Size, composition, and mixing state of individual aerosol particles in a South China coastal city

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• 作者：Weijun Li ; Longyi Shao ; Zhishi Wang ; Rongrong Shen ; Shusheng Yang ; Uwa Tang
• 关键词：individual aerosol particles ; soot ; heterogeneous reaction ; sea salt
• 刊名：Journal of Environmental Sciences
• 出版年：2010
• 出版时间：2010
• 年：2010
• 卷：22
• 期：4
• 页码：561-569
• 全文大小：1074 K

文摘

Aerosol samples were collected in summer in Macao, a coastal city of the Pearl River Delta Region in China. Morphology, size, elemental composition, and mixing state of individual aerosol particles were determined by scanning electron microscopy coupled energy dispersive X-ray (SEM/EDX) and transmission electron microscopy (TEM). Based on the morphologies of 5711 aerosol particles, they consist of soot (32 % ), mineral (17 % ), secondary (22 % ), and unknown fine particles (29 % ). The sizes of these particles were mostly distributed between 0.1 and 0.4 μm. Compositions of 202 mineral particles were obtained by SEM/EDX. Mineral particles were mainly classified into three types: Si-rich, Ca-rich, and Na-rich. The compositions of typical mineral particles can indicate their sources in sampling location. For example, mineral particles, collected along the main street, were associated with trace amounts of heavy metals, such as Zn, Ti, Mn, Ba, Pb, and As. TEM observations indicate that most Na-rich particles were aged sea salt particles (e.g., Na₂SO₄ and NaNO₃) which formed through heterogeneous chemical reactions between sea salt and acidic gases. Additionally, aging time of soot was short in Macao due to high humidity, high temperature, and high levels of sunlight in Macao. Most of soot and fine mineral dust particles were internally mixed with secondary particles.