关键词: 傅里叶变换红外光谱技术/
二氧化碳/
稳定同位素比值/
柱浓度
English Abstract
Detection of stable isotopic ratio of atmospheric CO2 based on Fourier transform infrared spectroscopy
Shan Chang-Gong1,2,Wang Wei2,
Liu Cheng3,
Xu Xing-Wei2,
Sun You-Wen2,
Tian Yuan2,
Liu Wen-Qing2
1.School of Environment science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230000, China;
2.Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China;
3.School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230000, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant Nos. 41405134, 41775025, 41575021, 91544212, 41605018), the Natural Science Foundation of Anhui Province, China (Grant No. 1608085MD79) and the National Key Technology RD Program of China (Grant No. 2016YFC0200800).Received Date:15 June 2017
Accepted Date:17 July 2017
Published Online:05 November 2017
Abstract:Long-term measurement of CO2 and its stable isotopes not only obtain the CO2 sources and sink information, but also determine the contributions of different emission sources to atmospheric CO2.Fourier transform infrared spectroscopy (FTIR) is an important technique which can provide highly precise remote sensing of column abundances of atmospheric trace gases.In the study,the stable isotopes of atmospheric CO2,13CO2 and 12CO2,are retrieved from the near-infrared solar absorption spectra collected by a ground-based high-resolution Fourier transform spectrometer. Three spectral windows of 13CO2 and two spectral windows of 12CO2 are chosen to retrieve the two species.The root mean square spectral fitting residuals are about 1.2%,2.3% and 1.2% for the three spectral windows of 13CO2,and about 0.64% and 0.60% for the two spectral windows of 12CO2,respectively.The small spectral fitting residuals indicate the high-quality spectral fitting.The mean retrieval errors are (1.180.27)% and (0.890.25)% for 13CO2 and 12CO2 during the experiment,respectively.The measurement precision of carbon isotopic ratio 13C for the observation system is estimated to be about 0.041 based on the Allan variance method,comparable to the precision of in situ FTIR measurement.Moreover,long time series of atmospheric 13C in one year from September 18,2015 to September 24,2016 is obtained.The results show that atmospheric 13C varies from -7.58 to -11.66,and the mean value is about (-9.50.57) over the duration of the experiment.Also,time series of carbon isotopic signature 13C has an obvious seasonal trend,with a minimum of (-9.350.47) in winter and a maximum of (-8.730.39) in summer. The further analysis suggests that the increase of emission from the fossil fuel burning due to heating may explain the depletion of heavy isotope 13CO2 in winter.Additionally,it is revealed that the variation range of atmospheric 13C observed in Hefei area is consistent with the reported values in Nanjing area based on in situ measurement,while 13C values in summer and winter are higher than the corresponding values detected in Beijing area as indicated in recent publications,which may result from the fact that the CO2 emissions from the fossil fuel combustion in Beijing are more than those in Hefei.The experimental results demonstrate the ability of the ground-based high-resolution FTIR to detect the stable isotopes of atmospheric CO2,13CO2 and 12CO2,and carbon isotopic ratio 13C with a high precision and accuracy.
Keywords: Fourier transform infrared spectroscopy/
stable isotopic ratio/
carbon dioxide/
column abundance
