The influence of land-surface reactivity on atmospheric carbon dioxide during past hyperthermals

在这项研究中，分析了海洋沉积物中的镁和锂同位素，以创建地球过去地质历史中硅酸盐化学和物理风化的时间序列。其目的是阐明硅酸盐风化对区域和全球变暖的响应，硅酸盐风化是大气二氧化碳浓度的主要控制因素。更温暖、更潮湿的气候应该会为地球表面发生的硅酸盐风化反应提供更多的能量和液体，消耗大气中的二氧化碳，扭转全球变暖的趋势。然而，如果硅酸盐风化产物在沉积到海洋沉积物之前在表层系统停留太长时间，它们会被转化回硅酸盐(反向风化)，释放消耗的二氧化碳，导致气候没有净变化。在过去的一年里，从几个国际大洋钻探计划(IODP)和大洋钻探计划(ODP)岩芯以及亚马逊边缘收集的200个沉积物样本被排序、干燥、粉碎和化学处理，以提取碳酸盐、氧化铁和硅酸盐相。目前正在从这些相中提纯镁，锂的进一步提纯仍有待进行。然后用电感耦合等离子体质谱测定镁和锂同位素。这项工作将提供数万至数百万年来区域(亚马逊)和全球变暖时期的过去风化记录，以帮助理解硅酸盐风化能力逆转全球变暖的能力。

In this study, marine sediments were analysed for magnesium and lithium isotopes to create a time-series of chemical and physical silicate weathering in the Earth’s geological past. The purpose is to elucidate the response of silicate weathering, which experts a major control on atmospheric CO2 concentration, to regional and global warming. A warmer, wetter climate should provide more energy and fluids for silicate weathering reaction at the Earth’s surface to occur, consuming atmospheric CO2 and reversing the global warming trend. However, if the products of silicate weathering remain in the surficial system for too long before being deposited in marine sediments, they are converted back to silicates (reverse weathering), remitting the consumed CO2 leading to no net change on climate.During the past fiscal year, 200 sediment samples from several International Ocean Drilling Program (IODP) and Ocean Drilling Program (ODP) cores collected from deep ocean basins as well as the Amazon margin were ordered, dried, crushed and chemically processed to extract the carbonate, iron oxide and silicate phase. Magnesium is currently being purified from these phases with further purification Li still to be conducted. Magnesium and Li isotopes with then be measured via inductively coupled plasma mass spectrometry. This work will provide records of past weathering during periods of regional (Amazonian) and global warming over tens of thousands to millions of years to help understand the silicate weathering capacity to reverse global warming.