Solute Production and Transport Processes in Chinese Monsoonal Rivers: Implications for Global Climate Change

The negative feedback between chemical weathering and climate is hypothesized to act as an important control on modulating atmospheric CO2 over geologic timescales, affecting the evolution of Earth's climate over the history of Earth. Here, we investigated solute production processes by analyzing concentration‐discharge, denoted here as concentration‐runoff (C‐q), relationships of Chinese monsoonal rivers, through both the empirical power law relationship and a recently developed Solute Production Model. We found that solute concentrations were highly modulated by hydrologic conditions which shifted the Damköhler number, Da, the ratio of fluid transit time versus the time required to reach equilibrium. Additionally, the among‐catchment behavior of HCO3− responding to changing runoff was correlated with the average Da of each catchment. Rivers with high average Da induced high maximum weathering fluxes, while the maximum weathering potential was primarily controlled by the Damköhler coefficient (Dw, m/yr), the reactivity of the material in the weathering zone over a given length scale, among the catchments in this study. Globally, HCO3− behaviors and weathering characteristics are highly influenced by carbonate bedrock distributions and abundance. In addition, Chinese monsoonal rivers have higher weathering fluxes, weathering potential, and climate‐weathering feedback sensitivity (4.4%/°C) than most other global rivers. Our work disclosed the mechanisms that link runoff, lithology, and weathering fluxes in monsoonal rivers and analyzed the controlling factors on solute dynamics on global scale, which can be implemented in exploring the chemical weathering processes under ongoing global climate change. Plain Language Summary Continental weathering controls many aspects of the surface‐Earth system, including imposing negative feedback on long‐term carbon cycle. In this study, empirical power law relationship and process‐based Solute Production Model (SPM) were used to disclose solute production and transport processes based on temporal sampling and analyses from Chinese monsoonal rivers. We found that high dissolution rates and high reactive surface areas led to solute concentrations that were relatively invariant with changing runoff. Additionally, the among‐catchment behavior of HCO3− responding to changing runoff was correlated with the average ratio of fluid transit time versus the time required to reach equilibrium of each catchment. Globally, the areal