Relationships between microbial communities and groundwater chemistry in two pristine confined groundwater aquifers in central China

Abstract

This study explores linkages between the microbial composition and hydrochemical variables of pristine groundwater to identify active redox conditions and processes. Two confined aquifers underlying the city of Qianjiang in the Jianghan Plain in China were selected for this study, having different recharge sources and strong hydrochemical gradients. Typical methods for establishing redox processes according to threshold concentration criteria for geochemical parameters suggest iron or sulphate reduction processes. High‐throughput 16S rRNA sequencing was used to obtain diversity and taxonomic information on microbial communities. Instead of revealing iron‐ and sulphate‐reducing bacteria, salt‐ and alkali‐tolerant bacteria, such as the phylum Firmicutes and the class Gammaproteobacteria, and in particular, the family Bacillaceae, were dominant in the downstream groundwater of the first aquifer that had high ion concentrations caused by the dissolution of calcite and dolomite; meanwhile, the heterotrophic microaerophilic families Comamonadaceae and Rhodocyclaceae prevailed in the upstream groundwater of the first aquifer. Sulphate‐reducing bacteria were extremely abundant in the upstream groundwater of the second aquifer, as the SO42− concentration was especially high. Methanogens and methanotrophs were predominant in the downstream groundwater of the second aquifer even though the concentration of SO42− was much higher than 0.5 mg L−1. The microbial communities, together with the geochemical parameters, indicated that the upstream region of the first aquifer was suboxic, that Fe(III) and Mn(IV) reductions were not the main redox processes in the downstream groundwater of the first aquifer with high Fe and Mn concentrations, and that the redox processes in the upstream and downstream regions of the second confined aquifer were SO42− reduction and methanogenesis, respectively. This study expands understanding of the linkages between microbial communities and hydrogeochemistry in pristine groundwaters and provides more evidence for identifying active redox conditions and processes.

Assessment of the in situ biomethanation potential of a deep aquifer used for natural gas storage

“…5 B ). These archaeal families are regularly highlighted in microbial communities in deep aquifers (Kotelnikova et al 1998 , Ma et al 2019 , Kadnikov at et al 2020 , Ranchou-Peyruse et al 2019 , 2021 , Moliková et al 2022 ) and were assumed to be responsible for in situ biomethanation in the case of town gas storage at the Lobodice site (Czechia; Buzek et al 1994 , Moliková et al 2022 ). The growth conditions interfered with the representativeness of ASVs but ultimately had little influence on the results at the genus level.…”

Comparative Study of Microbial Diversity in Different Coastal Aquifers: Determining Factors

“…In cases such as this, only the soil microbiota can have any influence when there is a connection with the aquifer [44]. In pristine aquifers, the influence of geochemical characteristics on the shaping of the microbial community is greater than in contaminated environments [74][75][76]. In the latter, the identity and relative abundance of microbial species is affected by the presence of compounds of anthropogenic origin [77].…”

Carbon and Sulfur Isotope Methods for Tracing Groundwater Contamination: A Review of Sustainable Utilization in Reclaimed Municipal Landfill Areas

“…However, this only applies to exceptional situations, and on-site remedial measures are usually carried out. One literature review showed that the formation of leachates and their migration in an aquifer, despite the reclamation of old landfills, were serious problems observed in many countries (e.g., the United States of America, China, Italy, and Poland, e.g., [10][11][12][13][14][15]). Despite reclamation, the processes occurring in the stored waste, depending on many complex factors (moisture, temperature, redox conditions, pH, and types of microorganisms), lead to the formation of leachates and biogas, which affect the surrounding environment for a long time [16].…”