Abstract
Sulfate, nitrate and ammonium (SNA) are the dominant composition of secondary aerosols in the atmosphere and have a significant impact on public health, atmospheric chemistry process and climate. In this study, to evaluate SNA pollution in China, a first nationwide investigation derived from almost all published data in the field measurement before 2012 was carried out. The results show that SNA levels in China are about 3–5 times higher than those in USA and Europe. SNA account for 34.2 ± 10.9% in PM2.5 and 28.2 ± 8.5% in PM10. The highest SNA concentrations occur in urban areas of northern China. SNA all have peaks in winter, but the nadirs are in spring for sulfate and ammonium and in summer for nitrate. SOR (sulfur oxidation ratio) and NOR (nitrogen oxidation ratio) values show that the formations of sulfate and nitrate are distinct in different regions and seasons. The low average NO3–/SO42– ratio (0.43 ± 0.26) indicates that the stationary emissions from coal combustion remain the main sources. There is a good relationship between (2[SO42–] + [NO3–]) and [NH4+] with near 1 slope, signifying that (NH4)2SO4 and NH4NO3 are the predominant forms which SNA exist in particles in China. Based on the comprehensive observational data in China, the simulation for SNA aerosols by GISS in CMIP5 were evaluated.
Highlights
Atmospheric particles are complex and consist of all kinds of chemical species which are directly from the natural and anthropogenic emissions or formed as the secondary components (Xu et al, 2012)
Sillanpää et al (2006) suggesting severer SNA pollutions in China. Such high SNA levels can be attributed to higher precursors emissions, e.g., for sulfate, annual average 22.45 Tg SO2 emissions in China (China Statistical Yearbook, 2002–2013) was higher than annual average 11.56 Tg SO2 emissions in USA and 6.78 Tg SO2 emissions in Europe when the territory area of China is comparable to USA and about 2 times of Europe Union countries
We investigate SNA in aerosols in China based on almost all data published before 2012 in the field measurements
Summary
Atmospheric particles are complex and consist of all kinds of chemical species which are directly from the natural and anthropogenic emissions or formed as the secondary components (Xu et al, 2012). Nitrate and ammonium (abbreviated as SNA) are the dominant secondary species of aerosols (~30–50% in PM2.5) They can determine the chemical characteristic of particle by changing particles’ hygroscopicity and acidity, influence the optical properties of particles and the earth’s radiation balance by scattering and absorbing solar radiation, change cloud nucleation process by acting as cloud condensation nuclei (CCN) and affect climate, and the most important, penetrate deeply to human lung and deteriorate human health (Xu et al, 2002; Sun et al, 2004; Cheung et al, 2005; Hu et al, 2008; Pathak et al, 2009; Cheng et al, 2011; Sang et al, 2011; Gao et al, 2012; Yan et al, 2012). Up to now, the nationwide SNA pollution characteristic from the ground observation is still blank
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