Sulfate-coated dust particles in the free troposphere over Japan
Sulfate-coated dust particles in the free troposphere over Japan
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DOI：
10.1016/j.atmosres.2006.02.024
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发表时间：
2006-12
影响因子：
5.5
通讯作者：
T. Kojima;P. Buseck;Y. Iwasaka;A. Matsuki;D. Trochkine
中科院分区：
文献类型：
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作者：
T. Kojima;P. Buseck;Y. Iwasaka;A. Matsuki;D. Trochkine
2001年3月在若崎湾（36°00′n, 135°30′e）和7月在库野远海（34°00′n, 136°50′e）和濑户远海（35°10′n, 137°10′e）高度1.0 ~ 5.8 km进行了空气气溶胶收集。使用透射电子显微镜（TEM）对颗粒进行了单独分析。相对较大的矿物粉尘（主要是粘土）颗粒在3月的样品中丰富。7月在对流层中海拔4 km以上的地区也以海盐和硫酸铵为主，而在海拔较低的地区海盐和硫酸铵较多。涂有钙的栅格样品显示了许多硫酸盐液滴的痕迹。在取样时，随着相对湿度的增加，原硫酸盐液滴占总收集颗粒的比例明显增加。TEM分析显示，这些以前的液滴中有很大一部分包裹着矿物粉尘颗粒、海盐、煤烟和飞灰。有些包裹着矿物粉尘、海盐、煤烟和飞灰颗粒的混合物。结果表明，来自亚洲大陆的矿物粉尘在自由对流层中运输时可以获得硫酸盐涂层。矿物粉尘颗粒可能通过气态so2的非均相吸收和随后的氧化或与云或雾滴的凝聚而获得硫酸盐涂层。硫酸盐液滴中混合颗粒的存在也表明不同来源的颗粒通过云处理发生了聚集。这种被硫酸盐包裹的尘埃颗粒会影响云的形成、降水和自由对流层的化学性质。
Airborne aerosol collections were performed over Wakasa bay (36°00′N, 135°30′E) in March and Kumano open sea (34°00′N, 136°50′E) and Seto (35°10′N, 137°10′E) in July 2001 at altitudes between 1.0 and 5.8 km. The particles were individually analyzed using transmission electron microscopy (TEM). Relatively large mineral-dust (mostly clay) particles were abundant in the March samples. They also dominated in July in the mid-troposphere higher than 4 km altitude, whereas sea salt and ammonium sulfate were more abundant at lower altitudes. Ca-coated grid samples show many traces of aqueous sulfate droplets. The proportions of former sulfate droplets to the total collected particles apparently increased with increasing relative humidity at the time of sampling. TEM analysis revealed that a significant fraction of these former droplets enclose mineral-dust particles as well as sea salt, soot, and fly ash. Some enclose mixtures of mineral-dust, sea-salt, soot, and fly ash particles. The results provide evidence that mineral dust from the Asian continent could acquire coatings of sulfate while being transported in the free troposphere. The mineral-dust particles probably acquired the sulfate coatings either through heterogeneous uptake of gaseous SO2and subsequent oxidation or through coagulation with cloud or fog droplets. The presence of the mixed particles in sulfate droplets also indicates that aggregation of particles of different origins occurred through cloud processing. Such sulfate-coated dust particles would affect cloud formation, precipitation, and chemistry of the free troposphere.