Contribution of carbonate rock weathering to the atmospheric CO2 sink

To accurately predict future CO2 levels in the atmosphere, which is crucial in predicting global climate change, the sources and sinks of the atmospheric CO2 and their change over time must be determined. In this paper, some typical cases are examined using published and unpublished data. Firstly, the sensitivity of carbonate rock weathering (including the effects by both dissolution and reprecipitation of carbonate) to the change of soil CO2 and runoff will be discussed, and then the net amount of CO2 removed from the atmosphere in the carbonate rock areas of mainland China and the world will be determined by the hydrochem-discharge and carbonate-rock-tablet methods, to obtain an estimate of the contribution of carbonate rock weathering to the atmospheric CO2 sink. These contributions are about 0.018 billion metric tons of carbonla and 0.11 billion metric tons of carbonla for China and the world, respectively. Further, by the DBL (Diffusion Boundary Layer)-model calculation, the potential CO2 sink by carbonate rock dissolution is estimated to be 0.41 billion metric tons of carbonla for the world. Therefore, the potential CO2 source by carbonate reprecipitation is 0.3 billion metric tons of carbon/a.