Morphology, composition and mixing state of individual carbonaceous aerosol in urban Shanghai
Morphology, composition and mixing state of individual carbonaceous aerosol in urban Shanghai
复制标题
上海城区碳质气溶胶形态、组成及混合状态
DOI：
10.5194/acp-12-693-2012
复制
发表时间：
2012-01-01
影响因子：
6.3
通讯作者：
Wang, W.
中科院分区：
文献类型：
--
作者：
Fu, H.;Zhang, M.;Wang, W.
中国说，2010年10月至11月期间，上海市区共收集到了834个气溶胶颗粒。在不同的天气和空气质量条件下对颗粒物进行采样。用透射电子显微镜(TEM)和能量色散X射线(EDX)联用技术研究了碳质气溶胶的形态、组成和混合状态。用选区电子衍射仪(SAED)对部分粒子的结构进行了验证。在所观察到的气溶胶颗粒中，碳质气溶胶主要分为四种类型：聚合物、碳烟、焦油球和生物源颗粒。根据详细的TEM-EDX分析，大多数颗粒被二次有机气溶胶(SOA)包裹，这种二次有机气溶胶通常是通过前体气体在预先存在的颗粒上发生冷凝或多相反应而形成的。老化粒子与风速较低的天数有关，结构复杂，尺寸较大。硫酸盐、有机物和烟尘的内部混合颗粒是常见的。这种内部混合的颗粒可能优先在严重污染事件期间的停滞气团期间形成，例如在11月13日。虽然不同物种的相对数量有所不同，但在样品中观察到的最主要的物种是硫酸盐(38-71%)和烟尘(11-22%)。然而，在11月12日沙尘暴期间采集的样本中，土壤来源的颗粒(68%)相对更常见。
A total of 834 individual aerosol particles were collected during October and November 2010 in urban Shanghai, China. Particles were sampled under different weather and air quality conditions. Morphologies, compositions and mixing states of carbonaceous aerosols were investigated by transmission electron microscopy (TEM) coupled with energy-dispersive X-ray (EDX). Structures of some particles were verified using selected-area electron diffraction (SAED). Among the aerosol particles observed, carbonaceous aerosols were mainly categorized into four types: polymeric organic compound (POC), soot, tar ball, and biogenic particle. Based on the detailed TEM-EDX analysis, most of the particles were coated with secondary organic aerosols (SOA), which commonly formed through condensation or heterogeneous reactions of precursor gases on preexisting particles. Aged particles were associated with days with low wind velocities, showed complex structures, and were bigger in size. The internally mixed particles of sulphates, organics and soot were encountered frequently. Such internally mixed particles may be preferentially formed during a stagnated air mass during serious pollution events, such as on 13 November. Although relative number counts varied with different species, sulphates (38-71 %) and soot (11-22 %) constituted the most dominant species observed in the samples. However, soil-derived particles (68 %) were relatively more frequently observed on the sample collected on 12 November during a dust storm.