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首页> 外文期刊>Atmospheric chemistry and physics >Effective densities of soot particles and their relationships with the mixing state at an urban site in the Beijing megacity in the winter of 2018
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Effective densities of soot particles and their relationships with the mixing state at an urban site in the Beijing megacity in the winter of 2018

机译：2018年冬季北京市北京市北京市北京市场地区烟灰粒子及其与搅拌状态的有效密度

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The effective density (ρeff) of refractory black carbon (rBC) is a key parameter relevant to its mixing state that imposes great uncertainty in evaluating the direct radiation forcing effect. In this study, a tandem differential mobility analyzer–centrifugal particle analyzer–single-particle soot photometer (DMA–CPMA–SP2) system was used to investigate the relationship between the effective density (ρeff) and the mixing state of rBC particles during the winter of 2018 in the Beijing megacity. During the experiment, aerosols with a known mobility diameter (Dmob) and known ρeff values (0.8, 1.0, 1.2, 1.4, 1.6, and 1.8 g cm?3) were precisely selected and measured by the SP2 to obtain their corresponding mixing states. The results showed that the ρeff well represented the morphological variation in rBC-containing particles. The rBC-containing particles changed from an irregular structure to a compact spherical structure with the increase in ρeff. A ρeff value of 1.4 g cm?3 was the morphological transition point. The morphology and ρeff value of the rBC-containing particles were intrinsically related to the mass ratio of non-refractory matter to rBC (MR). As the ρeff values of the rBC-containing particles increased from 0.8 to 1.8 g cm?3, the MR of the rBC-containing particles significantly increased from 2 up to 6–8, indicating that atmospheric aging processes were likely to lead to the reconstruction of more compact and regular particle shapes. During the observation period, the ρeff of the majority of rBC-containing particles was smaller than the morphology transition point independent of the pollution conditions. This suggested that the major rBC-containing particles did not have a spherical structure. Simulation based on an aggregate model considering the morphological information of the particles demonstrated that absorption enhancement of rBC-containing particles could be overestimated by ～ 17 % by using a core–shell model. This study highlights the strong dependence of the morphology of ambient rBC-containing particles on ρeff and will be helpful for elucidating the microphysical characteristics of rBC and reducing uncertainty in the evaluation of rBC climate effects and health risks.
机译：难熔黑碳（RBC）的有效密度（ρeff）是与其混合状态相关的关键参数，其在评估直接辐射迫使效果方面施加了很大的不确定性。在该研究中，使用串联差分迁移率分析仪离心粒子分析仪 - 单粒子光度计（DMA-CPMA-SP2）系统来研究冬季中RBC颗粒的有效密度（ρeff）和混合状态之间的关系2018年在北京的巨大心理。在实验期间，精确地选择具有已知迁移率直径（DMOB）的气溶胶（DMOB）和已知的ρeff值（0.8,1.0,1.2,1.4,1.6和1.8g和1.8g和1.8g，1.6g，1.6克，1.6克，1.6克，1.6和1.8g。结果表明，ρeff良好地代表了含RBc颗粒的形态变化。含RBC的颗粒从不规则结构变为紧凑的球形结构，随着ρeff的增加。 Peff值为1.4克厘米？3是形态过渡点。含RBC颗粒的形态和ρAff值与RBC（MR）的非耐火材料的质量比固有。由于含RBc颗粒的ρeff值从0.8升至1.8g cm = 3，含RBc的颗粒MR可显着增加到6-8，表明大气老化过程可能导致重建更紧凑且常规的粒子形状。在观察期间，大多数含RBC颗粒的ρeff小于污染条件的形态转变点。这表明含有主要RBC的颗粒没有球形结构。考虑到颗粒的形态学信息，基于聚集模型的仿真表明，通过使用核心壳模型，可以通过〜17％的含RBc颗粒的吸收增强。该研究突出了含有环境RBC颗粒的形态对ρeff的强烈依赖性，并有助于阐明RBC的微神科特征，并降低RBC气候影响和健康风险评估中的不确定性。

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