Dynamics of CH4 oxidation in landfill biocover soil: effect of O2/CH4 ratio on CH4 metabolism.

The CH(4) oxidation dynamics was investigated by observing the CH(4) oxidation rates at concentrations (from 1.0 × 10(4) ppmv to 2.0 × 10(5) ppmv) mixed with O(2) (from 5.0 × 10(4) ppmv to 7.5 × 10(5) ppmv). The CH(4)-O(2) dual-substrate model based on Michaelis-Menten equation (K(m, CH4) = 1.4 × 10(5) ppmv; V(max) = 7.6 × 10(2) μmol kg(-1) d(-1); K(m, O2) = 5.5 × 10(4) ppmv) was got and agreed well with the experimental data when the initial O(2)/CH(4) ratio reached 3:1, indicating full aerobic CH(4) oxidization. Anoxic CH(4) oxidation gradually became predominant with decreasing O(2)/CH(4) ratios. The effect of CH(4) is more significant than O(2), as evidenced by higher slope (0.58 kg(-1) d(-1)) of V(CH4) - [S(CH4)] line graph compared with that of V(CH4) - [S(CH4)] line graph (0.062 kg(-1) d(-1)). The paper presents the dynamics of CH(4) oxidation and proposes that ratio of O(2)/CH(4) need to be considered for their dynamically changing in environmental habitats. The findings provide an important parameter for optimizing the operations of breathing biocover systems.