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Volume 12, No. 6, December 2012, Pages 1237-1246 PDF(501 KB)  
doi: 10.4209/aaqr.2011.11.0224   

Aircraft Measurements of Ionic and Elemental Components in PM2.5 over Eastern Coastal Area of China

Lihong Ren1,2,3,4, Renjian Zhang1, Zhipeng Bai2, Jianhua Chen2, Hongjie Liu2, Meigen Zhang3, Xiaoyang Yang2, Leiming Zhang5

1 Key Laboratory of Regional Climate-Environment for East Asia, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2 State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012, China
3 State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
4 Graduate University of Chinese Academy of Sciences, Beijing 100049, China
5 Air Quality Research Division, Science and Technology Branch, Environment Canada, Toronto, Canada

 

Abstract

 

To understand the ionic and elemental components in PM2.5 over eastern coastal areas in China, aircraft measurements were carried out from 25 December, 2002 to 6 January, 2003. PM2.5 filter samples were collected and analyzed for mass concentrations, nine ionic components and 15 trace elements. The highest concentrations of PM2.5 were observed at the lowest altitudes, indicating the influence of ground-level sources. Sulfate, nitrate and ammonium were the main water-soluble components, and the sum of their concentrations accounted for 60–70% of the total ionic mass. Cl depletion was observed to an extent of 3–26%. Anthropogenic ally derived particles contributed about 60% of the total measured ionic components, and natural sources such as sea salts and soil dusts contributed another 40%. Different to many earlier studies, Ca2+ was found to mainly originate from anthropogenic sources. PM2.5 showed an acidic nature, with a neutralization potential/acidic potential ratio of less than 1.0. NH4+ was the major neutralizer of aerosol acidity. A good correlation was observed between the concentrations of NO3 and nssCa2+, suggesting that photochemically produced HNO3 was partly absorbed by mineral particles. S had the highest concentrations among the 15 elements. The enrichment factor values of the observed elements were all over 1, indicating that all of them were influenced by anthropogenic sources. The enrichment factors of Pb, S, As, Cu and Zn were over 100, and suggesting that they were greatly enriched.

 

 

Keywords: Aircraft measurements; Enrichment factor; Source analysis; Neutralization potential/Acidic potential ratio.

 

 

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