Experimental Study of Sedimentary Oxygen Demand in Lakes: Dependance on Near-Bottom Flow Velocities And Sediment Properties

Sedimentary oxygen demand, SOD, is the uptake of dissolved oxygen, DO, by chemical and biological processes in the uppermost portion of lake sediments. The oxygen is removed from the water column by chemical oxidation processes and by respiration of the microbial population in the sediments. Low DO kills fish in lakes and ponds, especially under ice cover, and increases nutrient release rates from the sediments. To develop DO models and to effectively counteract oxygen depletion an improved understanding of SOD is required. In this study we have investigated SOD through a series of laboratory experiments. We have shown that SOD, frequently the major oxygen consumer in lakes, increases proportionally to the velocity with which the water above the sediments moves. This velocity dependent relationship has, however, an upper bound which depends on the sediment material. The results given in this report allow a more realistic estimation of oxygen demand in lake oxygen models (budgets).