Impacts of NO2 Impurities on the Indigenous Microbial Community Structure and Diversity in CO2-Saline-Sandstone Interaction System

Chenyang Li,Yunpeng Song,Qingwei Meng,Yongjuan Zhu,Ying Lyu

doi:10.3390/su13115916

Abstract

Laboratory experiments (150 days) were performed to analyze the influence of NO2 impurities on indigenous microbial communities and diversity with 16S rRNA sequence at real GCS site (Geological CO2 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 CO2, results demonstrate that the biomass and biodiversity were lower, due to the lower pH, within 60 days after the co-injection of 0.1% NO2. Subsequently, the pH was quickly buffered through the corrosion of feldspar and clay, and the impact of NO2 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 Bacillus, Acinetobacter, and Lactococcus, etc., lower the pH in the solution and accelerate the dissolution of minerals. The Fe (III)-reducing microbes Citrobacter freundii reduce the Fe (III) released from minerals to Fe (II) and induce siderite (FeCO3) biomineralization through biogeochemical processes. Therefore, the co-injection of trace NO2 will not significantly affect the growth of microorganisms on long timescale.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
With the 16S rRNA sequence and qPCR analysis, a lower pH was achieved resulting in lower biomass and biodiversity than the pure CO2 injection group within 90 days after 0.1% NO2 impurities was co-injected
With the rapid mineral dissolution, the pH gap between the NO2 impurities and pure CO2 groups was reduced over time, which means the impact of NO2 impurities on biomass and biodiversity gradually became weaker

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The burning of fossil fuels has substantially increased the levels of CO2 in the atmosphere from 228 ppm in the preindustrial age to the current level of 415.88 ppm, leading to significant climate changes across the globe [1]. Carbon capture and storage (CCS) technology is regarded as an effective way to reduce CO2 emission. It is mainly to capture and seal CO2 in natural or artificial “containers” to reduce emissions to the atmosphere, such as geological storage, biological storage, marine storage, mineral storage, and so on [2,3].

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