National Institute for Environmental Studies, Ibaraki, Japan.
Environ Sci Technol. 2010 Nov 15;44(22):8581-86. doi: 10.1021/es102392r.
Diurnal variations of fossil secondary organic carbon (SOC) and nonfossil SOC were determined for the first time using a combination of several carbonaceous aerosol measurement techniques, including radiocarbon (¹⁴C) determinations by accelerator mass spectrometry, and a receptor model (chemical mass balance, CMB) at a site downwind of Tokyo during the summer of 2007. Fossil SOC showed distinct diurnal variation with a maximum during daytime, whereas diurnal variation of nonfossil SOC was relatively small. This behavior was reproduced by a chemical transport model (CTM). However, the CTM underestimated the concentration of anthropogenic secondary organic aerosol (ASOA) by a factor of 4-7, suggesting that ASOA enhancement during daytime is not explained by production from volatile organic compounds that are traditionally considered major ASOA precursors. This result suggests that unidentified semivolatile organic compounds or multiphase chemistry may contribute largely to ASOA production. As our knowledge of production pathways of secondary organic aerosol (SOA) is still limited, diurnal variations of fossil and nonfossil SOC in our estimate give an important experimental constraint for future development of SOA models.
首次使用多种碳质气溶胶测量技术（包括加速器质谱¹⁴C 测定和受体模型（化学质量平衡，CMB）），结合在 2007 年夏季东京下风处的一个站点，确定了化石二次有机碳（SOC）和非化石 SOC 的日变化。化石 SOC 表现出明显的日变化，白天达到最大值，而非化石 SOC 的日变化相对较小。化学输送模型（CTM）再现了这种行为。然而，该 CTM 低估了人为二次有机气溶胶（ASOA）的浓度达 4-7 倍，表明白天 ASOA 的增强不能用传统上被认为是主要 ASOA 前体的挥发性有机化合物的生成来解释。这一结果表明，未被识别的半挥发性有机化合物或多相化学可能对 ASOA 的生成有很大贡献。由于我们对二次有机气溶胶（SOA）生成途径的了解仍然有限，我们估算中的化石和非化石 SOC 的日变化为 SOA 模型的未来发展提供了重要的实验约束。
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