Yao Su
Mary-Cathrine Leewis
Yi-Xuan Chu
Jing Wang
Ruo-Chan Ma
Donglei Wu
Liang-Tong Zhan
Ian Charold Herriott
Mary Beth Leigh
Ruo He
2020
<p><span>CH</span><sub>4</sub><span> oxidation in landfill cover soils plays a significant role in mitigating CH</span><sub>4</sub><span> release to the atmosphere. Oxygen availability and the presence of co-contaminants are potentially important factors affecting CH</span><sub>4</sub><span> oxidation rate and the fate of CH</span><sub>4</sub><span>-derived carbon. In this study, microbial populations that oxidize CH</span><sub>4</sub><span> and the subsequent conversion of CH</span><sub>4</sub><span>-derived carbon into CO</span><sub>2</sub><span>, soil organic C and biomass C were investigated in landfill cover soils at two O</span><sub>2</sub><span> tensions, i.e., O</span><sub>2</sub><span> concentrations of 21% (“sufficient”) and 2.5% (“limited”) with and without toluene. CH</span><sub>4</sub><span>-derived carbon was primarily converted into CO</span><sub>2</sub><span> and soil organic C in the landfill cover soils, accounting for more than 80% of CH</span><sub>4</sub><span> oxidized. Under the O</span><sub>2</sub><span>-sufficient condition, 52.9%–59.6% of CH</span><sub>4</sub><span>-derived carbon was converted into CO</span><sub>2</sub><span> (CE</span><sub>CO2-C</sub><span>), and 29.1%–39.3% was converted into soil organic C (CE</span><sub>organic-C</sub><span>). A higher CE</span><sub>organic-C</sub><span> and lower CE</span><sub>CO2-C</sub><span> occurred in the O</span><sub>2</sub><span>-limited environment, relative to the O</span><sub>2</sub><span>-sufficient condition. With the addition of toluene, the carbon conversion efficiency of CH</span><sub>4</sub><span> into biomass C and organic C increased slightly, especially in the O</span><sub>2</sub><span>-limited environment. A more complex microbial network was involved in CH</span><sub>4</sub><span> assimilation in the O</span><sub>2</sub><span>-limited environment than under the O</span><sub>2</sub><span>-sufficient condition. DNA-based stable isotope probing of the community with </span><sup>13</sup><span>CH</span><sub>4</sub><span> revealed that </span><i>Methylocaldum</i><span> and </span><i>Methylosarcina</i><span> had a higher relative growth rate than other type I methanotrophs in the landfill cover soils, especially at the low O</span><sub>2</sub><span> concentration, while </span><i>Methylosinus</i><span> was more abundant in the treatment with both the high O</span><sub>2</sub><span> concentration and toluene. These results indicated that O</span><sub>2</sub><span>-limited environments could prompt more CH</span><sub>4</sub><span>-derived carbon to be deposited into soils in the form of biomass C and organic C, thereby enhancing the contribution of CH</span><sub>4</sub><span>-derived carbon to soil community biomass and functionality of landfill cover soils (i.e. reduction of CO</span><sub>2</sub><span> emission).</span></p>
application/pdf
10.1016/j.envpol.2019.113676
en
Elsevier
Low O2 level enhances CH4-derived carbon flow into microbial communities in landfill cover soils
article