Wetting properties of fresh urban soot particles: Evaluation based on critical supersaturation and observation of surface trace materials
Wetting properties of fresh urban soot particles: Evaluation based on critical supersaturation and observation of surface trace materials
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新鲜城市烟尘颗粒的润湿特性：基于临界过饱和度和表面微量物质观察的评估
DOI：
10.1016/j.scitotenv.2021.152274
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发表时间：
2022
影响因子：
9.8
通讯作者：
Miura Kazuhiko
中科院分区：
文献类型：
--
作者：
Ueda Sayako;Mori Tatsuhiro;Iwamoto Yoko;Ushikubo Yuta;Miura Kazuhiko
烟尘颗粒强烈吸收太阳辐射并导致全球变暖。此外，排放时烟灰的润湿特性也会影响其使用寿命。我们使用东京测量的数据研究了与新鲜烟灰的润湿和疏水特性相关的表面条件。使用云凝结核 (CCN) 计数器来澄清主要由水不溶性 (WI) 材料组成的颗粒的表面状况：总颗粒和活性颗粒作为 CCN 围绕直径 203 nm 的 WI 颗粒的临界过饱和度 (Sc)。 1.05%过饱和度（SS）下作为CCN的失活颗粒的平均数分数（即Scof亲水性WI颗粒）估计为1.4%。在高峰时段，非活性颗粒的数量分数变化较小，为 1.78%SS，而增加为 0.89%SS，这意味着大多数 WI 颗粒包含少量水溶性 (WS) 材料，而不是完全疏水的。根据对高峰时段收集的样品进行透射电子显微镜 (TEM) 分析，69% 的大部分裸露烟灰颗粒具有 Na 或 K 小区域，被认为源自化石燃料。根据水透析分析结果，烟灰上的部分Na和K是WS。与 CCN 测量的组合结果表明这些 WS 材料降低了烟尘的 Scof。此外，覆盖烟灰表面Na和K区域的硫酸盐形态结构表明烟灰上预先存在的钠和钾化合物是烟灰老化的触发因素。然而，在 TEM 样品上也发现了 atScat 的非活性颗粒、不良亲水颗粒和仅由 WI 材料组成的烟灰颗粒，尽管它们很小。此类颗粒不利于获得可润湿表面，可能在大气中较长时期内保持不吸湿性。考虑烟灰中随着排放而发生的化学成分的细微且不均匀的差异，可以有益于对长程烟灰输送的评估。
Soot particles strongly absorb solar radiation and contribute to global warming. Also, wetting properties of soot at emission can affect its lifetime. We investigated surface conditions related to wetting and hydrophobic properties of fresh soot using data from measurements taken in Tokyo. A cloud condensation nuclei (CCN) counter was used to clarify surface conditions of particles composed mainly of water-insoluble (WI) materials: total and active particles as CCN around critical supersaturation (Sc) of 203-nm-diameter WI particles. Averaged number fractions of inactivated particles as CCN at 1.05% supersaturation (SS), which isScof hydrophilic WI particles, were estimated as 1.4%. Number fractions of inactive particles changed less at 1.78%SS during rush hour and increased at 0.89%SS, implying that most of the WI particles included small amounts of water-soluble (WS) materials rather than being completely hydrophobic. Based on transmission electron microscope (TEM) analysis of samples collected during rush hour, 69% of the mostly bare soot particles had Na or K small domains that are regarded as originating in fossil fuels. Based on water dialysis analysis results, some Na and K on soot were WS. Combination results with CCN measurements suggest that these WS materials decrease theScof soot. Moreover, the morphological structure of sulfate covering Na and K domains on the soot surface implicates pre-existing sodium and potassium compounds on soot as a trigger of soot aging. However, inactive particles atScat poor-hydrophilic particles and soot particles composed solely of WI materials on TEM samples were also found, although they were minor. Such particles, which are unfavorable for obtaining a wettable surface, might retain non-hygroscopicity for a longer period in the atmosphere. Evaluation of long-range soot transport can benefit from consideration of slight and inhomogeneous differences of chemical compounds on soot that occur along with their emission.