Resilience of deep aquifer microbial communities to seasonal hydrological fluctuations

• 成果类型: Article
• 署名作者: Giroud, Sebastien; Deng, Longhui; Lever, Mark A.; Schilling, Oliver S.; Kipfer, Rolf
• 署名单位: Swiss Federal Institutes of Technology Domain; Swiss Federal Institute of Aquatic Science & Technology (EAWAG); Swiss Federal Institutes of Technology Domain; ETH Zurich; Shanghai Jiao Tong University; University of Texas System; University of Texas Austin; University of Basel; Swiss Federal Institutes of Technology Domain; ETH Zurich
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-8467
• DOI: 10.1073/pnas.2422608122
• 发表日期: 2025-06-10
• 关键词: mass-spectrometric system; ground-water; gen. nov.; archaea; carbon; diversity; sediment; insights; proposal; oxygen

摘要

The influence of seasonal variations in temperature and precipitation on subsurface biogeochemical processes remains poorly understood. In the Lavey-les-Bains thermal system in the Swiss Alps, annual variations in electrical conductivity are observed to depths of 500 m, suggesting a potential link to surface environmental changes. Here we show, through year-round analyses of stable water isotopes, noble gases, and conductivity, that seasonally varying contributions of shallow groundwater from the Rh & ocirc;ne alluvial aquifer mix with deep groundwater. Despite vertically similar fluid geochemical compositions suggesting high hydrological connectivity, microbial communities exhibit significant depth-dependent variation with minimal seasonal change. This decoupling of dynamic water source partitioning and stable microbial community structure has not been previously observed and fills a critical gap in our understanding of geothermal systems and microbial life in the deep subsurface. At 200 m, the communities are dominated by sulfur-disproportionating Bacteria (Dissulfurispira) and Micrarchaeota, while at 500 m the major groups include sulfate-and iron-reducers and/or hydrogen-oxidizers (Thermales, Thermodesulfobacteriota, and Bathyarchaeota). Our study highlights the resilience of terrestrial subsurface microbial communities to temporal variations in water sources and fluid composition. We propose that intrinsic environmental properties-such as temperature-are more critical drivers of microbial community structure in hydrologically connected deep aquifers than seasonal hydrological changes.