英国伦敦大学伯贝克学院Philip A. E. Pogge von Strandmann研究小组在研究中取得进展。他们的最新研究提出了对碳和硅循环演化的锂同位素观点。2021年7月14日，国际知名学术期刊《自然》发表了这一成果。
该研究组认为锂同位素记录可以用来跟踪长期控制碳和硅循环的过程。通过分析来自100多个地层单元的600多个浅水海相碳酸盐岩样品，该课题组构建了一个跨越过去30亿年的新的碳酸盐岩锂同位素记录。这些数据表明，碳酸锂同位素值随着时间的推移而增加，该团队认为这是由海水的锂同位素条件的长期变化所驱动的，而不是由较老样品的沉积改变所驱动的。
利用质量平衡模拟方法，该课题组研究人员认为锂同位素的变化趋势反映了前寒武纪碳硅循环向现代碳硅循环的转变。该课题组推测这种转变与生物控制的海洋硅循环的逐渐转变和陆地植物的进化辐射有关。
研究人员表示，全球碳和硅循环的演化被认为对地球气候的长期稳定有贡献。然而，关于起作用的反馈机制仍存在许多问题，这些元素在地球表面环境中的分布和汇流也受到有限的定量限制。
附：英文原文
Title: A lithium-isotope perspective on the evolution of carbon and silicon cycles
Author: Boriana Kalderon-Asael, Joachim A. R. Katchinoff, Noah J. Planavsky, Ashleigh v. S. Hood, Mathieu Dellinger, Eric J. Bellefroid, David S. Jones, Axel Hofmann, Frantz Ossa Ossa, Francis A. Macdonald, Chunjiang Wang, Terry T. Isson, Jack G. Murphy, John A. Higgins, A. Joshua West, Malcolm W. Wallace, Dan Asael, Philip A. E. Pogge von Strandmann
Issue&Volume: 2021-07-14
Abstract: The evolution of the global carbon and silicon cycles is thought to have contributed to the long-term stability of Earth’s climate1,2,3. Many questions remain, however, regarding the feedback mechanisms at play, and there are limited quantitative constraints on the sources and sinks of these elements in Earth’s surface environments4,5,6,7,8,9,10,11,12. Here we argue that the lithium-isotope record can be used to track the processes controlling the long-term carbon and silicon cycles. By analysing more than 600 shallow-water marine carbonate samples from more than 100 stratigraphic units, we construct a new carbonate-based lithium-isotope record spanning the past 3 billion years. The data suggest an increase in the carbonate lithium-isotope values over time, which we propose was driven by long-term changes in the lithium-isotopic conditions of sea water, rather than by changes in the sedimentary alterations of older samples. Using a mass-balance modelling approach, we propose that the observed trend in lithium-isotope values reflects a transition from Precambrian carbon and silicon cycles to those characteristic of the modern. We speculate that this transition was linked to a gradual shift to a biologically controlled marine silicon cycle and the evolutionary radiation of land plants13,14.
DOI: 10.1038/s41586-021-03612-1
Source: https://www.nature.com/articles/s41586-021-03612-1