Investigating the Groundwater Microbiome in Sulfate-Rich Aquifers of the Reynolds Creek Critical Zone Observatory, Southwestern Idaho
Faculty Mentor Information
Anirban Chakraborty, Idaho State University
Kathleen Lohse, Idaho State University
Presentation Date
7-2025
Abstract
In the Earth’s subsurface life is comprised exclusively of microorganisms, and estimates indicate that approximately 12-20% of the global prokaryotic biomass is found in the continental subsurface. In this realm, groundwater systems serve as prominent microbial habitats, hosting non-photosynthetic chemotrophic microbial communities. Sulfate-reducing microorganisms are common in Earth's subsurface, often using hydrogen derived directly from radiolysis of pore water and sulfate derived from oxidation of rock-matrix-hosted sulfides by radiolytically derived oxidants. During the summers of 2022 and 2023, we sampled groundwater from two adjacent wells within the Reynolds Creek Critical Zone Observatory in Southwestern Idaho including a newly dug nested well with surprisingly high sulfate concentrations, varying seasonally between 1000-2500 mg/L. Microbial diversity in the groundwater samples was investigated using high throughput 16S ribosomal RNA gene amplicon sequencing conducted at Idaho State University’s Molecular Research Core Facility. Microbial communities in the sulfate-rich waters were observed to be dominated by known sulfate-reducing bacterial genera e.g. Desulfosporosinus. Beta diversity analysis further demonstrated that the microbial communities in the sulfate-rich aquifer were significantly different from those in the adjacent well with low sulfate concentrations. These results provide initial evidence of microbially-mediated sulfur cycling within sulfate-rich aquifers in the Reynolds Creek watershed.
Investigating the Groundwater Microbiome in Sulfate-Rich Aquifers of the Reynolds Creek Critical Zone Observatory, Southwestern Idaho
In the Earth’s subsurface life is comprised exclusively of microorganisms, and estimates indicate that approximately 12-20% of the global prokaryotic biomass is found in the continental subsurface. In this realm, groundwater systems serve as prominent microbial habitats, hosting non-photosynthetic chemotrophic microbial communities. Sulfate-reducing microorganisms are common in Earth's subsurface, often using hydrogen derived directly from radiolysis of pore water and sulfate derived from oxidation of rock-matrix-hosted sulfides by radiolytically derived oxidants. During the summers of 2022 and 2023, we sampled groundwater from two adjacent wells within the Reynolds Creek Critical Zone Observatory in Southwestern Idaho including a newly dug nested well with surprisingly high sulfate concentrations, varying seasonally between 1000-2500 mg/L. Microbial diversity in the groundwater samples was investigated using high throughput 16S ribosomal RNA gene amplicon sequencing conducted at Idaho State University’s Molecular Research Core Facility. Microbial communities in the sulfate-rich waters were observed to be dominated by known sulfate-reducing bacterial genera e.g. Desulfosporosinus. Beta diversity analysis further demonstrated that the microbial communities in the sulfate-rich aquifer were significantly different from those in the adjacent well with low sulfate concentrations. These results provide initial evidence of microbially-mediated sulfur cycling within sulfate-rich aquifers in the Reynolds Creek watershed.