Abstract
Alluvial aquifers can provide ecosystem services and drinking water but much remains unknown about human effects on aquifer microbiomes. Therefore, we used amplicon sequencing and hydro chemical characterization to pair microbial communities with environmental conditions across 37 alluvial aquifer wells. The study region spanned eastern Iowa and southern Minnesota (USA) and contained a combination of drinking water and monitoring wells. In terms of microbial ecology, dominant phyla across the wells included Proteobacteria, Bacteroidota, Patescibacteria, Planctomycetota, and Nitrospirota. Tritium, an indicator of infiltration and surface water influence, was the highest correlated variable with the Shannon index (α-diversity) by the Spearman rank sum (ρ = 0.60) and one of only four significant environmental variables in the constrained correspondence analysis. We built random forest regression models to predict tritium concentrations from microbial family relative abundance (held-out testing coefficient of determination (R2) = 0.77 and mean absolute percentage error = 7%) and interpreted the models with Shapley additive explanation values. The most important families for predicting tritium concentrations were Nitrosopumilaceae and Methylomirabilaceae. Upwelling methane could contribute to the unusual coupling of ammonia oxidation by Nitrosopumilaceae with simultaneous nitrite-dependent methane oxidation by Methylomirabilaceae. Taken together, we illuminate the relationship among hydrochemistry, hydraulic connectivity, and alluvial aquifer microbiomes.
Recommended Citation
H. W. Schroer et al., "Hydraulic Connectivity And Hydrochemistry Influence Microbial Community Structure In Agriculturally Affected Alluvial Aquifers In The Midwestern United States," Environmental Science and Technology, American Chemical Society, Jan 2025.
The definitive version is available at https://doi.org/10.1021/acs.est.5c03155
Department(s)
Civil, Architectural and Environmental Engineering
Publication Status
Open Access
Keywords and Phrases
biogeochemistry; denitrification; groundwater; microbiomes; N-DAMO; nitrification; tritium
International Standard Serial Number (ISSN)
1520-5851; 0013-936X
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2025 American Chemical Society, All rights reserved.
Publication Date
01 Jan 2025
