China
Africa
Explore chapters and articles related to this topic
Surface water and the atmosphere
Published in Ian Acworth, Investigating Groundwater, 2019
The infrared gas analyzer works by emitting an infrared beam of light and monitoring the spectrum of the returned beam. The spectrum can be used to determine CH4, CO2 and H2O gas concentrations.
Effect of small water retention structures on diffusive CO2 and CH4 emissions along a highly impounded river
Published in Inland Waters, 2018
Lluís Gómez-Gener, Marina Gubau, Daniel von Schiller, Rafael Marcé, Biel Obrador
At each SWRS, we determined the partial pressure of CO2 and CH4 in the water (, ) and in air (, ) at the same location as we took the flux measurements. We measured the with an infrared gas analyser (EGM-4, PP-Systems, USA) coupled to a membrane contactor (MiniModule, Liqui-Cel, USA). The water was circulated by gravity through the contactor at 300 mL min−1, and the equilibrated gas was continuously recirculated into the infrared gas analyser for instantaneous measurements (Teodoru et al. 2010). Measurement accuracy of the infrared gas analyser is estimated to be within 1% over the calibrated range. We determined the by the headspace equilibrium technique and gas chromatography described by Striegl et al. (2012). Briefly, we collected 40 mL of water with a 60 mL polypropylene syringe creating a headspace with ambient air of 3:2 ratio (water sample to ambient air). To facilitate the kinetics of equilibration between the liquid and the gas phase, we vigorously shook the syringe for 1 min and then submerged it for 30 min at constant water temperature. We then transferred the 20 mL of equilibrated gas to a preevacuated gas-tight glass tube (Exetainers, Labco Limited, UK). The CH4 samples were analysed in the laboratory with a gas chromatograph coupled to a Flame Ionization Detector (Trace GC Ultra, Thermo Fisher Scientific, USA). Measurement accuracy of the gas chromatograph is estimated to be within 4% over the calibrated range. For and , the air samples were taken ∼1 m above the water surface layer and directly analysed with the infrared gas analyser and the gas chromatographer, respectively.