大气CO2同位素比值（δ13C-CO2）是定量分析不同生态系统间CO2变迁强度的有力工具，也是了解全球碳循环过程和预测未来全球大气CO2增减的重要依据，因此，检测大气CO2同位素比值是当前大气和生态科学的重要研究内容之一。目前探测大气CO2同位素比值的分析方法，大多采用现场采样离线分析的方法，难以实现大气CO2同位素实时信息的精确获取。鉴于此，本项目提出一种大气CO2同位素比值红外光谱高精度定量分析新方法，通过实验和理论分析，研究不同碳同位素的红外吸收特性，探索仪器效应、环境参数、气体吸收干扰导致光谱发生展宽和漂移等非线性变化的影响机制，在此基础上，研究基于非线性最小二乘法的大气CO2同位素比值的反演算法，通过构建适用于大气CO2同位素比值的FTIR测量系统，实现大气CO2同位素比值的高精度实时在线测量。通过本项目的研究，为大气CO2同位素比值的实时监测奠定方法和技术基础。

The 13C/12C ratio of atmospheric CO2 (δ13C-CO2) is a powerful tool to quantify CO2 flux strength of different ecosystem compartments,which is especially important in understanding the global carbon cycle and in predictions of the future uptake or release of CO2 in the global environment. So detecting isotope abundance which is one research contents of atmospheric and ecological science is basis to determine source and sink of carbon element. Currently, most analysis methods of detecting atmosphere carbon dioxide isotope ratio are sampling and off-line analysis methods, so the real-time information of atmospheric CO2 isotope can't be accurately acquired. In view of this, this project proposes a new high precision quantitative analysis method for atmospheric CO2 isotope ratio by infrared spectrum. Through experiment and theory analysis, the different carbon isotope absorption characteristics in infrared spectrum will be studied. Instrument effect, environment parameters, gas absorption interference, these influence mechanism which lead to spectrum broadening and shift will be explored. On this basis, the inversion algorithm of atmospheric CO2 isotope ratio based on nonlinear least squares method will be studied. The FTIR measurement system which is suitable for atmospheric CO2 isotope ratio analysis will be established, and finally realize atmospheric CO2 isotope ratio high precision, real time and on-line measurement. Through this project, the method and technology for atmospheric CO2 isotope ratio real time measurement will be improved.