A study on formation process of anthropogenic organic aerosol using a highly advanced mass spectrometer

1.气溶胶质谱仪(AMS)准确度的提高AMS的粒子收集效率取决于样品空气中的相对湿度(RH)。AMS进气歧管的温度保持在环境露点以上&gt；10℃，以防止样品空气中的干燥颗粒(进气中的RH为53%)。假设AMS的CE=0.5，AMS测得的无机物种(硝酸盐、硫酸盐、氯化物和铵)的质量浓度与离子色谱分析仪(PILS-IC)测得的质量浓度在~20%以内。选定有机化合物的质谱分析我们评估了选定的低分子二元酸(二酸)对AMS质谱图的m/z 44信号的贡献。我们使用了在东京获得的环境测量数据和使用选定有机酸的真实标准获得的实验室实验数据。我们首次报道了在测量期间，所选择的有机酸平均可以占到观测到的m/z 44信号的14%。东京人为有机气溶胶的季节和日变化调查在东京的一个城市现场进行了痕量气体和气溶胶的现场测量。根据与一氧化碳(CO)的相关性，将有机气溶胶(OA)分为初级有机气溶胶(POA)和次级有机气溶胶(SOA)。我们发现POA在夏季、秋季和冬季没有明显的日变化，而SOA表现出明显的日变化。我们还发现，在高光化学活性的条件下，在~0.5d内可以显著提高OA的浓度。

1. Improvement of the accuracy of the Aerosol Mass Spectrometer (AMS)The particle collection efficiency (CE) of the AMS depends on relative humidity (RH) in sample air. The temperature of the AMS inlet manifold was maintained at > 10℃ above the ambient dew point to dry particles in the sample air (RH in the inlet < 53%). Assuming CE = 0.5 for the AMS, the mass concentrations of inorganic species (nitrate, sulfate, chloride, and ammonium) measured by the AMS agree with those measured by an Ion Chromatography analyzer (PILS-IC) to within 〜20%.2. Analysis of the mass spectra of selected organic compoundsWe have evaluated the contribution of selected low molecular weight dicarboxylic acids (diacids) to the m/z 44 signal of the AMS mass spectrum. We used ambient measurement data obtained in Tokyo and laboratory experiment data obtained using authentic standards of the selected organic acids. We have reported for the first time that the selected organic acids could account for 14% of the observed m/z 44 signal on average during the measurement period.3. Investigation of the seasonal and diurnal variations of anthropogenic organic aerosol in TokyoIn situ measurements of trace gases and aerosols were conducted at an urban site in Tokyo. Organic aerosol (OA) is classified into primary organic aerosol (POA) and secondary organic aerosol (SOA) using correlation with carbon monoxide (CO). We have found that POA does not exhibit a distinct diurnal variation for the summer, fall, and winter periods, while SOA shows a clear diurnal pattern. We have also found that the OA concentrations can be significantly enhanced within 〜0.5 days under conditions of high photochemical activity.