Real-time monitoring of methane oxidation in a simulated landfill cover soil and MiSeq pyrosequencing analysis of the related bacterial community structure

Abstract

Real-time CH4 oxidation in a landfill cover soil was studied using automated gas sampling that determined biogas (CH4 and CO2) and O2 concentrations at various depths in a simulated landfill cover soil (SLCS) column reactor. The real-time monitoring system obtained more than 10,000 biogas (CH4 and CO2) and O2 data points covering 32 steady states of CH4 oxidation with 32 different CH4 fluxes (0.2–125mol·m−2·d−1). The kinetics of CH4 oxidation at different depths (0–20cm, 20–40cm, and 40–60cm) of SLCS were well fit by a CH4-O2 dual-substrate model based on 32 values (averaged, n=5–15) of equilibrated CH4 concentrations. The quality of the fit (R2 ranged from 0.90 to 0.96) was higher than those reported in previous studies, which suggests that real time monitoring is beneficial for CH4 oxidation simulations. MiSeq pyrosequencing indicated that CH4 flux events changed the bacterial community structure (e.g., increased the abundance of Bacteroidetes and Methanotrophs) and resulted in a relative increase in the amount of type I methanotrophs (Methylobacter and Methylococcales) and a decrease in the amount of type II methanotrophs (Methylocystis).