Size distribution of water-soluble inorganic ions in urban aerosols in Shanghai

Developmental Biology

Ye Tao¹  Jianmin Chen¹  Zi Yin¹  Zhen Ma¹  Xingnan Ye¹ 

关键词: Water-soluble ions;    size fraction;    secondary aerosols;    Yangtze River Delta;   

DOI  :  10.5094/APR.2014.073

学科分类：农业科学（综合）

来源: Dokuz Eylul Universitesi * Department of Environmental Engineering

【 摘 要 】

The size distribution of water-soluble inorganic components of urban aerosols in Shanghai was studied. The size-resolved aerosol samples collected by an 8-stage cascade sampler between April and May of 2012 were analyzed by ion chromatography. The ion mass concentrations followed the sequence of SO₄²⁻>NO₃⁻~NH₄⁺>Ca²⁺>Na⁺ ~Cl⁻>K⁺>Mg²⁺>F⁻ for each size fraction below 2.1 μm, while the sequence was NO₃⁻>SO₄⁻²>Ca²⁺>NH₄⁺>Na⁺>Cl⁻>K⁺>Mg²⁺>F⁻ for coarse mode particles larger than 3.3 μm. The size distribution in 5 fractions showed that SO₄²⁻, NO₃⁻, and NH₄⁺ were generally in the fine mode peaking below 1 μm while Ca²⁺, Mg²⁺, Na⁺, and Cl⁻ were bimodally distributed with a second peak larger than 2.1 μm. Back trajectory analyses revealed that the air masses could be classified into three main groups. The total ion concentrations were comparable between the terrestrial and mixing regimes. In the terrestrial regime, fine mode sulfate and nitrate were predominantly associated with ammonium. The excessive sulfate and nitrate over the whole size range might exist in the forms of Ca(NO₃)₂ and CaSO₄. In the maritime regime, the decrease in SO₄²⁻, NO₃⁻, and NH₄⁺ contributed to the improvement in air quality. Besides marine aerosols, local emissions from soil dust and coal combustion were also important sources of sea-salt type ions (i.e., Na⁺ and Cl⁻).

【 授权许可】

Unknown   

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