Chemical weathering in glacial catchment acting as a net carbon source

Over geological time scales, continental silicate weathering is considered as a critical carbon sink that regulates long-term climate feedback. By contrast, recent studies indicate that sulfide oxidation during weathering can be as a potential carbon source. However, whether chemical weathering in glacial conditions characterized by extreme erosion is a net carbon sink or source remains elusive. Here, we present the seasonal carbon cycle processes in a typical glacier catchment, via high-resolution (weekly) river water sampling during the whole 2017 in the Laohugou river, northeastern Tibetan Plateau. Our seasonal result shows that the release of CO₂ by sulfide oxidation during the monsoon period can be much faster than CO₂ consumption through weathering of silicate rocks, with maximum of ∼26 times. Extending to global glacial basins, we observed a consistent pattern that inorganic carbon releases in alpine glaciers are faster than atmospheric CO₂ consumption. We propose that weathering in global glacial environment acts as a significant carbon source, and thus affects climate feedback.