title: Evaluation of two current approaches for the measurement of carbon dioxide diffusive fluxes from lentic ecosystems.
abstract: The dry ice sowing experiment (DISE) consisted in adding dry ice to a lake and monitoring the subsequent evasion of carbon dioxide (CO2). DISE allowed us to evaluate two approaches commonly used for measuring aquatic CO2 diffusive fluxes: the boundary layer equation (BLE) from Cole and Caraco (1998) and a particular model of static chamber (SC). CO2 evasion measurements with both approaches were compared to CO2 mass budgets as a relative reference to define their recovery coefficients (p). p for the BLE and the SC over the whole measurement period were 101 +/- 14% and 115 +/- 56%, respectively. Results from discrete sampling intervals revealed that the BLE generally provided estimations in good agreement (80-130%) with the mass budgets during both daytime and nighttime. Variations in p for the BLE were related to wind speed and, consequently, piston velocity (k600). The SC overestimated CO2 evasion during daytime (149 +/- 39%), and underestimated it during nighttime (57 +/- 18%). Variations in p for the SC were related to k600, stemming mainly from the alteration of the air/ water temperature gradient.
authors.affiliation: GEOTOP/Institut des sciences de l'environnement, Université du Québec a Montréal, C.P. 8 888, Succ. Centre-Ville, Montréal, Québec, Canada H3C 3P8. nicolas.soumis@internet.uqam.ca
authors.forename: Nicolas
authors.initials: N
authors.lastname: Soumis
authors.forename: René
authors.initials: R
authors.lastname: Canuel
authors.forename: Marc
authors.initials: M
authors.lastname: Lucotte
mesh_terms: D002245:Carbon Dioxide / Q000032:analysis*; D004367:Dry Ice; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005618:Fresh Water
chemical_list: D004367:Dry Ice; D002245:Carbon Dioxide