Chemical Characteristics and Sources of Submicron Particles in a City with Heavy Pollution in China

Jianlei Lang,Shuiyuan Cheng,Hanyu Zhang,Dongsheng Chen,Ying Zhou,Haiyan Wang,Yanyun Zhang,Shengyue Li

doi:10.3390/atmos9100388

Abstract

Submicron particle (PM1) pollution has received increased attention in recent years; however, few studies have focused on such pollution in the city of Shijiazhuang (SJZ), which is one of the most polluted cities in the world. In this study, we conducted an intensive simultaneous sampling of PM1 and PM2.5 in autumn 2016, in order to explore pollution characteristics and sources in SJZ. The results showed that the average mass concentrations of PM1 and PM2.5 were 70.51 μg/m3 and 91.68 μg/m3, respectively, and the average ratio of PM1/PM2.5 was 0.75. Secondary inorganic aerosol (SIA) was the dominant component in PM1 (35.9%) and PM2.5 (32.3%). An analysis of haze episodes found that SIA had a significant influence on PM1 pollution, NH4+ promoted the formation of pollution, and SO42− and NO3− presented different chemical mechanisms. Additionally, the results of source apportionment implied that secondary source, biomass burning and coal combustion, traffic, industry, and dust were the major pollution sources for SJZ, accounting for 45.4%, 18.9%, 15.7%, 10.3%, and 9.8% of PM1, respectively, and for 42.4%, 18.8%, 12.2%, 10.2%, and 16.4% of PM2.5, respectively. Southern Hebei, mid-eastern Shanxi, and northern Henan were the major contribution regions during the study period. Three transport pathways of pollutants were put forward, including airflows from Shanxi with secondary source, airflows from the central Beijng–Tianjin–Hebei region with fossil fuel burning source, and airflows from the southern North China Plain with biomass burning source. The systematic analysis of PM1 could provide scientific support for the creation of an air pollution mitigation policy in SJZ and similar regions.

Highlights

With the rapid development of the economy and acceleration of urbanization, fine particulate matter pollution is gradually attracting attention in China [1,2,3,4,5]
PM1 concentration rises (Figure 3a), with a mean value of 0.75, indicating the important role PM1 played in PM2.5 pollution, especially for polluted periods
By summarizing previous studies (Figure 3b) it becomes clear that the percentage of PM1 in PM2.5 generally rose as a function of PM1 concentration, and the ratio in SJZ was higher than in most of the cities

Summary

Introduction

With the rapid development of the economy and acceleration of urbanization, fine particulate matter pollution is gradually attracting attention in China [1,2,3,4,5]. Issues related to submicron particles (PM1 , particles with aerodynamic diameters less than or equal to 1 μm) have become more severe in recent years. PM1 has been characterized by high mass concentration and high proportion in PM2.5 [6,7,8], and some major components were more distributed in PM1 than in PM1–2.5 (e.g., NH4 + , SO4 2− , and K+ ), which played prominent roles in haze episode formation in. China [8,9]. PM1 has had a serious impact on air quality, especially for heavy pollutions. The mitigation of PM1 pollution deserves special attention. The chemical characteristics and sources of PM1 should be investigated, in order to provide scientific support for policy making

Methods

Results

Conclusion