SEDIMENT OXYGEN-DEMAND MODEL - METHANE AND AMMONIA OXIDATION

A model of sediment oxygen demand is presented that relates the sediment oxygen demand (SOD) to the extent of oxidation of dissolved methane and ammonia generated in the anaerobic zone of the sediment of lakes and streams. The fluxes of dissolved methane and ammonia from the sediment to the overlying water, as well as methane and nitrogen gas fluxes that escape as bubbles, are included in the model. The three model parameters—the dissolved methane mass transfer coefficient and the two oxidation rate parameters—are estimated from laboratory and field data sets. The effect of overlying water dissolved oxygen and temperature is examined. The importance of the gas fluxes and their quantitative relationship to SOD is established. Any field program that includes the measurement of SOD should also include the measurement of the nitrogen and methane fluxes as well. The model is limited to freshwater sediments since the oxidation of sulfides is not included. The contribution from the respiration of benthic macro fauna is also not incorporated. © ASCE.