碳酸盐风化碳汇与森林碳汇的对比——碳汇研究思路和方法变革的必要性

目前,全球碳循环研究主要集中在海洋碳汇以及陆地土壤和植被碳汇,而对岩石风化碳汇仅考虑地质长时间尺度的硅酸盐风化作用,而认为碳酸盐风化在长时间尺度上对碳汇无贡献。然而,碳酸盐相对于硅酸盐有快得多的溶解速度,且对全球变化(特别是气候和CO2变化)的响应迅速,同时由于生物作用和人为活动的影响,使得碳酸盐风化碳汇的能力需要重新评价。最新的研究发现,由碳酸盐溶解、全球水循环及水生生物光合利用溶解无机碳共同作用,即水-岩-气-生相互作用形成的大气碳汇,远远大于之前只估计了河流输运的无机碳汇,其量级与森林碳汇量相当,因此有必要对传统的碳汇研究思路和方法进行某些变革,这有可能为解决所谓的全球“碳失汇”问题找到一条出路。 

Comparison of carbon sequestration capacity between carbonate weathering and forests: The necessity to change traditional ideas and methods of study of carbon sinks

At present, researches on the modern global carbon cycle focuses mainly on carbon sinks caused by the oceans and the terrestrial soils and vegetation. In addition, chemical weathering of Ca-silicate rocks is considered to have the potential in controlling long-term climate change by providing feedback interactions with atmospheric CO2 drawdown by means of the precipitation of carbonate. In contrast, carbonate weathering itself has not been given equivalent attention although it is much more rapid than silicate weathering and more sensitive to global changes (especially climate and CO2 change).Further, biological and human activities also significantly influence carbonate weathering. Thus, the contribution of carbonate weathering to the atmospheric CO2 sink should be re-evaluated. Latest studies show that the carbon sink through the combined action of carbonate dissolution, the global water cycle, and photosynthetic uptake of dissolved inorganic carbon by aquatic organisms (i.e., by carbonate weathering via the water-rock-gas-organism interaction) is far greater than previous estimates that have only considered the transport of dissolved inorganic carbon by rivers, and have a similar magnitude to that of the terrestrial carbon sink in global forests. Therefore, changes in traditional ideas and methods of carbon sink study are necessary, and may provide a way to solve the so called global “missing carbon sink “problem.