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首页> 外文期刊>Atmospheric chemistry and physics >Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles
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Combustion characteristics of water-insoluble elemental and organic carbon in size selected ambient aerosol particles

机译：大小选定的环境气溶胶颗粒中水不溶性元素碳和有机碳的燃烧特性

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Combustion of elemental carbon (EC) and organic carbon (OC) contained in ambient aerosolmatter was explored using scanning electron microscopy (SEM) in combination with energy dispersiveX-ray analysis (EDX). To ease identification of the particles of interest and to avoid or at least reduceinteraction with simultaneously sampled inorganic oxides and salts, the approach used in this workdiffered in two ways from commonly applied procedures. First, rather than using a mixture of particles ofvastly different sizes, as in PM10 or PM2.5, aerosol matter was collected in a 5-stage impactor. Second,the water soluble fraction of the collected matter was removed prior to analysis. Diesel soot particles,which appeared in the well-known form of chain-type aggregates, constituted the major fraction of EC. Incontrast, OC containing particles were observed in a variety of shapes, including a sizable amount ofbioaerosol matter appearing mostly in the size range above about 1 µm. During heating in ambient air for1h, diesel soot particles were found to be stable up to 470°C, but complete combustion occurred ina narrow temperature interval between about 480 and 510°C. After diesel soot combustion, minutequantities of "ash" were observed in the form of aggregated tiny particles with sizes less than 10 nm.These particles could be due to elemental or oxidic contaminants of diesel soot. Combustion of OC wasobserved over a wide range of temperatures, from well below 200°C to at least 500°C. Incompletely burntbioaerosol matter was still found after heating to 600°C. The results imply that the EC fraction in aerosolmatter can be overestimated significantly if the contribution of OC to a thermogram is not well separated.
机译：使用扫描电子显微镜（SEM）结合能量色散X射线分析（EDX），探索了环境气溶胶中所含元素碳（EC）和有机碳（OC）的燃烧。为了简化目标颗粒的识别并避免或至少减少与同时采样的无机氧化物和盐之间的相互作用，本工作中使用的方法与常用方法有两种不同。首先，不是像PM10或PM2.5中那样使用大小不同的颗粒混合物，而是在5级撞击器中收集气溶胶物质。第二，在分析之前将收集到的物质中的水溶性部分除去。柴油机烟灰颗粒以众所周知的链型聚集体形式出现，是EC的主要部分。相反，观察到含OC的颗粒呈各种形状，包括相当数量的生物气溶胶物质，大部分出现在大约1 µm以上的尺寸范围内。在环境空气中加热1小时的过程中，发现柴油烟灰颗粒在470°C的温度下是稳定的，但在大约480至510°C的狭窄温度范围内发生了完全燃烧。柴油机烟灰燃烧后，观察到“灰”的微小量为聚集的细小颗粒，尺寸小于10 nm。这些颗粒可能是由于柴油机烟灰的元素或氧化性污染物引起的。在远低于200°C至至少500°C的温度范围内观察到OC的燃烧。加热至600°C后仍发现不完全燃烧的生物气溶胶物质。结果表明，如果OC对热谱图的贡献没有很好地分离，则气溶胶物质中的EC分数可能会被高估。

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