近海大尺度区域二氧化碳的激光在线探测技术

On-line detection of carbon dioxide in large scale offshore by laser technology

陆地或海洋与大气之间的能量和物质交换的定量研究,特别是二氧化碳(CO2)交换通量的监测,对研究全球碳循环以及气候变化具有重要意义。基于直接吸收光谱技术和导数吸收光谱技术,采用收发一体式光学系统,研制了开放式CO2在线探测样机,测量区域可达到km量级。利用Allan方差分析了系统检测限,当积分时间达到100 s时,检测限为0.08×10-6。使用不同浓度的标准气体,验证了二阶导数光谱用于浓度反演方法的可行性,得到相关性为0.998。样机在深圳市生态环境监测站连续运行1个月,探测结果具有明显的日变化周期性。与安装于附近不同点位的Licor7550-CO2监测仪进行数据对比,数据变化趋势吻合,且样机稳定性更优。

Quantitative research on energy and material exchange between the land or ocean and the atmosphere,especially the monitoring of carbon dioxide(CO2)exchange flux,play an important role in the study of global carbon cycle and climate change.We developed an open-path CO2 detection system based on direct absorption spectroscopy technology and derivative spectroscopy technology for on-line measurement across an order of km air path.A movable platform was developed capable of detecting atmospheric variations of CO2 in real time with the integrated optical system of transceiver.Allan variance analysis shows the detection limit of the system is 0.08×10-6 at the integration time of 100 s.The feasibility of the method with the second derivative spectrum is verified by using standard gases with different concentrations for the concentration calibration,and the correlation is 0.998.The continuous operation was carried out at Shenzhen Eco-environment Monitoring Station for 1 month,and the detection results have obvious daily variation periodicity.Comparing the data with the Licor7550-CO2 monitor installed at different points nearby,the data change trend is consistent,and the stabilityof the prototype is better.