We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Controls on the Respiration of Ancient Carbon Draining From Permafrost Soils Into Sunlit Arctic Surface Waters.
- Authors
Rieb, E. C.; Polik, C. A.; Ward, C. P.; Kling, G. W.; Cory, R. M.
- Abstract
The thawing of ancient organic carbon stored in arctic permafrost soils, and its oxidation to carbon dioxide (CO2, a greenhouse gas), is predicted to amplify global warming. However, the extent to which organic carbon in thawing permafrost soils will be released as CO2 is uncertain. A critical unknown is the extent to which dissolved organic carbon (DOC) from thawing permafrost soils is respired to CO2 by microbes upon export of freshly thawed DOC to both dark bottom waters and sunlit surface waters. In this study, we quantified the radiocarbon age and 13C composition of CO2 produced by microbial respiration of DOC that was leached from permafrost soils and either kept in the dark or exposed to ultraviolet and visible wavelengths of light. We show that permafrost DOC most labile to microbial respiration was as old or older (ages 4,000–11,000 a BP) and more 13C‐depleted than the bulk DOC in both dark and light‐exposed treatments, likely indicating respiration of old, 13C‐depleted lignin and lipid fractions of the permafrost DOC pool. Light exposure either increased, decreased, or had no effect on the magnitude of microbial respiration of old permafrost DOC relative to respiration in the dark, depending on both the extent of DOC oxidation during exposure to light and the wavelength of light. Together, these findings suggest that photochemical changes affecting the lability of permafrost DOC during sunlight exposure are an important control on the magnitude of microbial respiration of permafrost DOC in arctic surface waters. Plain Language Summary: Organic carbon has been frozen in arctic permafrost soils for thousands of years. As these soils warm and thaw, the vast stores of ancient organic carbon they contain can amplify global warming if the carbon is converted to carbon dioxide (a greenhouse gas) in both dark soils and when drained into sunlit lakes and streams. However, quantifying the carbon dioxide produced from thawed permafrost organic carbon requires understanding the controls on this conversion. Here we show that native permafrost microbes can respire permafrost organic carbon to carbon dioxide both in the dark and after carbon exposure to different wavelengths of light. The carbon dioxide produced was as old as the organic carbon in the soil, suggesting that even ancient carbon can be respired by microbes. This study suggests that respiration by microbes will contribute to the rapid conversion of ancient permafrost organic carbon to carbon dioxide in sunlit arctic surface waters, further amplifying global warming. Key Points: Microbes respire ancient, 13C‐depleted dissolved organic carbon (DOC) from permafrost soils to carbon dioxideEffects of sunlight exposure on the amount of permafrost DOC respired depend on the extent of DOC oxidation by each wavelength of lightSunlight exposure of permafrost DOC can increase or decrease microbial respiration in arctic lakes and streams
- Subjects
TUNDRAS; PERMAFROST; DISSOLVED organic matter; SOILS; MICROBIAL respiration; RESPIRATION
- Publication
Journal of Geophysical Research. Biogeosciences, 2024, Vol 129, Issue 5, p1
- ISSN
2169-8953
- Publication type
Article
- DOI
10.1029/2023JG007853