Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China
Size-resolved effective density of submicron particles during summertime in the rural atmosphere of Beijing, China
复制标题
中国北京农村大气夏季亚微米颗粒的尺寸分辨有效密度
DOI：
10.1016/j.jes.2018.01.012
复制
发表时间：
2018
影响因子：
6.9
通讯作者：
Min Hu
中科院分区：
文献类型：
--
作者：
Kai Qiao;Zhijun Wu;Xiangyu Pei;Qianyun Liu;Dongjie Shang;Jing Zheng;Zhuofei Du;Wenfei Zhu;Yusheng Wu;Shengrong Lou;Song Guo;Chak K. Chan;Ravi Kant Pathak;Mattias Hallquist;Min Hu
粒子密度是大气粒子的一项重要物理性质。高时间分辨率粒子密度信息对于了解气溶胶粒子的大气物理和化学老化过程至关重要。在本研究中，我们于2016年夏季在北京农村地区使用离心颗粒质量分析仪（CPMA）和差分迁移率分析仪（DMA）来测定50 - 350 nm颗粒的尺寸分辨有效密度。颗粒有效密度随粒径的增大而减小，平均为1.43 ~ 1.55 g/cm3。在50 ~ 350 nm的粒子中，有效粒子密度分布以峰值在1.5 g/cm3左右的模式为主。150、240和350 nm颗粒（可能是新排放的煤烟颗粒）在密集的一次排放事件中观察到1.0、0.8和0.6 g/cm3的额外模式。颗粒有效密度呈日变化规律，白天较高。实例研究表明，在新粒子形成（NPF）过程中，艾特肯模式粒子的有效密度显著降低，表明有机物对新粒子的生长有重要贡献。
Particle density is an important physical property of atmospheric particles. The information on high time-resolution size-resolved particle density is essential for understanding the atmospheric physical and chemical aging processes of aerosols particles. In the present study, a centrifugal particle mass analyzer (CPMA) combined with a differential mobility analyzer (DMA) was deployed to determine the size-resolved effective density of 50 to 350 nm particles at a rural site of Beijing during summer 2016. The measured particle effective densities decreased with increasing particle sizes and ranged from 1.43 to 1.55 g/cm3, on average. The effective particle density distributions were dominated by a mode peaked at around 1.5 g/cm3for 50 to 350 nm particles. Extra modes with peaks at 1.0, 0.8, and 0.6 g/cm3for 150, 240, and 350 nm particles, which might be freshly emitted soot particles, were observed during intensive primary emissions episodes. The particle effective densities showed a diurnal variation pattern, with higher values during daytime. A case study showed that the effective density of Aitken mode particles during the new particle formation (NPF) event decreased considerably, indicating the significant contribution of organics to new particle growth.