Biogeochemical sulfur cycling in sulfidic karst systems is largely driven by abiotic and biological sulfide oxidation, but the fate of elemental sulfur (S0) that accumulates in these systems is not well understood. The Frasassi Cave system (Italy) is intersected by a sulfidic aquifer that mixes with small quantities of oxygen‐rich meteoric water, creating Proterozoic‐like conditions and supporting a prolific ecosystem driven by sulfur‐based chemolithoautotrophy. To better understand the cycling of S0in this environment, we examined the geochemistry and microbiology of sediments underlying widespread sulfide‐oxidizing mats dominated by
Permafrost degradation is altering biogeochemical processes throughout the Arctic. Thaw‐induced changes in organic matter transformations and mineral weathering reactions are impacting fluxes of inorganic carbon (IC) and alkalinity (ALK) in Arctic rivers. However, the net impact of these changing fluxes on the concentration of carbon dioxide in the atmosphere (
- Award ID(s):
- 2127442
- NSF-PAR ID:
- 10476303
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Global Biogeochemical Cycles
- Volume:
- 37
- Issue:
- 11
- ISSN:
- 0886-6236
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Beggiatoa . Sediment populations were dominated by uncultivated relatives of sulfur cycling chemolithoautotrophs related toSulfurovum ,Halothiobacillus ,Thiofaba ,Thiovirga ,Thiobacillus , andDesulfocapsa , as well as diverse uncultivated anaerobic heterotrophs affiliated withBacteroidota , Anaerolineaceae, Lentimicrobiaceae, and Prolixibacteraceae.Desulfocapsa andSulfurovum populations accounted for 12%–26% of sediment 16S rRNA amplicon sequences and were closely related to isolates which carry out autotrophic S0disproportionation in pure culture. Gibbs energy (∆G r ) calculations revealed that S0disproportionation under in situ conditions is energy yielding. Microsensor profiles through the mat‐sediment interface showed thatBeggiatoa mats consume dissolved sulfide and oxygen, but a net increase in acidity was only observed in the sediments below. Together, these findings suggest that disproportionation is an important sink for S0generated by microbial sulfide oxidation in this oxygen‐limited system and may contribute to the weathering of carbonate rocks and sediments in sulfur‐rich environments. -
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