Diurnal Variations in the Rate of Gas Exchange between Lake Baikal and the Atmosphere

The diurnal course of gas exchange between Lake Baikal and the atmosphere during the summer warming up is calculated using the data of continuous 102-hour observations in August 2000 and the published materials of individual diurnal measurements of the dissolved gases concentrations made in different years. The diurnal course of the rate of gas exchange in both the coastal and open parts of the lake is found to be due to the fact that slow gas-exchange processes fail to compensate fast changes in the partial pressures of gases dissolved in the upper water layer. The changes are associated with the diurnal dynamics of the hydrometeorological conditions and the intensity of the production-destruction processes. It is found that under light winds, the contribution of biological factors to the formation of short-period variations in the CO2 and O2 fluxes through the lake water surface makes about 80% and that of abiotic factors, 20%. Considerable aperiodic changes in the diurnal course of hydrometeorological conditions are found to essentially distort the normal diurnal course of the gas-exchange processes.