CONTRIBUTION OF CARBONATE ROCK WEATHERING TO THE ATMOSPHERIC CO 2 SINK

To accurate1y predict future CO 2 levels in the atmosphere,which are crucial for predicting global climate change,the sources and sinks of the atmospheric CO 2 and their change with time must be determined.In this paper,case studies are reviewed using published and unpublished data.First1y the sensitivity of carbonate rock weathering(including the effects of both dissolution and reprecipitation of carbonate) to the change of soil CO 2 and run off is discussed,and then the net amount of CO 2 absored from the atmosphere by the carbonate rock in the mainland of China and the world is determined by the hydrochemical discharge method and carbonate rock tab1et method,to obtain an estimate of the contribution of carbonate rock weathering to the atmospheric CO 2 sink. These contributions are about 0 018 billion metric tons of carbon every year and 0.11 billon metric tons of carbon every year in China and the world,respectively. Furthermore,according to the DBL (Diffusion Bonddary Layer) model calculation,the CO 2 sink by carbonate rock dissolution is estimated to be 0.41 billion metric tons of carbon every year in the wor1d.Therefore,the potential CO 2 source by carbonate reprecipitation is 0.3 billon metric tons of carbon every year.