Characterisation of individual aerosol particles collected during a haze episode in Incheon, Korea using the quantitative ED-EPMA technique

H. Geng,J. Y. Ryu,C.-U. Ro,S. Maskey,H.-J. Jung

doi:10.5194/acp-11-1327-2011

H. Geng, J. Y. Ryu + Show 3 more

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https://doi.org/10.5194/acp-11-1327-2011

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Abstract

Abstract. A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, was used to analyse individual aerosol particles collected in Incheon, Korea on 13–18 October 2008 (a typical haze episode occurred from 15 to 18 October). Overall 3600 individual particles in PM2.5-10 and PM1.0-2.5 fractions from 12 aerosol samples collected on haze and non-haze days were analysed. The analysed particles were classified, based on their X-ray spectral data together with their secondary electron images. The major particle types included organic carbon (OC), elemental carbon (EC), sea-salt, mineral dust (such as aluminosilicate, SiO2, CaCO3/CaMgCO3, etc.), (NH4)2SO4/NH4HSO4-containing, K-containing, Fe-rich and fly ash particles. Their relative number abundance results showed that OC particles were significantly increased while sea-salts and mineral dust particles were significantly decreased (especially in PM1.0-2.5 fraction) when haze occurred. For the other particle types (except Fe-rich particles in PM2.5-10 fraction), there were no significant differences in their relative abundances between haze and non-haze samples. On non-haze days, the nitrate-containing reacted sea-salt and mineral dust particles in PM1.0-2.5 fraction significantly outnumbered the sulfate-containing ones, whereas it was the reverse on haze days, implying that on haze days there were special sources or formation mechanisms for fine aerosol particles (≤2.5 μm in aerodynamic diameter). The emission of air pollutants from motor vehicles and stagnant meteorological conditions, such as low wind speed and high relative humidity, might be responsible for the elevated level of OC particles on haze days.

Highlights

Urban haze, an atmospheric phenomenon that leads to low visibility, has increased in occurrence over the last several years over the Seoul-Incheon metropolis and other cities in Korea, because of continuous economic growth and the increased consumption of fossil fuels (Lee et al, 2006; Chun and Lim, 2004; Kim et al, 2008)
Particle types that were abundantly observed in the samples were carbonaceous, mineral dust, sea-salt, (NH4)2SO4/NH4HSO4
Was mass concentration of airborne PM10 increased, and the components of aerosol particles were changed in comparison with the non-haze days (Jung et al, 2009; Noh et al, 2004; Hong et al, 2008; Lee et al, 2006)

Summary

Introduction

An atmospheric phenomenon that leads to low visibility, has increased in occurrence over the last several years over the Seoul-Incheon metropolis and other cities in Korea, because of continuous economic growth and the increased consumption of fossil fuels (Lee et al, 2006; Chun and Lim, 2004; Kim et al, 2008). The occurrence of haze is closely related to meteorological conditions and air pollution (Keywood et al, 2003). The formation of haze is favoured by stagnant weather conditions and high emissions of air pollutants (Sun et al, 2006). Urban haze is related to a high level of airborne particles resulting from anthropogenic emission (through industrial and other human activities) and from gas-to-particle conversion (Watson, 2002). Haze alters the composition of airborne aerosols through aqueous phase reactions (Sun et al, 2006), having significant effects on visibility, cloud formation, public health and even the global climate (Davis et al, 2010; Yadav et al, 2003; Menon et al, 2002; Lee and Sequeira, 2001)

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