Klaus, Marcus
- Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
Abstract
Global climate is modulated by the balance between CO2 release from coupled sulfide-carbonate weathering and CO2 sequestration through silicate weathering, yet how this balance evolves under climate change remains poorly constrained. Here we investigate the temporal variability in dissolved chemistry and isotopic ratios from two major rivers on the Tibetan Plateau, the Jinsha River and the Yalong River, over two periods within a nineyear span (2013-2014 and 2018-2021). In the evaporite-rich, permafrost-dominated Jinsha River basin, we detected exceptional increases in evaporite-derived elemental concentrations and fluxes, both interannually and during the monsoon season, compared with other mineral sources. These shifts reflect enhanced evaporite exposure driven by warming-induced thermal processes such as permafrost thaw, altered subsurface flow paths, and enhanced hydrologic connectivity between saline lakes and rivers. By contrast, weathering fluxes in the evaporite-poor Yalong River basin exhibit relatively small temporal changes. Sulfide oxidation offsets all silicate weathering-driven alkalinity in the Jinsha River basin and 40-98% in the Yalong River basin, with the offset intensifying during monsoon-driven permafrost-thaw-and high-flow periods. Concurrently, accelerated gypsum/ anhydrite weathering could prompt CO2 release from soils and streams by inducing secondary carbonate precipitation. Interannually, the growing dominance of sulfide oxidation also shifts the CO2 balance toward net CO2 release. These processes demonstrate that mineral weathering associated with permafrost thaw can strengthen CO2 sources to the atmosphere and amplify the permafrost carbon-climate feedback. Overall, global warming and the associated acceleration of the hydrologic cycle could result in CO2 release rather than drawdown from rock weathering in permafrost landscapes underlain by sulfide-and evaporite-rich lithologies.
Keywords
Chemical weathering; Carbon cycle; Climate warming; Permafrost thawing; Tibetan Plateau
Published in
Geochimica et Cosmochimica Acta
2025, volume: 407, pages: 174-192
Publisher: PERGAMON-ELSEVIER SCIENCE LTD
SLU Authors
UKÄ Subject classification
Geochemistry
Publication identifier
- DOI: https://doi.org/10.1016/j.gca.2025.09.006
Permanent link to this page (URI)
https://res.slu.se/id/publ/143822