National Ocean Sciences Accelerator Mass Spectrometry Facility, Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, United States.
Environ Sci Technol. 2012 Feb 7;46(3):1422-9. doi: 10.1021/es2043189. Epub 2012 Jan 23.
Analyzing the radiocarbon ((14)C) content of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate matter can provide estimates on the source contributions from biomass burning versus fossil fuel. The relative importance of these two sources to ambient PAHs varies considerably across regions and even countries, and hence there is a pressing need to apportion these sources. In this study, we advanced the radiocarbon analysis from bulk carbon to compound class specific radiocarbon analysis (CCSRA) to determine Δ(14)C and δ(13)C values of PAHs in PM(2.5) samples for investigating biomass burning and fossil fuel source contributions to PAHs from one of the Southeastern Aerosol Research and Characterization (SEARCH) sites in North Birmingham (BHM), Alabama during winter (December 2004-February 2005) and summer (June-August 2005) by accelerator mass spectrometry. To compare our ambient samples to known sources, we collected and analyzed fenceline samples from the vicinity of a coke plant in BHM. As expected, PAHs from the coke plant fenceline samples had very low radiocarbon levels. Its Δ(14)C varied from -990 to -970‰, indicating that 97 to 99% were of fossil source. PAHs in the ambient PM(2.5) had Δ(14)C from -968 to -911 ‰, indicating that 92-97% of PAHs were from fossil fuel combustion. These levels indicated the dominance of fossil sources of ambient PAHs. The radiocarbon level of ambient PAHs was higher in winter than in summer. Winter samples exhibited depleted δ(13)C value and enriched Δ(14)C value because of the increased contribution of PAHs from biomass burning source. However, biomass burning contributed more to heavier PAHs (modern source accounting for 6-8%) than lighter ones with a modern contribution of 3%.
分析大气颗粒物中多环芳烃（PAHs）的放射性碳（^14C）含量可以估算生物质燃烧和化石燃料对环境 PAHs 的源贡献。这两个来源对环境 PAHs 的相对重要性在不同地区甚至国家都有很大差异，因此迫切需要对这些来源进行分配。在这项研究中，我们将放射性碳分析从总碳推进到化合物类别特定的放射性碳分析（CCSRA），以确定 PM（2.5）样品中 PAHs 的Δ^14C 和 δ^13C 值，以研究伯明翰（BHM）北东南气溶胶研究和特征（SEARCH）站点之一冬季（2004 年 12 月至 2005 年 2 月）和夏季（2005 年 6 月至 8 月）生物质燃烧和化石燃料对 PAHs 源的贡献，使用加速器质谱法。为了将我们的环境样品与已知来源进行比较，我们从 BHM 附近的一个焦炭厂收集并分析了围栏线样品。正如预期的那样，来自焦炭厂围栏线样品的 PAHs 具有非常低的放射性碳水平。其Δ^14C 从-990 到-970‰不等，表明 97%至 99%来自化石源。环境 PM（2.5）中的 PAHs 的Δ^14C 为-968 到-911‰，表明 92%至 97%的 PAHs 来自化石燃料燃烧。这些水平表明环境 PAHs 的化石源占主导地位。与夏季相比，冬季环境 PAHs 的放射性碳水平更高。冬季样品的 δ^13C 值减少，Δ^14C 值增加，因为生物质燃烧源的 PAHs 贡献增加。然而，生物质燃烧对较重的 PAHs（现代源占 6-8%）的贡献大于较轻的 PAHs，现代源的贡献为 3%。
