Global environment and climate change are the focus and frontier subjects of ecology, biogeochemistry and environmental science. Simultaneous in-situ monitoring of multiple atmospheric pollution components base on laser absorption spectroscopy technology has become an effective way for in-depth analysis and accurate identification of atmospheric pollution sources by analyzing the correlation of their concentration data. In view of the wide variety of actual atmospheric pollutants, the source, transformation mechanism, and transportation process of each component are extremely complex and overlap phenomenon, the in-depth analysis of atmospheric pollution sources is an important challenge. The depth analysis of air pollution sources is the key basis for scientific control of the air pollution. It is of great significance to carry out in situ monitoring techniques and analytical algorithms for various pollutants. In this paper, carbon monoxide (CO), a typical pollutant in the atmosphere, is firstly selected and analyzed by using HYSPLIT backward trajectory model, and the reliability of the proposed algorithm is verified. In addition, with PM2.5 as the analysis target, the backward trajectory of air mass during 72 h of pollution was simulated by HYSPLIT model for Beijing's heavy pollution during January 26-28, 2020. The potential transport channels and pollution contribution sources of PM2.5 in different areas to Beijing were analyzed by daily trajectory clustering analysis.
Methane (CH4), a key greenhouse by influencing tropospheric ozone (O3) and stratospheric water vapor (H2O), plays an important role on the process of global warming and climate change. In this paper, we report on the development of a gas sensing technique based on high sensitive tunable diode laser absorption spectroscopy (TDLAS). A room-temperature distributed-feedback (DFB) diode laser near 1653 nm is used to excite the rotational-vibrational absorption line of CH4 molecule. Direct absorption spectroscopy and wavelength modulation spectroscopy were used for investigating methane molecular line parameters and sensing gas concentration, respectively. Moreover, potential strategies for sensitivity improvement are also discussed.
Quartz enhanced photoacoustic spectroscopy (QEPAS) is an extremely effective tool for the detection and quantification of trace gases, which offers advantages of fast response, high sensitivity and high resolution. In this paper, a gas sensor based on quartz-enhanced photoacoustic detection and an external cavity quantum cascade laser (ECQCL) was realized and characterized for acetone measurement. Photoacoustic signal dependence on gas pressure and laser operating parameters were studied to optimize sensor performance. In addition, potential approaches and detection schemes on improving sensor performance were also discussed.
A new type of tunable diode spectroscopy sensor based on an external cavity quantum cascade laser (ECQCL) and a quartz crystal tuning fork (QCTF) were used for quantitative analysis of volatile organic compounds. In this work, the sensor system had been tested on different gasoline sample analysis. For signal processing, the self-established interpolation algorithm and multiple linear regression algorithm model were used for quantitative analysis of major volatile organic compounds in gasoline samples. The results were very consistent with that of the standard spectra taken from the Pacific Northwest National Laboratory (PNNL) database. In future, The ECQCL sensor will be used for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis, etc.
Breath analysis is an attractive method for disease diagnosis and therapeutic monitoring, due to its high potential for non-invasive medical diagnostics. Among numerous analysis techniques, tunable diode laser-based absorption spectroscopy (TDLAS) is an excellent method for detection of gas concentration, since it presents advantages of high sensitivity, good selectivity, fast response and high temporal resolution. In this study, state-of-the-art quantum cascade laser based gas sensor is demonstrated as a promising new tool for noninvasive, real-time identification and quantification of trace gases in human breath for clinical uses. Details of selection of spectroscopic parameters and primary lab studies conducted on CO, H2O and N2O molecules in exhaled breath are presented, together with suggestions on the future direction of this challenging analytical field.
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