些情况下，可以识别出一类几乎不溶的颗粒，对应于Aitken范围内吸湿性较低的部分。第二类对应于更吸湿的部分被发现具有约0.5-0.7的水溶性体积分数。除艾特肯范围外，通常还发现第三类颗粒，其可溶性体积分数约为0.85。在0.7 μm以下，第三类几乎完全溶于水的颗粒占绝对优势;在0.7 μm以上，所有类别的颗粒分布均匀。在LACE 98活动期间，在大型和巨型粒度范围内未观察到显著变化。
[1] Hygroscopic properties of atmospheric aerosol particles in the Aitken, large, and giant particle range were studied during the Lindenberg Aerosol Characterization Experiment (LACE 98) in a rural area 80 km southeast of Berlin. The hygroscopic behavior of Aitken particles were determined in situ in four size classes (50, 100, 150, 250 nm) with a Hygroscopic Tandem Differential Mobility Analyzer for relative humidities (RH) of 60% and 90%. Measurements at 60% RH served as reference data used by other LACE 98 investigators for mass closure and radiative transfer calculations. In most cases, at 90% RH, the atmospheric particles could be classified into two groups (“more” and “less” hygroscopic fraction) with different hygroscopic properties, whereas this classification was not possible for the measurements at 60% RH. The measured average growth factors of the “more” hygroscopic fraction were found to be at 1.43, 1.49, 1.56, and 1.63 for particles with a size of 50, 100, 150, and 250 nm, respectively. Growth factors of the “less” hygroscopic mode were about 1.1 for all particle sizes. The water-soluble volume fraction of the particles was estimated using a hygroscopic model, assuming that the particles consist of ammonium sulfate with an insoluble core. Chemical analysis of size-segregated impactor samples confirmed this assumption. The corresponding estimated water-soluble volume fractions for the “more” hygroscopic particles were about 0.47, 0.52, 0.59, and 0.68, whereas the estimated water-soluble volume fractions of the “less” hygroscopic particles were in the order of 0.1. At 60% RH, the measured average growth factors were in the range of 1.15–1.22, the estimated water-soluble volume fractions were in the range of 0.41–0.59. For large and giant aerosol particles, the determination of the soluble volume fraction was extended by direct measurements with the water-soluble fraction of large and giant aerosol particles system. Quasi-monodisperse samples of particles 0.4–3.8 μm in diameter were investigated for seven specific particle sizes. The particles measured within this size range show up to three classes of water-soluble volume fractions: In some cases, a class of nearly insoluble particles corresponding to the less hygroscopic fraction in the Aitken range can be identified. A second class corresponding to the more hygroscopic fraction is found with a water-soluble volume fraction of about 0.5–0.7. In addition to the Aitken range, a third class of particles with a soluble volume fraction of about 0.85 is usually found. Below 0.7 μm particle size, the third class of nearly complete water-soluble particles is strongly dominant; above 0.7 μm, there is an equal distribution of all classes. No significant variation can be seen during the LACE 98 campaign in the large and giant particle size range.