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大陆化学风化显著影响全球气候变化、地表物质循环和海水化学组成,如何定量地重建古化学风化历史一直是全球变化研究的热点.化学蚀变指数(CIA)被广泛用作衡量大陆硅酸盐岩化学风化程度的定量指标,其指示意义在前人研究中不断深化,但对其具体计算方法和运用局限性缺乏深入探讨.研究长江干支流悬浮物的CIA值在时空上的变化特征,揭示出CIA季节性的变化反映长江流域季节性降雨区迁移导致下游干流悬浮物来源的不同,由此提出CIA实际反映了流域累积的综合化学风化历史,而不是一个可靠的瞬时(季节性)化学风化指标,不能指示短时间尺度的季节性气候变化.通过比较不同计算方法和沉积粒度对CIA的影响,提出在CIA应用过程中应该注意的关键问题.
The chemical weathering of the mainland has significantly affected the global climate change, the surface material circulation and the chemical composition of the sea water, and how to quantitatively reconstruct the paleo-chemical weathering history has been a hot topic in the global change research.Chemistry alteration index (CIA) is widely used to measure the continental silicate rock Quantitative indicators of the degree of chemical weathering, the significance of its instructions in the predecessors continue to deepen the study, but its specific calculation methods and limitations of the lack of in-depth study.Changzhou Changshu suspended matter CIA value changes in space-time characteristics, revealing The seasonal variation of CIA reflects the different source of suspended matter in the downstream mainstream due to the seasonal precipitation in the Yangtze River Basin. It is suggested that the CIA actually reflects the cumulative chemical weathering history accumulated in the basin instead of a reliable instantaneous (seasonal) chemical weathering index , Can not indicate seasonal climate change on a short time scale.Through comparing the influence of different calculation methods and sedimentation particle size on CIA, the key problems that should be noticed in the application of CIA are put forward.