Determination of environmental factors influencing methane oxidation in a sandy landfill cover soil

Abstract

It is advantageous to use coarse soils as landfill cover because they allow better aeration of the biologically active zone. In this study, therefore, patterns of methane oxidation were investigated under various environmental conditions including sod moisture content, temperature, and the addition of NH4+ in a sandy landfill cover soil. The kinetics of CH, oxidation was also studied at different moisture contents and temperatures. Soil moisture content of 10% (wt/wt) resulted in the maximum CH, oxidation rate (19.2-22.4 nmol g(soil DW)(-1) min(-1)). A V-max value was not significantly different when the moisture content was more than 10%, but a K. value increased from 5.23 to 75.24 mu M as the moisture content increased. The ratio of V-max to K-m was the highest at 10% moisture content. The CH4 oxidation rate increased as the incubation temperature increased, and Q values and optimum temperature were determined to be 2.57-2.69 and 30 degrees C, respectively. Both V-max and K-m values decreased at the temperatures below and above 30 degrees C. The addition of various levels of NH4+ resulted in increased or decreased CH, oxidation rates, however, the initiation of appreciable CH, oxidation was delayed with increasing amounts of NH4+ application in all samples tested. Among the environmental variables tested, moisture content control seems to be the most important and an efficient means of managing methane oxidation when sandy soils are used in landfill cover.