The emission fluxes and the distribution of dissolved methane (CH4) and carbon dioxide (CO2) were determined for 11 sampling stations in two hydroelectric reservoirs (flooded since 1978 and 1993) located in the James Bay territory of northern Québec. The measured benthic fluxes for the two greenhouse gases were found to be either higher or similar to those determined at the water‐air interface during the ice‐free sampling periods. For the 2 year duration of the study, emission fluxes of CH4 to the atmosphere generally varied between 5 and 10 mg m−2 d−1, while those for CO2 ranged from 500 to 1100 mg m−2 d−1. Furthermore, through the use of static chambers at the water‐air interface, we determined that the emission fluxes for the gases are controlled by molecular diffusion. Our calculated fluxes have been separated into two groups: (1) regular emission fluxes and (2) above‐average emission fluxes. The first type comprises the majority of fluxes measured during the sampling periods (i.e., 88% for CH4 and 87% for CO2). The second group reflects unusual sampling conditions (e.g., strong winds, water column depths of less than 1 m, or flooded peatland mats floating at the surface). Although data for this group are limited, our preliminary results suggest that they may be an important component in an atmospheric emissions budget for large reservoirs. Concentration profiles for CH4 and CO2 dissolved in the water column clearly show that oxidation and/or horizontal advection of these gases are controlling factors in their subsequent release to the atmosphere. Most of the CH4 is oxidized within the first 25 cm above the flooded soil‐water interface. Consequently, neither benthic emissions of CH4 and CO2 nor the type of flooded soil appear to control atmospheric emissions of these gases from hydroelectric reservoirs.

This paper suggests that the potentiometric detection of sulfur oxides in air is feasible with solid‐sulfate electrolytes, and presents experimental results on the electrode Pt, SO2 , O2/SO4= . Several experimental parameters, namely, pSO2 , temperature, and flow rate, are studied with concentration cells using potassium sulfate, as the electrolyte. A solid reference electrode based on an Ag/Ag+ electrochemical couple is also studied as a replacement for the gas reference electrode. The authors conclude that rapid conversion of several gaseous sulfur compounds, namely, H2S , CH3SH , etc., into oxides occurs under the cell operating conditions, and that rapid equilibrium is reached between SO2 , SO3 , and O2 at the electrode. Preliminary results of tests using solid electrolytes to detect other gaseous oxides in air are also given for the Pt, CO2 , O2/CO3= , and Pt, NO2 , O2/NO3− systems.

This paper describes an extended application of potentiometric solid-state detectors for measuring oxides in oxygen-variable gases. The SO2, SO8, 02, Pt/SO4 = system examined in Part I for oxide detection in air is studied here with respect to the total sulfur oxide and oxygen partial pressures. A study of the experimental parameters, operating temperatures, and the oxygen partialpressure range revealed the possibility of a simple method of compensating the effect of the oxygen partial pressure on the signal from the oxide detector. An entirely solid-state device consisting of a potassium-sulfate oxide detector, a stabilized-zirconia oxygen detector, and usual electronic components is described, and results of tests with synthetic gas mixtures are presented. Experimental findings confirm calculations based on the electrode reactions and on the rapidly established equilibrium at the platinum electrode. "* Electrochemical Society Student Member.

The infrared spectra of CH,, at low concentrations in the noble gases, were obtained at temperatures ranging from 4 "K up to the respective boiling points of argon, krypton, or xenon. It is concluded from this study that methane occupies substitutional cavities in these lattices. Furthermore, it is established that the potential hindering the rotation of the molecules perturbs the higher rotational levels to a greater extent than the low lying levels.In a second series of experiments, the methane concentration was varied from 0.06 to 55 % for krypton; narrower ranges were used for argon and xenon. The experimental results clearly demonstrate that the influence of the CH, concentration is different for the three systems and that the fine structure does not result from molecular aggregation.The spectrum of 0.06% CD, in solid krypton shows fine structure which confirms the rotational origin of the four components observed for CH,. The CD, spectra previously published were complicated with additional lines that probably arose from the nonhomogeneity of the samples.Les spectres infrarouges du CH, en faibles concentrations dans les gaz nobles furent enregistres a des temperatures allant de 4 "K jusqu'aux points d'ebullition de I'argon, du krypton ou du xenon. Cette etude nous a permis de conclure que le methane occupe des cavites substitutionnelles dans ces reseaux.On a de plus constate que le potentiel s'opposant a la rotation des molecules se manifeste a un plus haut degrC sur les niveaux de rotation eleves que sur les premiers niveaux.La concentration de methane fut ensuite variCe de 0.06 a 55 % pour le krypton; des domaines moins Ctendus furent utilists pour I'argon ou le xenon. Les rCsultats exptrimentaux obtenus dimontrent clairement que I'effet de la concentration en CH, est different pour les trois systemes et que la structure fine n'est pas causee par I'agglomCration des molCcules.Le spectre du CD, en solution a 0.06% dans le krypton montre une structure fine qui confirme la nature rotationnelle des quatre composantes observees pour le CH,. Les spectres de CD, publies antirieurement Ctaient compliquCs par des raies additionnelles probablement attribuables a I'inhomogtnCitC des Cchantillons.

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