Influence of CO2 on Water Chemistry and Bacterial Community Structure and Diversity: An Experimental Study in the Laboratory

Abstract

As the second largest carbon pool, soil has a high CO2 content, and it has an important impact on water–rock interactions and the bacterial community structure and diversity in soils. In this paper, three sets of laboratory simulation experiments under six levels of partial pressure CO2 (pCO2) conditions were used to analyze and study the CO2–water–rock interactions and the bacterial community structure and diversity changes in soil under normal temperature and pressure. Results (1) The change of pCO2 had an obvious influence on the chemical components. The dissolution of CO2 led to the dissolution of dolomite and calcite, which increased the concentrations of HCO3−, Ca2+, and Mg2+ significantly. (2) The influence of pCO2 on the bacterial community structure and diversity was different, and the bacterial community structure became more complex and diverse with the extension of the experiment time. In the experiments, Proteobacteria and Firmicutes were the main dominant phyla, and Gammaproteobacteria and Bacilli were the main dominant classes. The abundance of Bacteroidetes and Bacteroidia was significantly increased with the increasing pCO2. (3) pH had a significant influence on the bacterial community structure during the experiments, and the influences of different chemical components, such as HCO3−, Ca2+, Mg2+, total dissolved solids (TDS), and K+, on the abundance of different bacterial species were significantly different. This work can provide a theoretical basis for the technology of bacterial–geological storage of CO2, and it has important significance for the protection of the groundwater environment and the soil ecosystem.