QUANTIFYING THE EFFECT OF OXIDATION ON LANDFILL METHANE EMISSIONS

Field, laboratory, and computer modeling methods were utilized to quan titatively assess the capability of aerobic microorganisms to oxidize landfill-derived methane (CH4) in cover soils. The investigated munici pal landfill, located in Nashua, New Hampshire, was operating without gas controls of any type at the time of sample collection. Soil sample s from locations of CH4 flux to the atmosphere were returned to the la boratory and subjected to incubation experiments to quantify the respo nse of oxidation in these soils to temperature, soil moisture, in situ CH4 mixing ratio, soil depth, and oxygen. The mathematical representa tions of the observed oxidation reponses were combined with measured a nd predicted soil characteristics in a computer model to predict the r ate of CH4 oxidation in the soils at the locations of the measured flu xes described by Czepiel et al. [this issue]. The estimated whole land fill oxidation rate at the time of the flux measurements in October 19 94 was 20%. Local air temperature and precipitation data were then use d in conjunction with an existing soil climate model to estimate an an nual whole landfill oxidation rate in 1994 of 10%.