Petrogenic Organic Carbon Weathering and a Geological Carbon Budget in the Yangtze River Basin

Abstract As a crucial component of the geological carbon cycle, the weathering process of petrogenic organic carbon (OC petro ) remains poorly constrained on a continental scale, largely due to interference from anthropogenic activities. This uncertainty introduces substantial biases into assessments of the geological carbon budget. To address this, we analyzed major ions and rhenium (Re) concentrations in water samples from the Yangtze River Basin, employing a Monte‐Carlo inversion model to eliminate anthropogenic signals and quantify natural weathering flux. Our results indicate that anthropogenic inputs contribute over 50% of the total dissolved Re flux in the Yangtze River. After correcting for these anthropogenic perturbations, we derived a high‐temporal‐resolution record of OC petro weathering rates for the basin, with an annual average of 2.14 tC km −2 yr −1 . The associated CO 2 release from OC petro weathering is comparable in magnitude to the CO 2 drawdown from silicate weathering, implying that OC petro weathering constitutes a non‐negligible component of the net geological carbon budget of the Yangtze River Basin, China.