compound class specific AMS 14C analysis

采用化合物类别特异性放射性碳分析（CCSRA）方法，对日本东京郊区一个居民区大气颗粒物（&lt;10μm PM<10>_2和&lt;1.1μm PM<1.1>_3）中的多环芳烃（PAHs）进行了分析，并研究了其季节和粒径的变化。PM_2和PM_3中的多环芳烃总浓度（38种3-6个芳香环的化合物之和）分别为0.94-3.25 ng/m^3<10>和0.69-2.68 ng/m^3<1.1>。来源诊断异构体对比率表明，混合的贡献，从石油燃烧和生物质和煤燃烧的多环芳烃在APM。APM中Δ^ C-PAHs的含量<14>在-787 ~-514‰之间，表明化石燃料燃烧的影响占主导地位。PM_2<14>和PM_3中5-6环（HMW）多环芳烃的Δ^ C均高于3-4环（LMW）<10><1.1>多环芳烃。HMW-PAHs的Δ^<14>C表明夏季生物质燃烧的贡献大于冬季，且没有明显的粒径变化。相反，<14>低分子量物质的Δ^ C在夏季和较大的颗粒物（PM_）中表现出更大的贡献<10>。这一发现可以初步归因于化石多环芳烃从石油源蒸发的再冷凝。A ^<14>C同位素质量平衡法估计，生物质燃烧贡献了东京郊区17%至45%的多环芳烃负担，生物质多环芳烃的增加分别占冬季LMW和HMW-PAH升高的27%和22%。这些结果远远超过了日本CO_2和燃烧物排放统计的预期值，强调了生物质燃烧作为多环芳烃污染源的重要性，从而证明了CCSRA对多环芳烃污染进行现场源评价的实用性和重要性。

Compound class specific radiocarbon analysis (CCSRA) was performed for polycyclic aromatic chydrocarbons (PAHs) associated with airborne particulate matter (APM) with diameter <10μm (PM_<10>) and <1.1μm (PM_<1.1>) collected from a residential area of suburban Tokyo, Japan and seasonal and particle-size radiocarbon variations were investigated. Total PAHs concentrations (sum of 38 compounds with 3-6 aromatic rings) ranged 0.94-3.25 ng/m^3 for PM_<10> and 0.69-2.68 ng/m^3 for PM_<1.1> samples. Source diagnostic isomer pair ratios indicated mixed contributions from petroleum combustion and from biomass and coal combustion to the PAHs in APM. The Δ^<14>C-PAHs in APM ranging from -787 to -514‰ indicated dominance of fossil fuel combustion. The Δ^<14>C of 5-6 rings (HMW) PAHs were higher than the 3-4 rings (LMW) species in both PM_<10> and PM_<1.1> samples. The Δ^<14>C of HMW-PAHs indicated greater biomass-burning contributions in summer than in winter and no apparent particle-size variation. Conversely, the Δ^<14>C of LMW species showed a greater contribution from fossil sources in summer and in larger particles (PM_<10>). This finding could be tentatively attributed to the recondensation of fossil-PAHs vaporized from petroleum sources. A ^<14>C isotopic mass balance approach estimated that biomass burning contributes 17 to 45% of the PAH burden in suburban Tokyo, and that the increase in the biomass-PAH accounts for approximately 27% and 22% of winter-time elevation of LMW- and HMW-PAHs, respectively. These are far exceeding what is expected from the emission statistics for CO_2 and combusted materials in Japan and emphasizing the importance of biomass-burning as a source of PAHs ; which, in turn, demonstrates the utility and the significance of field-based source assessment by using CCSRA for an effective regulation of atmospheric pollution by PAHs.