Abstract

The deep terrestrial biosphere encompasses the life belowthe photosynthesisfueled surface that perseveres in typically nutrient and energy depleted anoxic groundwaters. The composition and cycling of this vast dissolved organic matter (DOM) reservoir relevant to the global carbon cycle remains to be deciphered. Here we show that recent Baltic Sea-influenced to ancient preHolocene saline Fennoscandian Shield deep bedrock fracture waters carried DOM with a strong terrigenous signature and varying contributions from abiotic and biotic processes. Removal of easily degraded carbon at the surfaceto-groundwater transition and corresponding microbial community assembly processes likely resulted in the highly similar DOM signatures across the notably different water types that selected for a core microbiome. In combination with the aliphatic character, depleted d13C signatures in DOM indicated recent microbial production in the oldest, saline groundwater. Our study revealed the persistence of terrestrially-sourced carbon in severely energy limited deep continental groundwaters supporting deep microbial life.

Published in

Nature Communications
2022, Volume: 13, number: 1, article number: 4837
Publisher: NATURE PORTFOLIO

SLU Authors

• Turner, Stephanie

  • Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences
    
  • Linnaeus University

UKÄ Subject classification

Ecology
Geochemistry


Publication identifier

DOI: https://doi.org/10.1038/s41467-022-32457-z

Permanent link to this page (URI)

https://res.slu.se/id/publ/123012