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

摘要

Real-time CH_4 oxidation in a landfill cover soil was studied using automated gas sampling that determined biogas (CH_4 and CO_2) and O_2 concentrations at various depths in a simulated landfill cover soil (SLCS) column reactor. The real-time monitoring system obtained more than 10,000 biogas (CH_4 and CO_2) and O_2 data points covering 32 steady states of CH_4 oxidation with 32 different CH_4 fluxes (0.2-125 mol·m~(-2)·d~(-1)). The kinetics of CH_4 oxidation at different depths (0-20 cm, 20-40 cm, and 40-60 cm) of SLCS were well fit by a CH_4-O_2 dual-substrate model based on 32 values (averaged, n = 5-15) of equilibrated CH_4 concentrations. The quality of the fit (R~2 ranged from 0.90 to 0.96) was higher than those reported in previous studies, which suggests that real time monitoring is beneficial for CH_4 oxidation simulations. MiSeq pyrosequencing indicated that CH_4 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).