Real-time observational evidence of changing Asian dust morphology with the mixing of heavy anthropogenic pollution

Abstract

Natural mineral dust and heavy anthropogenic pollution and its complex interactions cause significant environmental problems in East Asia. Due to restrictions of observing technique, real-time morphological change in Asian dust particles owing to coating process of anthropogenic pollutants is still statistically unclear. Here, we first used a newly developed, single-particle polarization detector and quantitatively investigate the evolution of the polarization property of backscattering light reflected from dust particle as they were mixing with anthropogenic pollutants in North China. The decrease in observed depolarization ratio is mainly attributed to the decrease of aspect ratio of the dust particles as a result of continuous coating processes. Hygroscopic growth of Calcium nitrate (Ca(NO3)2) on the surface of the dust particles played a vital role, particularly when they are stagnant in the polluted region with high RH conditions. Reliable statistics highlight the significant importance of internally mixed, ‘quasi-spherical’ Asian dust particles, which markedly act as cloud condensation nuclei and exert regional climate change.

Superposition of Gobi Dust and Southeast Asian Biomass Burning: The Effect of Multisource Long‐Range Transport on Aerosol Optical Properties and Regional Meteorology Modification

“…During the long‐range transport of Asian dust, the properties of dust should be modified due to the passing over vast populous and industrialized areas of the eastern China as well as changes of environmental conditions toward the south (e.g., higher temperature and humidity; Huang et al, ; Pan et al, ; Tobo et al, ). As shown in Figure f, two AERONET sites (i.e., Xianghe in the North China Plain and Taihu in the Yangtze River Delta) located near the dust transport pathway.…”

Variability of depolarization of aerosol particles in Beijing mega city: implication in interaction between anthropogenic pollutants and mineral dust particles

“…CC BY 4.0 License. reactions and its importance between artificial pollution and mineral dust aerosols has also been made and confirmed (Wang et al, 2017).…”

“…backward scattering) decreased as the imaginary part of the refractive index increased (Ishimoto et al, 2010;Dubovik et al, 2006). However, Pan et al (2017) reported that variations in the refractive index of a particle can only explain limited depolarization variability (5%) on the basis of the T-matrix methodology (Dubovik et al, 2002). In other words, the observed change in the depolarization ratio in coarse mode particles in case C was mainly caused by morphological changes.…”

“…Water film also acted as a solute on the dust particles' surface, and the rate of the liquid phase reaction is much higher compared to a gas reaction. Pan et al (2017) demonstrated that the increase of the water vapor content contributed to the decrease of the depolarization ratio of the dust particles in the presence of the Ca(NO3)2 coating. To sum up, after the internal mixing of mineral dust aerosols and anthropogenic pollutants, the hygroscopicity of dust particles increased.…”

An Evaluation of the CHIMERE Chemistry Transport Model to Simulate Dust Outbreaks across the Northern Hemisphere in March 2014

“…This assumption is validated by experimental evidences in many studies [100] and allows a full interaction between all constitutive species of particles. Nevertheless, in this version of CHIMERE the formation of coarse nitrate due to the reaction of calcium with nitric acid (issued from the anthropogenic pollution) is not considered and could enhance the interactions between natural and anthropogenic emissions as it has been studied in China [101]. The transport of "giant" mineral particles, which can be defined as particles with diameters exceeding 10 µm, is rarely documented in the literature according to a recent study [102].…”