Patterns and controlling factors of rock weathering carbon sink in global major rivers.

Rock weathering actively participates in the global carbon cycle on both short and long-time scales. However, considerable debate on the global carbon sink flux, spatial patterns, and controlling factors of rock weathering still exists. In this study, we estimated the carbon sink flux of carbonate rocks (Fcarb) and silicate rocks (Fsil) weathering in global major rivers using hydrochemistry-discharge method and GEM-CO model based on the GEMS-GLORI Database, and analyzed the controlling factors affecting the rock weathering. The results show that the Fcarb and Fsil are 3.09 and 1.73 t km yr, respectively, and the total amount of weathering carbon sink of carbonate rocks (Tcarb) and silicate rocks (Tsil) are 0.17 and 0.093 Pg yr, respectively. The rock weathering carbon sink (RWCS) shows significant differences among different continents, latitudes, and climate zones. The highest values of Fcarb and Tcarb are in Asia and Oceania, and the highest Fsil and Tsil are in Oceania and South America. The RWCS flux has high-value areas near the equator. Both the flux and the total amount of RWCS are high in the tropics and warm temperate zones, while the cold zones also have high total amount of RWCS due to the presence of many large basins. The correlation analysis results indicate that the intensity of RWCS will depend mainly on precipitation, soil pCO and LAI. RWCS contributes to constraining the fate of the residual land sink.