To understand the characteristics of secondary organic aerosols (SOAs) and estimate their impact on water-soluble organic carbon (WSOC) in urban areas in Japan, we measured 17 organic tracers using gas chromatography–mass spectrometry from particulate matter with an aerodynamic diameter smaller than 2.5 μm collected at five urban sites in Japan during spring and summer. Most anthropogenic, monoterpene-derived, and isoprene-derived SOA tracers showed meaningful correlations with potential ozone in both these seasons. These results indicate that oxidants play an important role in SOAs produced during both seasons in urban cities in Japan. WSOC was significantly affected by anthropogenic and monoterpene-derived SOAs during spring and three SOA groups during summer at most of the sites sampled. The total estimated secondary organic carbons (SOCs), including mono-aromatic, di-aromatic, monoterpene-derived, and isoprene-derived SOCs, could explain the WSOC fractions of 39–63% in spring and 46–54% in summer at each site. Notably, monoterpene-derived and mono-aromatic SOCs accounted for most of the total estimated SOCs in both spring (85–93%) and summer (75–82%) at each site. These results indicate that SOAs significantly impact WSOC concentrations during both these seasons at urban sites in Japan.

中文翻译：

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日本春季和夏季，城市地区PM2.5中的有机分子示踪剂：次生有机气溶胶对水溶性有机碳的影响

为了了解次要有机气溶胶（SOA）的特征并估算其对日本城市地区水溶性有机碳（WSOC）的影响，我们使用气相色谱-质谱法从空气动力学直径小于颗粒直径的颗粒物中测量了17种有机示踪剂在春季和夏季，在日本的五个城市地点收集到2.5μm的水。在这两个季节中，大多数人为，单萜类和异戊二烯类SOA示踪剂均显示出与潜在臭氧的显着相关性。这些结果表明，氧化剂在日本两个城市的两个季节产生的SOA中都起着重要作用。在大多数采样地点，春季的WSOC受人为和单萜来源的SOA的影响很大，夏季时受到三个SOA组的影响。估算的次要有机碳总量（SOCs），包括单芳香族，双芳香族，单萜衍生和异戊二烯衍生的SOC，可以解释每个站点春季的WSOC分数分别为39-63％和夏季的46-54％。值得注意的是，在每个站点的春季（85-93％）和夏季（75-82％）中，单萜类和单芳香族SOC占估计总SOC的大部分。这些结果表明，在这两个季节中，SOA都会显着影响日本城市地区的WSOC浓度。