Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, 24061, USA.
Department of Earth, Ocean and Atmospheric Science & National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida, 32306, USA.
Sci Rep. 2017 Jul 10;7(1):5003. doi: 10.1038/s41598-017-05307-y.
Chemical weathering consumes atmospheric carbon dioxide through the breakdown of silicate minerals and is thought to stabilize Earth's long-term climate. However, the potential influence of silicate weathering on atmospheric pCO levels on geologically short timescales (10-10 years) remains poorly constrained. Here we focus on the record of a transient interval of severe climatic warming across the Toarcian Oceanic Anoxic Event or T-OAE from an open ocean sedimentary succession from western North America. Paired osmium isotope data and numerical modelling results suggest that weathering rates may have increased by 215% and potentially up to 530% compared to the pre-event baseline, which would have resulted in the sequestration of significant amounts of atmospheric CO. This process would have also led to increased delivery of nutrients to the oceans and lakes stimulating bioproductivity and leading to the subsequent development of shallow-water anoxia, the hallmark of the T-OAE. This enhanced bioproductivity and anoxia would have resulted in elevated rates of organic matter burial that would have acted as an additional negative feedback on atmospheric pCO levels. Therefore, the enhanced weathering modulated by initially increased pCO levels would have operated as both a direct and indirect negative feedback to end the T-OAE.
化学风化通过硅酸盐矿物的分解消耗大气中的二氧化碳，被认为可以稳定地球的长期气候。然而，硅酸盐风化对大气 pCO 水平在地质短时间尺度（10-10 年）上的潜在影响仍然难以确定。在这里，我们关注的是来自北美西部开阔海洋沉积序列的记录，记录了整个 Toarcian 海洋缺氧事件或 T-OAE 期间一段气候剧烈变暖的短暂间隔。成对的锇同位素数据和数值模拟结果表明，与事件前基线相比，风化速率可能增加了 215%，甚至可能增加了 530%，这将导致大量大气 CO 的封存。这一过程还将导致更多的营养物质输送到海洋和湖泊中，刺激生物生产力，并导致随后浅水缺氧的发展，这是 T-OAE 的标志。这种增强的生物生产力和缺氧将导致有机物质埋藏率的升高，这将对大气 pCO 水平产生额外的负反馈。因此，最初增加的 pCO 水平所调节的增强风化作用将成为结束 T-OAE 的直接和间接负反馈。
