Consumption of atmospheric CO2 via chemical weathering in the Yellow River basin: The Qinghai–Tibet Plateau is the main contributor to the high dissolved inorganic carbon in the Yellow River

• High DIC in the Yellow River originates from Qinghai–Tibet Plateau.
• Carbonate dominates chemical weathering in the whole Yellow River basin.
• CO2 consumption in the Yellow River basin reaches 98.31 × 109 mol/a.

The high HCO3− concentrations in the Yellow River (China) are generally believed to originate primarily from the carbonate-rich Loess Plateau as a result of carbonate weathering reactions that consume atmospheric CO2. We studied chemical weathering across the entire Yellow River basin in 2007 and 2009 and found that the amounts of CO2 consumption by carbonate and silicate weathering were 87.61 × 109 mol/a and 10.70 × 109 mol/a, respectively. As the source of water for the Yellow River, although the Qinghai–Tibet Plateau accounts for only 30% of the area of the basin, it has a strong leaching effect and contributes a majority (61%) of the atmospheric CO2 consumption of the entire basin and a majority of the riverine DIC flux (66%) to the ocean. As a result, the dissolved inorganic carbon (DIC) concentrations in this river are among the highest of the world's major rivers. In contrast, despite the abundant carbonate mineral content in the Loess Plateau, the high ratio of evaporation to precipitation (4.2) limits the weathering processes, and the low amount of runoff restricts the transport of weathering products, which results in a relatively low contribution (38%) to the basin-wide atmospheric CO2 consumption, which is much lower than was previously thought. The Qinghai–Tibet Plateau is the origin of the high levels of HCO3− in and acts as the main DIC contributor to the Yellow River.