环境地球化学国家重点实验室知识库

It is widely accepted that chemical weathering of Ca-silicate rocks could potentially control long-term climate change by providing feedback interaction with atmospheric CO(2) drawdown by means of precipitation of carbonate, and that in contrast weathering of carbonate rocks has not an equivalent impact because all of the CO(2) consumed in the weathering process is returned to the atmosphere by the comparatively rapid precipitation of carbonates in the oceans. Here, it is shown that the rapid kinetics of carbonate dissolution and the importance of small amounts of carbonate minerals in controlling the dissolved inorganic C (DIC) of silicate watersheds, coupled with aquatic photosynthetic uptake of the weathering-related DIC and burial of some of the resulting organic C, suggest that the atmospheric CO(2) sink from carbonate weathering may previously have been underestimated by a factor of about 3, amounting to 0.477 Pg C/a. This indicates that the contribution of silicate weathering to the atmospheric CO(2) sink may be only 6%, while the other 94% is by carbonate weathering. Therefore, the atmospheric CO(2) sink by carbonate weathering might be significant in controlling both the short-term and long-term climate changes. This questions the traditional point of view that only chemical weathering of Ca-silicate rocks potentially controls long-term climate change.