美国科罗拉多大学 Shaily Rahman 使用稳定的硅同位素探测探测地球表面活性硅循环，取得了对其质量平衡、通量和深时含义的新理解。2023年12月8日出版的《科学进展》发表了这项成果。

研究人员收集了代表地球表面活性硅主要来源和汇的现代储层 δ ³⁰Si 数据，并对其应用了一个反演模型来检验关于其质量平衡的假设。结果表明，逆风化产物的 δ ³⁰Si 值与硅藻的 δ ³⁰Si 值非常接近，这与以往的假设相矛盾。

模型结果还显示，在硅酸盐矿物风化过程中每年释放的 19-21 teramoles 的硅中，每年约有 10-18 teramoles 的硅被储存在陆地硅汇中，这与不一致风化反应的假设一致。研究结果强调，现代硅循环是同位素质量守恒的。

据悉，地质储层 δ ³⁰Si 值越来越多地被用作古气候和古生产力的代用指标。许多这些应用都依赖于这样的假设，即地表 Si 同位素收支与整体硅酸盐地球存在质量平衡，因此 δ ³⁰Si 随时间的趋势可以归因于流入或流出关键硅储层的通量变化。

附：英文原文

Title: Probing surface Earth reactive silica cycling using stable Si isotopes: Mass balance, fluxes, and deep time implications

Author: Shaily Rahman, Elizabeth J. Trower

Issue&Volume: 2023-12-08

Abstract: Geological reservoir δ ³⁰Si values have increasingly been applied as paleoclimate and paleoproductivity proxies. Many of these applications rely on the assumption that the surface Earth Si isotope budget is in mass balance with bulk silicate Earth, such that trends in δ ³⁰Si over time can be attributed to changes in flux to or from key silica reservoirs. We compiled δ ³⁰Si data from modern reservoirs representing the major sources and sinks of surface Earth reactive silica, to which we applied an inverse model to test assumptions about mass balance. We found that δ ³⁰Si values of reverse weathering products must closely match those of diatoms, conflicting with previous assumptions. Model results also revealed that of the 19 to 21 teramoles per year Si released during silicate mineral weathering, ~10 to 18 teramoles per year is stored in terrestrial silica sinks, consistent with assumptions of incongruent weathering reactions. Our results demonstrated that the modern silica cycle summary is in isotopic mass balance.

DOI: adi2440

Source: https://www.science.org/doi/10.1126/sciadv.adi2440