GC-PDHID法观测我国本底大气中H2浓度

The reaction of hydrogen with hydroxyl radical (OH) is an important sink of atmospheric OH radicals, which could affects the balance of atmospheric photochemical reactions. Because the reaction of methane (CH4) with OH radical is the primary sink for atmospheric CH4, the consumption of atmospheric OH radicals via reaction with H2 can increase the lifetime of CH4. Thus atmospheric H2 has been considered as an important indirect greenhouse gas. However, until now there is no background atmospheric H2 research program carried out in China. In order to recognize the concentration level of atmospheric H2 in background areas of China, high precision H2 analysis system will be developed with configuration of a GC equipped with a pulsed discharge helium ionization detector (PDHID). The research will mainly focus on optimizing the factors that affecting the system precision such as baseline noise and standard gases calibration. The analytical precision will meet the requirement of WMO/GAW target for atmospheric background measurements. The analysis method will improve the capability of trace gases observation and will help to establish the standard procedure of background atmospheric H2 measurement in China. H2 concentrations in flasks weekly sampled from 2 ~ 4 typical background stations will be measured for at least 2 years by using the system developed in this project. In addition to the H2 concentration and variations, the influence of local source/sink will be also preliminary studied combined with surface wind. The implement of this proposal will provide scientific support on evaluation of the greenhouse gases budget and source/sink variations in China.

大气中H2与•OH反应是•OH的重要汇，对大气光化学反应过程有重要影响，可导致大气CH4这一重要温室气体的寿命增长，因而被认为是重要的间接温室气体，但目前国内尚未开展本底大气中H2浓度的观测研究。本项目以认识我国主要本底区域大气H2浓度为目标，依托实验室现有的气相色谱系统，基于气相色谱-脉冲氦离子化检测器（GC-PDHID）研发大气H2高精度的分析方法，重点解决影响系统分析精度的基线噪声和标校问题，确保分析结果满足WMO/GAW观测精度要求，提升我国对本底大气中痕量气体的观测分析能力，并为建立我国对本底大气中H2浓度的规范化监测提供技术支撑。利用所建可靠分析方法分析我国2 ~ 4个典型大气本底站业务化Flask瓶样品中H2浓度，获取至少2年观测数据，研究我国典型本底区域大气H2浓度水平及变化特征，结合地面风等分析初步探索区域源汇对观测浓度的影响，进而为评估我国温室气体源汇动态变化提供科学依据。

大气中H2是一种重要的间接温室气体。本项目以认识我国本底区域大气H2浓度为目标，依托实验室原有的气相色谱系统，研发基于气相色谱-脉冲氦离子化检测器（GC-PDHID）的大气H2高精度的分析方法，对大气H2连续进样分析精度优于1ppb，分析结果满足WMO/GAW观测精度要求。利用所建可靠分析方法分析我国大气本底站业务化Flask瓶样品中H2浓度，并于2015年开始在北京上甸子站开展现场加密观测，基于观测浓度，研究观测数据的筛分方法，初步认识了我国本底区域H2浓度水平及变化特征。结合地面风局地影响和空气团后向轨迹长距离输送等分析，辅以各站同期业务化Flask样品分析的CO等浓度数据进行同源性研究，探明区域源汇（人为源/自然源）对观测大气H2浓度的影响，为评估我国温室气体源汇动态变化提供科学依据。项目执行期间，发表科技论文9篇，其中SCI论文7篇，形成技术手册2份，正在申请专利3项，培养研究生2名，撰写国家标准1份。项目实施过程中，项目组成员1人荣升正高级职称，1人荣升副高级职称，1名博士生顺利转入博士后流动站开展研究。