Tropical cyclones likely enhance chemical weathering but suppress atmospheric CO2 consumption in landslide-dominated catchments

The coupling between chemical weathering (including silicate, carbonate and pyrite weathering) and physical erosion is of high interest in active mountain belts. Participation of pyrite weathering which, results in CO2 emission to the atmosphere, also is of great research attention. Nevertheless, the responses of the (de-)couplings to landslide and typhoon are unclear. We used records of riverine TDS (total dissolved solids) and TSS (total suspended solids) with high-frequency sampling during typhoons to estimate chemical denudation rates of silicate (CDRsil), carbonate (CDRcarb), pyrite (CDRpyrite) and physical denudation rates (PDR) in two adjacent catchments, eastern Taiwan. Results show that the CDRsil in the two catchments is approx. 10-fold higher than the global mean, whereas the CDRcarb, CDRpyrite and PDR are over 15-fold higher than the global averages. Landslides likely elevate carbonate and sulfate dissolution, and streamflow is a kinetic control on the CDRs. Among CDRs, CDRsil remains constant with various landslides and typhoons. Yet, CDRcarb and CDRpyrite rapidly respond to typhoons and then contribute more CO2 emission. In sum, landslides expose fresh minerals to enhance chemical weathering; typhoons, which transport the dissolved solids within a short time and prompt new rainwater for weathering, are also dominant agents. We demonstrate the importance of dynamic partitioning of sulfuric and carbonic acid on silicate weathering for quantitative estimation of weathering-associated CO2 budget in active mountain belts.

Automated summary

The coupling between chemical weathering and physical erosion in active mountain belts, particularly the impact of landslides and typhoons on this coupling, is of significant interest. Landslides enhance chemical weathering by exposing fresh minerals, while typhoons prompt rapid responses in carbonate and pyrite weathering rates, contributing to increased CO2 emissions.