Chemical weathering processes and atmospheric CO₂ consumption of Huanghe River and Changjiang River basins

Rock weathering plays an important role in studying the long-term carbon cycles and global climatic change. According to the statistics analysis, the Huanghe (Yellow) River water chemistry was mainly controlled by evaporite and carbonate weathering, which were responsible for over 90% of total dissolved ions. As compared with the Huanghe River basin, dissolved load of the Changjiang (Yangtze) River was mainly originated from the carbonate dissolution. The chemical weathering rates were estimated to be 39.29t/(km² •a) and 61.58t/(km² •a) by deducting the HCO'3^- derived from atmosphere in the Huanghe River and Changjiang River watersheds, respectively. The CO₂ consumption rates by rock weathering were calculated to be 120.84 × 10³ mol/km² and 452.46 × 10³mo1/km² annually in the two basins, respectively. The total CO₂ consumption of the two basins amounted to 918.51 × 10⁹mo1/a, accounting for 3.83% of the world gross. In contrast to other world watersheds, the stronger evaporite reaction and infirm silicate weathering can explain such feature that CO₂ consumption rates were lower than a global average, suggesting that the sequential weathering may be go on in the two Chinese drainage basins.