Seasonal variations of water-soluble ions in PM10 at a WMO/GAW station in the Yangtze River Delta, China

Dongqing Fang,Junli Jin,Junshan Jing,Rui Hao,Wei Huang,Peng Yan,Wanqi Sun,Yong Zhang,R Weerasinghe,J Wu,C.-H Weng

doi:10.1051/e3sconf/202019404058

Abstract

In order to understand the seasonal levels, formation mechanism and atmospheric chemical behaviours of water-soluble ions of PM10 in the Yangtze River Delta (YRD) region, aerosol samples were collected from January 2nd to December 28th, 2017 at a WMO/GAW regional background station in Lin’an. The concentrations of PM mass and nine water-soluble inorganic ions were obtained. The annual average concentration of PM10 was 59.9±33.9 μg m−3, lower than those reported in previous studies, indicating air quality of YRD region was improved. Nine water-soluble inorganic ions was accounted for 30.2-45.1% of the total PM mass, while ammonium (NH4+), sulfate (SO42+), as well as nitrate (NO3-) were the major ions which contributed 86.3% to total ions. The NO3- concentration was lowest in summer but highest in winter, suggesting it was likely influenced by thermodynamics. The levels of SO42- in spring and winter were related to photochemical reaction and regional transportation. Except for the SNA, Ca2+ was highest in four seasons likely due to sand storm and road fugitive dust. The annual mean ratio of [NO3-]/[SO42-] was nearly to 1, indicating mobile and stationary sources were equally important in Lin’an. The mean nitrogen oxidation ratio (NOR) and sulfur oxidation ratio (SOR) were 0.22±0.13 and 0.41±0.13, respectively, suggesting secondary formation was significant in the atmosphere at the background station of YRD region.

Highlights

Since the strong link between air pollution and adverse health effects has been revealed, the elevated atmospheric particulate matters especially for inhalable particles have become a public concern due to their abilities to induce chronic respiratory inflammation and acute cardiovascular disease, as well as the obvious impacts on haze formation and climate change [1, 2]
These results showed the air quality of Yangtze River Delta (YRD) region was enhanced in recent years
The lowest concentration in summer may be due to the abundant shower and the actions of rainwash can remove some particles suspended to the atmosphere [12]. 3.2 Characteristics of water-soluble inorganic ions 3.2.1 Mass concentrations

Summary

Introduction

Since the strong link between air pollution and adverse health effects has been revealed, the elevated atmospheric particulate matters especially for inhalable particles (aerodynamic diameter less than 10 μm, PM10) have become a public concern due to their abilities to induce chronic respiratory inflammation and acute cardiovascular disease, as well as the obvious impacts on haze formation and climate change [1, 2]. The three major ions (ammonium (NH4+), sulfate (SO42+), as well as nitrate (NO3-) have been identified as the tracers for secondary inorganic aerosols in previous studies of source apportionment [6]. Huang et al (2012) has demonstrated that secondary inorganic aerosols (SNA) was one of the three sources related with fog haze in the YRD region during field observations, rest of which were biomass burning and long-range transport [7]

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Conclusion