美国宾夕法尼亚大学地球与环境学院系统研究所的S. L. Brantley课题组近日取得一项新成果。他们分析了由温度决定的硅酸盐风化作用是如何成为地球的地质恒温器的。相关论文于2023年1月27日发表在《科学》杂志上。

研究团队发现，从实验室到流域，风化作用以活化能表示的温度依赖性随着运输、粘土沉淀、崩解和破裂与溶解的耦合越来越大而增加。对全球系统进行简单的升级，表明温度依赖性降低到每摩尔约22千焦，因为(i)径流的缺乏限制了风化作用，将贱金属阳离子保留在一半的陆地表面；(ii)其他景观受风化层保护，对温度的风化作用响应很小。通过对比实验室和全球的风化作用，研究人员调和了自然或增强风化作用对二氧化碳下降的动力学和热力学控制的某些方面。

据悉，随着矿物风化，大气中二氧化碳(CO₂)的溶解可能会使地球气候稳定数千年，但人们对这种恒温器的温度敏感性知之甚少。

附：英文原文

Title: How temperature-dependent silicate weathering acts as Earth’s geological thermostat

Author: S. L. Brantley, Andrew Shaughnessy, Marina I. Lebedeva, Victor N. Balashov

Issue&Volume: 2023-01-27

Abstract: Earth’s climate may be stabilized over millennia by solubilization of atmospheric carbon dioxide (CO₂) as minerals weather, but the temperature sensitivity of this thermostat is poorly understood. We discovered that the temperature dependence of weathering expressed as an activation energy increases from laboratory to watershed as transport, clay precipitation, disaggregation, and fracturing increasingly couple to dissolution. A simple upscaling to the global system indicates that the temperature dependence decreases to ~22 kilojoules per mole because (i) the lack of runoff limits weathering and retains base metal cations on half the land surface and (ii) other landscapes are regolith-shielded and show little weathering response to temperature. By comparing weathering from laboratory to globe, we reconcile some aspects of kinetic and thermodynamic controls on CO₂ drawdown by natural or enhanced weathering.

DOI: add2922

Source: https://www.science.org/doi/10.1126/science.add2922