Determination of dissolved methane in the Beijing-Hangzhou Grand Canal using automated head space-GC system
WEN Jun1, ZANG Kun-peng1,2, PAN Feng-mei1, SHEN Xiao-long1, WEI Kang-xuan1, LAN Wen-gang1, HU Zhi-wei1, CHEN Xiao-ming1, CHEN Bing-jiang1, LI Shan1, LU Yan-ran1, CHEN Li-han1, GUO Peng1, FANG Shuang-xi1,2, LIN Yi1,2, CHEN Yuan-yuan1,2, LIU Shuo1,2, XU Hong-hui3
1. College of Environment Sciences, Zhejiang University of Technology, Hangzhou 310014, China; 2. Zhejiang Carbon Neutral Innovation Institute, Zhejiang University of technology, Hangzhou 310014, China; 3. Zhejiang Meteorological Science Institute, Hangzhou 310008, China
Abstract：A new head-space gas chromatography system equipped with a flame ionization detector and method was self-assembled and established, which could automatically and simultaneously measure concentrations of dissolved methane and carbon dioxide in water samples, with wider linear range and low operating cost. Precision and accuracyof this system for CH4 were better than 0.16% and 0.02%, respectively, which met the measurement requirements. In August 2022, dissolved CH4 concentration and related parameters were observed in the Beijing-Hangzhou Grand Canal in Hangzhou City. Results showed that mean dissolved CH4 concentration was (642.4±423.3) nmol/L, mean saturation was (22310±14701)% and mean air-water CH4 flux was (548.57±603.70)mmol/(m2×d) during field survey, indicated the observed area was a net source of atmospheric CH4. In addition, it was reasonable to estimate that the mean daily release rate of CH4 from the Canal was approximate 1710mol, which was equivalent to 38.31m3 of natural gas or 82.94kg of carbon.
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