Atmospheric aerosol compositions in China: spatial/temporal variability, chemical signature, regional haze distribution and comparisons with global aerosols

X Y Zhang,J Y Sun,Y Q Wang,X C Zhang,T Niu,S L Gong,Y M Zhang

doi:10.5194/acp-12-779-2012

X Y Zhang, J Y Sun + Show 5 more

Open Access

https://doi.org/10.5194/acp-12-779-2012

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Abstract

Abstract. From 2006 to 2007, the daily concentrations of major inorganic water-soluble constituents, mineral aerosol, organic carbon (OC) and elemental carbon (EC) in ambient PM10 samples were investigated from 16 urban, rural and remote sites in various regions of China, and were compared with global aerosol measurements. A large difference between urban and rural chemical species was found, normally with 1.5 to 2.5 factors higher in urban than in rural sites. Optically-scattering aerosols, such as sulfate (~16%), OC (~15%), nitrate (~7%), ammonium (~5%) and mineral aerosol (~35%) in most circumstance, are majorities of the total aerosols, indicating a dominant scattering feature of aerosols in China. Of the total OC, ~55%–60% can be attributed to the formation of the secondary organic carbon (SOC). The absorbing aerosol EC only accounts for ~3.5% of the total PM10. Seasonally, maximum concentrations of most aerosol species were found in winter while mineral aerosol peaks in spring. In addition to the regular seasonal maximum, secondary peaks were found for sulfate and ammonium in summer and for OC and EC in May and June. This can be considered as a typical seasonal pattern in various aerosol components in China. Aerosol acidity was normally neutral in most of urban areas, but becomes some acidic in rural areas. Based on the surface visibility observations from 681 meteorological stations in China between 1957 and 2005, four major haze areas are identified with similar visibility changes, namely, (1) Hua Bei Plain in N. China, and the Guanzhong Plain; (2) E. China with the main body in the Yangtze River Delta area; (3) S. China with most areas of Guangdong and the Pearl River Delta area; (4) The Si Chuan Basin in S.W. China. The degradation of visibility in these areas is linked with the emission changes and high PM concentrations. Such quantitative chemical characterization of aerosols is essential in assessing their role in atmospheric chemistry and weather-climate effects, and in validating atmospheric models.

Highlights

Tropospheric aerosols are highly variable in time and space from US (Malm and Schichtel, 2004;Tanner et al, 2004), Europe (Querol et al, 2004, 2008; Yin and Harrison, 2008), S
This paper presents a data set on major inorganic watersoluble constituents, mineral aerosol and carbonaceous species (OC and elemental carbon (EC)) in daily ambient PM10 samples measured from 2006 and 2007 at 16 stations of the Chinese Meteorological Administration (CMA) Atmosphere Watch Network (CAWNET), covering seasonal variations on a longer basis, which is essential to accurately and objectively assess the impacts of various aerosols in China and their influences at regional and global scales
Ca is mainly associated with mineral aerosol in the PM10 samples; but non-crustal Ca is found in the coarse particle fraction, most of which is expected to be from construction activities and coal-ash (Zhang et al, 2002)

Summary

Introduction

Tropospheric aerosols are highly variable in time and space from US (Malm and Schichtel, 2004;Tanner et al, 2004), Europe (Querol et al, 2004, 2008; Yin and Harrison, 2008), S. Asia (Rastogi and Sarin, 2005; Kumar et al, 2007; Stone et al, 2010) to China (Zhang et al, 1993; He et al, 2001; Hu et al, 2002; Zhang et al, 2002; Yao et al, 2002; Ye et al, 2003; Zhang et al, 2008a), and contain optically-scattering sulfate, organic carbon (OC), nitrate, ammonium product, and mineral aerosol in most circumstance, as well as optically-absorbing materials, mainly elemental carbon (EC) with partial contributions from mineral aerosol (Zhang et al, 2008b; Yang et al, 2009). 4.7 3.3 2.9 0.38 0.60 0.35 nd nd a Other WSIC: other water-soluble inorganic cation, including Ca2+, K+, Mg2+ and Na+; b Trace element, including Ni, Cu, Zn, As, Se, Br, Sr, Zr, Pb; c Aerosol acidity: median value of the ratio between NH4+obs (observed NH4+ in μmole m−3) and NH4+neu (the NH+4 amount needed to fully neutralize the measured SO42− , NO3− and Cl−); d Ionic specie (CaSO4) is included in aerosol acidity estimation; e SRL and AKD data were during summer, 2004 to spring, 2005 from the reference (Qu et al, 2009).

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