Hotspots of riverine greenhouse gas (CH4, CO2, N2O) emissions from Qinghai Lake Basin on the northeast Tibetan Plateau.

Abstract

Evasion of greenhouse gases (GHG) from fluvial systems is now recognized as a significant component of the global carbon cycle. However, the magnitudes of GHG fluxes remain uncertain due to limited research data, especially on the Tibetan Plateau. In this study Methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O) concentrations were measured and their diffusive fluxes were estimated by headspace-gas chromatography in two rivers basins (Buha and Shaliu rivers) on the Northeast Tibetan Plateau during three seasons from October 2020 to August 2021. The results showed that the focal rivers on the Tibetan Plateau are potentially important sources of GHG. Both rivers have higher GHG concentrations and diffusion flux during the snowmelt period than other seasons. In general, GHG diffusion fluxes in the Buha river were higher than those in the Shaliu river and their concentrations are higher in the upstream region than in the downstream region of both basins. The salinity in water and wind spread were found to be important factors influencing in GHGs diffusion fluxes. While diffusive fluxes of GHG in rivers were a small component of watershed-scale fluvial Carbon gas efflux compared to other studies, these fluxes will likely increase as thaw slump occurrence. Overall, this study highlights that better recognition of the influence that river networks have on global warming is required-especially when it comes to high-elevation rivers across permafrost, as permafrost will continue to thaw as climate warming.