Effects of CO2 leakage on soil bacterial communities from simulated CO2-EOR areas

Abstract

CO₂-EOR (enhanced oil recovery) has been proposed as a viable option for flooding oil and reducing anthropogenic CO₂ contribution to the atmospheric pool. However, the potential risk of CO₂ leakage from the process poses a threat to the ecological system. High-throughput sequencing was used to investigate the effects of CO₂ emission on the composition and structure of soil bacterial communities. The diversity of bacterial communities notably decreased with increasing CO₂ flux. The composition of bacterial communities varied along the CO₂ flux, with increasing CO₂ flux accompanied by increases in the relative abundance of Bacteroidetes and Firmicutes phyla, but decreases in the relative abundance of Acidobacteria and Chloroflexi phyla. Within the Firmicutes phylum, the genus Lactobacillus increased sharply when the CO₂ flux was at its highest point. Alpha and beta diversity analysis revealed that differences in bacterial communities were best explained by CO₂ flux. The redundancy analysis (RDA) revealed that differences in bacterial communities were best explained by soil pH values which related to CO₂ flux. These results could be useful for evaluating the risk of potential CO₂ leakages on the ecosystems associated with CO₂-EOR processes.