Measurement of organic mass to organic carbon ratio in ambient aerosol samples using a gravimetric technique in combination with chemical analysis
Measurement of organic mass to organic carbon ratio in ambient aerosol samples using a gravimetric technique in combination with chemical analysis
复制标题
DOI：
10.1016/j.atmosenv.2007.08.023
复制
发表时间：
2007-12-01
影响因子：
5
通讯作者：
Yu, Jian Zhen
中科院分区：
文献类型：
--
作者：
Chen, Xi;Yu, Jian Zhen
有机物质占环境颗粒物质量的很大一部分。量化它们对气溶胶总质量的贡献对于确定气溶胶源和随后制定有效的控制措施是很重要的。有机碳（OC）质量可用气溶胶碳分析仪测定；然而，对于除了c之外还含有N、H和O原子的有机化合物，没有直接测定其质量的方法。通常采用的方法是用OC乘以一个因子来估计有机质量（OM）。然而，由于缺乏适当的OM方法，很少测量这种OC-to-OM倍率。我们在这里报告了一种自上而下的方法，通过耦合热重和化学分析来确定OM。OM是过滤器在空气中以550℃加热4h前后的质量差，减去由于单质碳（EC）、挥发性无机化合物（如NH4NO3）和加热处理引起的气溶胶相关水的损失而造成的质量损失。通过对加热前后过滤器的化学分析，确定了EC和无机化合物的损失量。我们分析了2003年冬季、2004年春季和2005年夏季在香港收集的37个环境气溶胶样本。在这些香港气溶胶样本中，2.1 +/- 0.3是将OC转化为OM的合适因子。如果将优势气团划分为两类，则以大陆气团为主的气溶胶的om / oc比值为2.2，以海洋气团为主的气溶胶的om / oc比值为1.9。(C) 2007 Elsevier Ltd.版权所有。
Organic materials make up a significant fraction of ambient particulate mass. It is important to quantify their contributions to the total aerosol mass for the identification of aerosol sources and subsequently formulating effective control measures. The organic carbon (OC) mass can be determined by an aerosol carbon analyzer; however, there is no direct method for the determination of the mass of organic compounds, which also contain N, H, and O atoms in addition to C. The often-adopted approach is to estimate the organic mass (OM) from OC multiplying by a factor. However, this OC-to-OM multiplier was rarely measured for a lack of appropriate methods for OM. We report here a top-down approach to determine OM by coupling thermal gravimetric and chemical analyses. OM is taken to be the mass difference of a filter before and after heating at 550 degrees C in air for 4h minus mass losses due to elemental carbon (EC), volatile inorganic compounds (e.g., NH4NO3), and loss of aerosol-associated water that arise from the heating treatment. The losses of EC and inorganic compounds are determined through chemical analysis of the filter before and after the heating treatment. We analyzed 37 ambient aerosol samples collected in Hong Kong during the winter of 2003, spring of 2004, and summer of 2005. A value of 2.1 +/- 0.3 was found to be the appropriate factor to convert OC to OM in these Hong Kong aerosol samples. If the dominant air mass is classified into two categories, then an OM-to-OC ratio of 2.2 was applicable to aerosols dominated by continent-originated air mass, and 1.9 was applicable to aerosols dominated by marine air mass. (C) 2007 Elsevier Ltd. All rights reserved.