title: In situ measurements of dissolved gases (CO2 and CH4) in a wide range of concentrations in a tropical reservoir using an equilibrator.
abstract: An equilibrator system connected to an infrared photo acoustic gas analyzer was used in order to measure directly in situ the concentrations of dissolved CO2 and CH4 in waters of a tropical reservoir (Petit Saut, French Guiana). The performance of the system was tested both on a vertical profile in the stratified water body of the reservoir and in the surface waters of the river downstream the dam. Results agreed with conventional GC analysis at +/-15% in a wide range of concentrations (CO2:50-400 micromol l-1 and CH4:0.5-350 micromol l-1 corresponding to gas partial pressures of respectively 1700-13,000 and 12-8800 microatm). The time needed for in situ measurements was equivalent to water sampling, time for GC analysis in the laboratory being suppressed. The continuous monitoring of gas concentrations for 24 h in the reservoir surface waters revealed rapid changes in concentrations highly significant in the daily emission budget. The system opens new perspectives for the monitoring of gas concentrations in highly dynamic systems like tropical reservoirs.
authors.affiliation: Université Bordeaux 1, CNRS-UMR EPOC 5805, Avenue des Facultés, F 33405 Talence, France. g.abril@epoc.u-bordeaux1.fr
authors.forename: Gwenaël
authors.initials: G
authors.lastname: Abril
authors.forename: Sandrine
authors.initials: S
authors.lastname: Richard
authors.forename: Frédéric
authors.initials: F
authors.lastname: Guérin
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods*; D005618:Fresh Water / Q000032:analysis; D017752:Greenhouse Effect; D008697:Methane / Q000032:analysis*; D014329:Tropical Climate; D014881:Water Supply / Q000032:analysis
chemical_list: D002245:Carbon Dioxide; D008697:Methane