BIOLOGICAL SOURCE OF HEAT IN LAKE-BOTTOM SEDIMENTS

Abstract

The metabolic activity of bacteria in bottom sediments produces degradation of organic matter, generates new cellular biomass, liberates heat. Let us estimate the strength of this biological heat source by using data from Lake Kubenskoye. We write the unsteady-state heat conduction equation for a thermally active layer of bottom sediments with a volumetric biological source qv(y) assuming an arbitrary distribution of that source in the sediments. We found that the temperature of the sediment at its interface with the water column is practically identical to the mean water temperature in a shallow lake. This conclusion remains valid for sediment with a biological heat source of realistic strength. The calculation results indicate that with a relatively low concentrations of bacteria in the bottom sediments, the relative rise in temperature and the increase in the heat content of the sediment as a result of the activity of the biological heat source will be considerable if the layer containing the biological source is thick. But in the case of a rather active biological source its contribution to the temperature and heat content of the sediments will be comparable in magnitude to the heating produced by heat transfer from the water column, even if we assume that anaerobic fermentation occurs preferentially in the bottom sediments.