Department of Applied Environmental Science, Stockholm University, Stockholm, Sweden.
J Occup Environ Hyg. 2010 Jan;7(1):35-45. doi: 10.1080/15459620903368859.
Elemental carbon has been proposed as a marker of diesel particulate matter. The objective of this study was to investigate if water-soluble carbonaceous compounds could be responsible for positive bias of elemental carbon using NIOSH Method 5040 with a thermo-optical carbon transmittance analyzer. Filter samples from eight different aerosol environments were used: pure diesel exhaust fume with a high content of elemental carbon, pure diesel exhaust fume with a low content of elemental carbon, pure biodiesel exhaust fume, pure woodsmoke, an urban road tunnel, an urban street canyon, an urban background site, and residential woodburning in an urban area. Part of each filter sample was analyzed directly with a thermo-optical carbon analyzer, and another part was extracted with water. This water-soluble extract was filtered to remove particles, spiked onto filter punches, and analyzed with a thermo-optical transmittance carbon analyzer. The ratio of elemental carbon in the water-soluble extract to the particulate sample measurement was 18, 12, and 7%, respectively, for the samples of pure woodsmoke, residential woodburning, and urban background. Samples with diesel particulate matter and ambient samples with motor exhaust detected no elemental carbon in the water-soluble extract. Since no particles were present in the filtered water-soluble extract, part of the water-soluble organic carbon species, existing or created during analysis, are misclassified as elemental carbon with this analysis. The conclusion is that in measuring elemental carbon in particulate aerosol samples with thermo-optical transmittance analysis, woodsmoke, and biomass combustion samples show a positive bias of elemental carbon. The water-soluble EC could be used as a simple method to indicate other sources, such as wood or other biomass combustion aerosol particles.
元素碳被提议作为柴油颗粒物的标志物。本研究的目的是使用 NIOSH 方法 5040 和热光透射碳分析仪，研究水溶性含碳化合物是否会导致元素碳的正偏差。使用了来自 8 种不同气溶胶环境的滤膜样品：高含量元素碳的纯柴油排气烟炱、低含量元素碳的纯柴油排气烟炱、纯生物柴油排气烟炱、纯木柴燃烧产生的烟雾、城市道路隧道、城市街道峡谷、城市背景站点和城市地区的住宅燃烧。每个滤膜样品的一部分直接用热光碳分析仪进行分析，另一部分用水分进行提取。将这种水溶性提取物过滤以去除颗粒，然后在滤膜上添加并使用热光透射碳分析仪进行分析。对于纯木柴燃烧、住宅燃烧和城市背景的样品，水溶性提取物中的元素碳与颗粒样品测量值的比例分别为 18%、12%和 7%。对于含有柴油颗粒物的样品和含有汽车尾气的环境样品，水溶性提取物中未检测到元素碳。由于过滤后的水溶性提取物中没有颗粒，因此在分析过程中存在或生成的部分水溶性有机碳物质会被错误地分类为元素碳。结论是，在用热光透射分析测量颗粒气溶胶样品中的元素碳时，木柴燃烧和生物质燃烧样品会显示出元素碳的正偏差。水溶性 EC 可作为一种简单的方法来指示其他来源，例如木材或其他生物质燃烧气溶胶颗粒。
