Size distribution of PM20 observed to the north of the Tibetan Plateau

• Published in: Journal of mountain science 2021-02, Vol.18 (2), p.367-376
• Main Authors: Zhou, Cheng-long, Yang, Fan, Huo, Wen, Mamtimin, Ali, Yang, Xing-hua
• Format: Article
• Language: English
• Subjects: Airborne sensing; Atmospheric particulates; Dust; Dust storms; Earth and Environmental Science; Earth Sciences; Ecology; Emission measurements; Environment; Geography; Microbalances; Original Article; Particle size; Particle size distribution; Quartz crystal microbalance; Quartz crystals; Size distribution; Spatial distribution; Wind erosion
• ISSN: 1672-6316; 1993-0321; 1008-2786
• DOI: 10.1007/s11629-020-6086-3

The size distribution of airborne dust particles is an important parameter in the measurement of dust emissions due to wind erosion, and a quantitative and accurate description is necessary. Observations regarding the size distribution of airborne dust particles are currently lacking in Tibetan Plateau (TP). This study aims to obtain a dust particle size distribution and compare the difference in spatial distribution at a field site (FS) and two urban observation sites (Minfeng and Hetian), in the north of the TP, under the condition of the dust-days and clear-days. The observation data was collected from 5 July to 4 August, 2019. The mass concentration of dust (PM 20 ) was measured with a 10-stage quartz crystal microbalance cascade impactor. The results suggested that 91.9% of the particles were less than 1.4 µm on clear-days, and particles of d ≥ 1.4 µm increased to 27.2% with the occurrence of the dust events. More than 80% of the airborne dust particles were less than 1.4 µm for each friction velocity. The proportion of d < 0.7 µm was the greatest at 3.0 m (above the surface, similarly hereinafter) on dust-days, while the proportion of d > 0.7 μm was the greatest at 0.5 m on clear-days. During urban observation, with the occurrence of dust events, the concentration of a particle size greater than 2.5 µm increased most significantly in Minfeng, while the concentration of a particle size less than 0.7 µm increased most significantly in Hetian. Moreover, the proportion of particles with d < 0.7 μm had the smallest difference, while the proportion of particles with d > 1.4 µm had the most obvious difference among these three sites.