Geological sources of H and abiotic CH have had a critical role in the evolution of our planet and the development of life and sustainability of the deep subsurface biosphere. Yet the origins of these sources are largely unconstrained. Hydration of mantle rocks, or serpentinization, is widely recognized to produce H and favour the abiotic genesis of CH in shallow settings. However, deeper sources of H and abiotic CH are missing from current models, which mainly invoke more oxidized fluids at convergent margins. Here we combine data from exhumed subduction zone high-pressure rocks and thermodynamic modelling to show that deep serpentinization (40-80 km) generates significant amounts of H and abiotic CH, as well as HS and NH. Our results suggest that subduction, worldwide, hosts large sources of deep H and abiotic CH, potentially providing energy to the overlying subsurface biosphere in the forearc regions of convergent margins.
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http://dx.doi.org/10.1038/s41467-020-17342-x | DOI Listing |
Front Microbiol
December 2024
Department of Earth Sciences, University of Southern California, Los Angeles, CA, United States.
Microbial activity in the deep continental subsurface is difficult to measure due to low cell densities, low energy fluxes, cryptic elemental cycles and enigmatic metabolisms. Nonetheless, direct access to rare sample sites and sensitive laboratory measurements can be used to better understand the variables that govern microbial life underground. In this study, we sampled fluids from six boreholes at depths ranging from 244 m to 1,478 m below ground at the Sanford Underground Research Facility (SURF), a former goldmine in South Dakota, United States.
View Article and Find Full Text PDFMicrob Ecol
December 2024
Department of Biology, New Mexico Institute of Mining and Technology, Socorro, NM, 87801, USA.
Viruses are the most abundant biological entities on Earth, and they play a critical role in the environment and biosphere where they regulate microbial populations and contribute to nutrient cycling. Environmental viruses have been the most studied in the ocean, but viral investigations have now spread to other environments. Here, viral communities were characterized in four cave pools in Carlsbad Caverns National Park to test the hypotheses that (i) viral abundance is ten-fold higher than prokaryotic cell abundance in cavern pools, (ii) cavern pools contain novel viral sequences, and (iii) viral communities in pools from developed portions of the cave are distinct from those of pools in undeveloped parts of the same cave.
View Article and Find Full Text PDFEnviron Microbiome
December 2024
GFZ German Research Centre for Geosciences, Section Geomicrobiology, Potsdam, Germany.
The Eger Rift subsurface is characterized by frequent seismic activity and consistently high CO concentrations, making it a unique deep biosphere ecosystem and a suitable site to study the interactions between volcanism, tectonics, and microbiological activity. Pulses of geogenic H during earthquakes may provide substrates for methanogenic and chemolithoautotrophic processes, but very little is currently known about the role of subsurface microorganisms and their cellular processes in this type of environment. To assess the impact of geologic activity on microbial life, we analyzed the geological, geochemical, and microbiological composition of rock and sediment samples from a 238 m deep drill core, running across six lithostratigraphic zones.
View Article and Find Full Text PDFEnviron Microbiome
December 2024
Innovative Genomics Institute, University of California, Berkeley, CA, 94720, USA.
Background: Underground research laboratories (URLs) provide a window on the deep biosphere and enable investigation of potential microbial impacts on nuclear waste, CO and H stored in the subsurface. We carried out the first multi-year study of groundwater microbiomes sampled from defined intervals between 140 and 400 m below the surface of the Horonobe and Mizunami URLs, Japan.
Results: We reconstructed draft genomes for > 90% of all organisms detected over a four year period.
Sci Adv
December 2024
College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA.
Subsurface environments are among Earth's largest habitats for microbial life. Yet, until recently, we lacked adequate data to accurately differentiate between globally distributed marine and terrestrial surface and subsurface microbiomes. Here, we analyzed 478 archaeal and 964 bacterial metabarcoding datasets and 147 metagenomes from diverse and widely distributed environments.
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