Abstract

High-elevation mountains have experienced disproportionately rapid warming, yet the effect of warming on the lateral export of terrestrial carbon to rivers remains poorly explored and understood in these regions. Here, we present a long-term data set of dissolved inorganic carbon (DIC) and a more detailed, short-term data set of DIC, delta C-13(DIC), and organic carbon from two major rivers of the Qinghai-Tibetan Plateau, the Jinsha River (JSR) and the Yalong River (YLR). In the higher-elevation JSR with similar to 51% continuous permafrost coverage, warming (>3 degrees C) and increasing precipitation coincided with substantially increased DIC concentrations by 35% and fluxes by 110%. In the lower-elevation YLR with similar to 14% continuous permafrost, such increases did not occur despite a comparable extent of warming. Riverine concentrations of dissolved and particulate organic carbon increased with discharge (mobilization) in both rivers. In the JSR, DIC concentrations transitioned from dilution (decreasing concentration with discharge) in earlier, colder years to chemostasis (relatively constant concentration) in later, warmer years. This changing pattern, together with lighter delta C-13(DIC) under high discharge, suggests that permafrost thawing boosts DIC production and export via enhancing soil respiration and weathering. These findings reveal the predominant role of warming in altering carbon lateral export by escalating concentrations and fluxes and modifying export patterns.

Keywords

carbon cycle; carbon isotope; concentration-dischargerelationship; climate change; Qinghai-TibetPlateau

Published in

Environmental Science and Technology
2024, Volume: 58, number: 16, pages: 7032 - 7044
Publisher: AMER CHEMICAL SOC

SLU Authors

• Klaus, Marcus

  • Department of Forest Ecology and Management, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Physical Geography
Environmental Sciences


Publication identifier

DOI: https://doi.org/10.1021/acs.est.3c06777

Permanent link to this page (URI)

https://res.slu.se/id/publ/129350