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Gu M, Chen J, Zhang Y, Tan T, Wang G, Liu K, Gao X, Mei J. Portable TDLAS Sensor for Online Monitoring of CO 2 and H 2O Using a Miniaturized Multi-Pass Cell. SENSORS (BASEL, SWITZERLAND) 2023; 23:2072. [PMID: 36850670 PMCID: PMC9963767 DOI: 10.3390/s23042072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 02/04/2023] [Accepted: 02/08/2023] [Indexed: 06/18/2023]
Abstract
We designed a tunable diode laser absorption spectroscopy (TDLAS) sensor for the online monitoring of CO2 and H2O concentrations. It comprised a small self-design multi-pass cell, home-made laser drive circuits, and a data acquisition circuit. The optical and electrical parts and the gas circuit were integrated into a portable carrying case (height = 134 mm, length = 388 mm, and width = 290 mm). A TDLAS drive module (size: 90 mm × 45 mm) was designed to realize the function of laser current and temperature control with a temperature control accuracy of ±1.4 mK and a current control accuracy of ±0.5 μA, and signal acquisition and demodulation. The weight and power consumption of the TDLAS system were only 5 kg and 10 W, respectively. Distributed feedback lasers (2004 nm and 1392 nm) were employed to target CO2 and H2O absorption lines, respectively. According to Allan analysis, the detection limits of CO2 and H2O were 0.13 ppm and 3.7 ppm at an average time of 18 s and 35 s, respectively. The system response time was approximately 10 s. Sensor performance was verified by measuring atmospheric CO2 and H2O concentrations for 240 h. Experimental results were compared with those obtained using a commercial instrument LI-7500, which uses non-dispersive infrared technology. Measurements of the developed gas analyzer were in good agreement with those of the commercial instrument, and its accuracy was comparable. Therefore, the TDLAS sensor has strong application prospects in atmospheric CO2 and H2O concentration detection and ecological soil flux monitoring.
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Affiliation(s)
- Mingsi Gu
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
| | - Jiajin Chen
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Yiping Zhang
- Anhui Advanced Spectroscopy Optical-Electric S&T Co., Ltd., Hefei 230026, China
| | - Tu Tan
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Guishi Wang
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Kun Liu
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
| | - Xiaoming Gao
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
- Science Island Branch of Graduate School, University of Science and Technology of China, Hefei 230026, China
| | - Jiaoxu Mei
- Anhui Institute of Optics and Fine Mechanics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei 230031, China
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Temporal Variation and Source Analysis of Atmospheric CH4 at Different Altitudes in the Background Area of Yangtze River Delta. ATMOSPHERE 2022. [DOI: 10.3390/atmos13081206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
Through an analysis of CH4 data observed at different altitudes at the atmospheric background station in Lin’an from 2016 to 2020, in combination with back-trajectory and distribution characteristics of potential source areas, the CH4 concentration variations at higher and lower altitudes and their relationships with sources and sinks were studied. The results showed that the CH4 concentration was characterized by notable diurnal variations. The largest concentration difference occurred between 5 and 7 am; the concentration difference in summer was higher than that in the other three seasons. Background filtering of the hourly CH4 concentration was carried out using a numerical method. The results showed that the difference in the CH4 background concentration between the two altitudes was 4.6 ppb (SD = 7.9). The CH4 background concentrations at the two altitudes had the same seasonal variation: double peaks and valleys. The peaks appeared in May and December, and the valleys appeared in March and July. In spring and summer, the potential CH4 source areas were mainly distributed in the rice planting and wetland discharge regions. In autumn, they were mainly distributed in regions affected by fugitive emissions from rice planting and coal mining. In winter, they were mainly distributed in livestock and poultry management regions.
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