硅酸盐风化与全球碳循 环研究回顾及新进展

硅酸盐风化是大气CO2 的一个主要汇，直接影响到全球碳循环进而影响全球气候。自Walker 等（1981）进行的开创 工作以来，有关“硅酸盐风化- 碳循环- 气候变化”方面的研究大量涌现。从计算机模型到河流水化学研究，从流域面积 超过百万平方公里的大河到数十数百平方公里的单岩性小河流，取得了很多重要的进展。从全球尺度上看，硅酸盐风化每 年所消耗的大气CO2 量为0.138~0.169 Gt，相比现在大气碳库中碳的含量（约800 Gt），乍看似乎是微不足道的，然而硅酸盐 风化消耗CO2 并将其作为碳酸盐矿物埋藏在海洋，它的存留时间超过了百万年。因此，在地质时间尺度上，硅酸盐风化是 调节全球碳循环的一个重要机制。对小流域进行的研究发现，热带地区流经玄武岩/蛇绿岩的小流域有着最高的硅酸盐风化 和大气CO2 消耗速率，热带区域火山岩化学风化消耗的大气CO2 占全球硅酸盐风化所消耗量的10%，而流域面积不到1%。

Review and Advancements of Studies on Silicate Weathering and the Global Carbon Cycle

Silicate weathering is a major sink of the atmospheric CO 2,which directly affects the global carbon cycle and the climate.Since the pioneering work of Walker et al.(1981),studies on"silicate weathering,carbon cycle and climate changes" have sprung up in recent years.Many advancements have been obtained from computer models to river water geochemistry and from large rivers with a drainage area exceeding to 10 6 km 2 to monolithologic small watershed with tens/hundreds km 2 drainage area,.In the global scale,atmospheric CO 2 consumption from silicate weathering is about 0.138-0.169 Gt per year.Compared to the current atmospheric carbon content of 800 Gt,at first glance,this CO 2 consumption rate seems so slow that silicate weathering would play only a negligible role in the global carbon cycle.However,atmospheric CO 2 removed from silicate weathering is transported by rivers and thereafter precipitated in the ocean as carbonate minerals,and the residence time of carbon in carbonate rocks is in excess of millions of years.Therefore,silicate weathering is an important mechanism that modulates the long-term carbon cycle.Moreover,researches show that the small watersheds draining basalts/ophiolites in the tropical zones have the highest silicate weathering and CO 2 consumption rates.It is estimated that CO 2 consumption from volcanic rocks in the tropical zones represents about 10% of the global export of carbon by silicate weathering,while the tropical volcanic arcs correspond to only～1% of the exorheic drainage area worldwide.