• 关键词：PM₁₀  形貌  元素组成  分形

• 基金项目：教育部新世纪优秀人才计划(NoNCET-06-0120);北京市科技新星A(2006);国家自然科学基金资助项目(No50578012,20407004);霍英东青年教师基金资助项目(No91078);北京市教委项目;北京市重点学科资助项目(NoXK100220555);北京林业大学研究生基金资助项目(No05jj006)

• 陈圆
• 北京林业大学环境科学与工程学院, 省部共建森林培育与保护教育部重点实验室, 北京 100083

• 王毅力
• 北京林业大学环境科学与工程学院, 省部共建森林培育与保护教育部重点实验室, 北京 100083

• 王玉涛
• 武警警种指挥学院, 北京 102202

• 李炯
• 北京林业大学环境科学与工程学院, 省部共建森林培育与保护教育部重点实验室, 北京 100083

• 马钦彦
• 北京林业大学环境科学与工程学院, 省部共建森林培育与保护教育部重点实验室, 北京 100083

• 摘要：研究了北京某高校环境实验室内外空气中PM₁₀的形貌特征与元素组成.结果表明,PM₁₀的FESEM图像中燃煤飞灰的粒子数目最多,且PM₁₀中绝大多数颗粒均小于2.5μm,为大气细粒子.燃煤飞灰的平均粒径最小,烟尘聚集体的平均粒径稍大于矿物颗粒,而且烟尘聚集体和燃煤飞灰算术平均直径均呈现室A外≥室A内>室B内的规律,而矿物颗粒算术平均直径却呈现室A外>室B内>室A内的规律.从室A外到室A内,PM₁₀中烟尘聚集体和燃煤飞灰的数目比例均下降,而矿物颗粒的数目比例却增加了近1倍;从室A外到室B内,PM₁₀中烟尘聚集体数目比例下降了很多,而燃煤飞灰和矿物颗粒的数目比例均增加了.化学组成的聚类分析和三元图分析结果表明,室A外的矿物颗粒主要为钙长石,室A内的矿物颗粒主要为伊/蒙混层矿物、硅酸钙,室B内的矿物颗粒主要为长石类矿物和少量的白云石和石膏,其中的石膏可能是大气中均相与非均相反应的产物.基于FESEM形貌和分形维数的计算结果证明,燃煤飞灰不具有分形特征,而烟尘聚集体和矿物颗粒具有分形特征.矿物颗粒的Dsub>1均小于烟尘聚集体Dsub>1,其边界的不规则程度低,而矿物颗粒的Dsub>2均远大于烟尘聚集体Dsub>2,其具有更为密实的结构.

• Abstract：Field emission scanning electron microscopy (FESEM) and energy dispersive X-ray spectrometry (EDX) were used to study the morphology and elemental composition of indoor and outdoor PM₁₀ in the air of environmental laboratories at the campus of a university in Beijing. FESEMimages showed that the sizes of most particles were less than 2.5μm and coal fly ash was the most abundant species in PM₁₀. The arithmetic average diameter of soot aggregates was a little larger than mineral particles, and coal fly ash was the smallest ones among the collected PM₁₀. As for soot aggregates and coal fly ash, particles collected in the outdoor air of Room Awere a little larger than those collected in the indoor air, while the smallest ones were collected in the air of Room B. The largest mineral particles were also found in the outdoor air of Room A. Moreover, both the number percentages of soot aggregates and coal fly ash in outdoor PM₁₀ of Room Awere less than those in indoor PM₁₀, while the number percentage of mineral particles in outdoor PM₁₀ of Room Awas higher than that in indoor PM₁₀. In Room B, the number percentage of soot aggregates in indoor PM₁₀ was much less than that in outdoor PM₁₀ of Room A, while the number percentages of other two particles in indoor PM₁₀ were higher than those in outdoor PM₁₀ of Room A. Cluster analysis of element composition showed that mineral particles could be divided into six groups and mainly constituted of Si, Al and Ca elements. Then with triangle plots analysis, the anorthite was determined to be the primary component of the mineral particles in the outdoor air of Room A, and mixed-layer clays and Ca₂SiO₄ were the main minerals in the indoor air of Room A, and many feldspar mineral particles and a little CaCO₃ and CaSO₄ particles were observed in the indoor air of Room B. Morphology of FESEMimages and fractal dimension calculation indicated that coal fly ash was not fractal, but soot aggregates and mineral particles were fractals. The 1-D_f ractal dimensions of mineral particles were less than those of soot aggregates, which indicated that the boundary of soot aggregates was more irregular. However, the much smaller 2-D_f ractal dimensions for soot aggregates than mineral particles revealed their looser structure.

• Key words：PM₁₀  morphology  elemental composition  fractal

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