| 雪冰中碳质气溶胶含量的测试方法 |
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| 引用本文： | 刘先勤,王宁练,徐柏青.雪冰中碳质气溶胶含量的测试方法[J].冰川冻土,2005,27(2):249-253. |
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| 作者姓名： | 刘先勤 王宁练 徐柏青 |
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| 作者单位： | 1. 中国科学院, 寒区旱区环境与工程研究所, 甘肃, 兰州, 730000;2. 中国科学院, 青藏高原研究所, 北京, 100085 |
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| 基金项目： | 中国科学院知识创新工程项目
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国家自然科学基金 |
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| 摘 要： | 碳质气溶胶是大气气溶胶的一种, 主要由有机碳(OC)和碳黑(BC)或元素碳(EC)组成. 大气中的碳黑因其独特的光学性质和比表面积, 在大气辐射、气候学、云物理学、环境学以及毒物学等研究领域中具有重要的意义. 碳黑的化学性质十分稳定, 可作为一种示踪剂. 雪冰中碳黑记录的研究可以追溯历史时期生物量燃烧的信息, 以及为人类活动污染物的排放研究提供线索. 但是, 目前还没有找到一种十分有效的、统一的方法来测试不同介质中碳质气溶胶的含量. 根据雪冰介质的特点, 设计了一整套碳质气溶胶分析流程及相关的装置. 将雪冰样品融化并通过事先加热处理过的石英膜过滤, 利用供氧两步加热的方法使沉淀在石英膜上的碳质气溶胶中的有机碳和碳黑分离, 两步加热的温度分别为340℃和650℃. 采用分子筛富集CO2, 用FID检测器检测 CO2 含量, 然后换算成有机碳和碳黑的含量. 上述方法测试有机碳和碳黑的空白值分别为6.05μgC和7.12μgC, 相对于国外的空白本底值较高, 主要是由于氧气流中CO2的含量较高所致.
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| 关 键 词： | 热分析方法 雪冰 碳质气溶胶 |
| 文章编号： | 1000-0240(2005)02-0249-05 |
| 收稿时间： | 2004-07-15 |
| 修稿时间： | 2004年7月15日 |
Analyzing Method of Carbonaceous Aerosol in Snow and Ice |
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| LIU Xian-qin,WANG Ning-lian,XU Bai-qing.Analyzing Method of Carbonaceous Aerosol in Snow and Ice[J].Journal of Glaciology and Geocryology,2005,27(2):249-253. |
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| Authors: | LIU Xian-qin WANG Ning-lian XU Bai-qing |
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| Institution: | 1.Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou Gansu 730000, China;2. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China |
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| Abstract: | Being one of the atmospheric aerosols, black carbon is very significant in the fields of atmosphere radiation, climatology, cloud physics, environment science and toxicology due to its specific character, and thus great emphasis is laid on its research. Although black carbon provides suitable surface for a react of chemical reactions, it itself does not react and keeps chemically unchanged for thousands of years. Therefore, the black carbon concentration in ice core samples can provide valuable information concerning the biomass burning and anthropogenic activity. But till now, there has not yet been a very suitable method adopted to determine the amount of black carbon in snow and ice. In this paper, an optimization of a 2-step thermal method for the determination of organic carbon (OC) and element carbon (EC) or black carbon (BC) concentrations in snow and ice is provided. OC is removed from the snow/ice samples under a pure oxygen flow during the first combustion step, which has been carefully optimized in terms of temperature (340℃) and a duration of 42 min. The remaining carbon content is element carbon during the next combustion step in terms of temperature (650℃) and a duration of 32 min. During the combustion steps, the evolved CO2 is accumulated in two molecular-sieve traps respectively. After completion of the combustion steps, the traps were rapidly heated to 200℃ and the desorbed CO2 is measured with the FID detector, The detection limits of OC and EC are dominated by the variability of the blank loads of the pre-cleaned filters, which are (6.05±0.50(2σ))μgC for OC and (7.12±0.53(2σ))μgC for EC, being relatively higher than those gained by Lavanchy (1999) mainly due to the higher content of CO2 in the pure oxygen flow and higher carbon load during the process of sample treatment. |
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| Keywords: | thermal method snow and ice carbonaceous aerosol |
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