title: Size, composition, and mixing state of individual aerosol particles in a South China coastal city.
abstract: 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 microm. 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.
authors.affiliation: State Key Laboratory of Coal Resources and Safe Mining & College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing 100083, China. liweijun@sdu.edu.cn
authors.forename: Weijun
authors.initials: W
authors.lastname: Li
authors.forename: Longyi
authors.initials: L
authors.lastname: Shao
authors.forename: Zhishi
authors.initials: Z
authors.lastname: Wang
authors.forename: Rongrong
authors.initials: R
authors.lastname: Shen
authors.forename: Shusheng
authors.initials: S
authors.lastname: Yang
authors.forename: Uwa
authors.initials: U
authors.lastname: Tang
mesh_terms: D000336:Aerosols; D000392:Air Movements; D000393:Air Pollutants / Q000737:chemistry*; D002681:China; D002947:Cities; D004784:Environmental Monitoring; D052638:Particulate Matter / Q000737:chemistry*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D052638:Particulate Matter