标题：Impacts of NO<sub>2</sub> Impurities on the Indigenous Microbial Community Structure and Diversity in CO<sub>2</sub>-Saline-Sandstone Interaction System
摘要：Laboratory experiments (150 days) were performed to analyze the influence of NO<sub>2</sub> impurities on indigenous microbial communities and diversity with 16S rRNA sequence at real GCS site (Geological CO<sub>2</sub> Sequestration, ordos, China) conditions (pressure: 15 MPa, temperature: 55 °C). The possible impact of metabolic activity on the GCS process was investigated through the BLASTn search. Compared with the pure CO<sub>2</sub>, results demonstrate that the biomass and biodiversity were lower, due to the lower pH, within 60 days after the co-injection of 0.1% NO<sub>2</sub>. Subsequently, the pH was quickly buffered through the corrosion of feldspar and clay, and the impact of NO<sub>2</sub> had almost no obvious effect on the microbial structure except the abundance of phylum and genus after 90 days. In addition, acid-producing bacteria appeared after 60 days, such as <i>Bacillus</i>, <i>Acinetobacter,</i> and <i>Lactococcus</i>, etc., lower the pH in the solution and accelerate the dissolution of minerals. The Fe (III)-reducing microbes <i>Citrobacter freundii</i> reduce the Fe (III) released from minerals to Fe (II) and induce siderite (FeCO<sub>3</sub>) biomineralization through biogeochemical processes. Therefore, the co-injection of trace NO<sub>2</sub> will not significantly affect the growth of microorganisms on long timescale.
