Study on the mechanisms of the 2〜3 year variation in the increasing trend of oxidant in the urban air

城市空气中氧化剂2-3年增长趋势变化机制研究

• 批准号: 16510006
• 负责人: NAGAO Ippei
• 金额: $ 2.43万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2004
• 资助国家: 日本
• 起止时间: 2004 至 2006
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16510006/
• 关键词: Ozone in the urban air; 2〜3year oscillation; Ozone precursors; Photochemical reactions; transport processes; Column amount of ozone

(1) Collection and analyses of datasets for atmospheric pollutants and meteorological elementsWe obtained the atmospheric pollutants datasets of Aichi prefecture from 1991 to 2001 as well as the meteorological datasets at Nagoya. We identified the period when this variation was well defined (1985-1998). Since temporal variation in the oxidant concentration in Nagoya was closely related with that in ozone (O_3), this 2-3 year variation in oxidant can be regarded as that in O_3 in Nagoya. In addition, the precursors of O_3 such as NO_x and NMHC (total) were also collected and analyzed to find the similar variations in their trends.(2) Analyses of 03 dataset in the free troposphere over Japan and in the marine boundary layer over the western North PacificSurface O_3 concentration is controlled by in-situ photochemical reactions and transport of the O_3 in the overlying free troposphere. In summer, O_3 in Nagoya can be also affected by the transport of O_3 from the North Pacific. Therefore we analyzed the behaviors in the O_3 concentrations in the free troposphere and at the Ogasawara Island between 1994 and 1997.(3) Measurements of C_2~C_<11> NMHCs in NagoyaTo understand the variation in the photochemical processes in O_3 production, it is required to variation in the individual component of NMHCs. We developed the continuous measurement system of each NMHC component (C_2-C_<11>) with GC/FID and air sampling device, and obtained the NMHC data fro C_2-C_<11>. In particular, the ratio of NMHC/NOx increased in spring and summer could be explained by an increase emission of biogenic NMHC (isoprene), and this result will be helpful to investigate the mechanism.We have not yet revealed the mechanisms of 2-3 year variation in oxidant in urban air. Now we are investigating the differences in the processes between the well-defined periods and the not defined periods to reveal the factors controlling this variation.

(1)大气污染物和气象要素数据集的收集与分析获得了1991-2001年爱知县大气污染物数据集和名古屋气象数据集。我们确定了这种变异被很好地定义的时期(1985-1998)。由于名古屋氧化剂浓度的时间变化与臭氧(O_3)浓度的时间变化密切相关，因此，这种2-3年的氧化剂浓度变化可视为名古屋臭氧浓度的变化。(2)对日本上空自由对流层和北太平洋西部海洋边界层03资料的分析表明，地面O_3浓度受上覆自由对流层中O_3的就地光化学反应和输运控制。在夏季，名古屋的臭氧也会受到北太平洋臭氧输送的影响。因此，我们分析了1994-1997年间自由对流层和小川岛O_3浓度的变化。(3)名古屋C_2~C&t；11&GT；NMHC的测量为了了解O_3产生过程中光化学过程的变化，需要了解NMHC的单个组分的变化。利用GC/FID和空气采样器研制了各NMHC组分(C_2-C_&t；11&gt；)的连续测量系统，获得了C_2-C_&t；11&gt；的NMHC数据。特别是，春季和夏季NMHC/NOx比值的增加可以用生物源NMHC(异戊二烯)排放量的增加来解释，这一结果将有助于研究其机理。我们尚未揭示城市空气中氧化剂2-3年变化的机制。现在，我们正在调查明确定义的周期和未定义的周期之间的过程差异，以揭示控制这种变化的因素。