Microscopic comparison of aerosol particles collected at an urban site in North China and a coastal site in Japan

Liang Xu; Daizhou Zhang; Weijun Li

doi:10.1016/j.scitotenv.2019.03.163

Microscopic comparison of aerosol particles collected at an urban site in North China and a coastal site in Japan

Sci Total Environ. 2019 Jun 15:669:948-954. doi: 10.1016/j.scitotenv.2019.03.163. Epub 2019 Mar 12.

Authors

Liang Xu¹, Daizhou Zhang², Weijun Li³

Affiliations

¹ Environment Research Institute, Shandong University, Jinan 250100, China; Department of Atmospheric Sciences, School of Earth Sciences, Zhejiang University, Hangzhou 310027, China.
² Faculty of Environmental and Symbiotic Sciences, Prefectural University of Kumamoto, Kumamoto 862-8502, Japan.
³ Department of Atmospheric Sciences, School of Earth Sciences, Zhejiang University, Hangzhou 310027, China. Electronic address: liweijun@zju.edu.cn.

PMID: 30970461
DOI: 10.1016/j.scitotenv.2019.03.163

Abstract

In order to understand the physicochemical properties of aerosol particles in Japan and China, transmission electron microscopy was used to analyze individual aerosol particles collected at two very different environmental sites, i.e., a continental site (T1) in North China and a coastal site (T2) in Japan in springtime. The average PM_2.5 concentration (52μg/m³) at T1 was much higher than T2 (20μg/m³) from 20 to 23 March 2014. Our study shows that sulfur-organic matter (S-OM) particles were the most abundant at both T1 and T2, and individual spherical primary organic matter (POM) particles were only observed at T1. More anthropogenic fly ash and metal particles were observed at T1, consistent with the heavier air pollution at T1 than T2, and the overall complexity of aerosol composition at T1 exceeded that at T2, due to the influence of regional industrial emissions. Further examination of S-OM particles suggest that S-OM coated particles accounted for 29.6% of total observed particles at T2 but only 8.6% at T1. However, the average thickness of OM coating was larger at T2 than at T1, indicating that the particles at T2 had aged longer than those at T1. These comparisons suggest that the OM coating thickness on sulfate depends on the transport distance of the air mass and on the concentration of atmospheric oxidants but should not be used to represent pollution levels. Compared with the coastal air in Japan, we know that urban aerosol particles in North China not only attain high concentrations but also have more complex aerosol components.

Keywords: Composition; East Asia; Individual aerosol particles; Mixing state; Transmission electron microscopy.