Continental Run-Off as a Source of Osmium in Seawater

近年来，地球化学家和各种各样的地球科学家一直在寻找可靠的工具来应用于岩石记录，以了解地质历史中地球气候的变化。 在很大程度上，气候变化的主题还与大陆块风化速率的变化以及风化产物向世界海洋的输送和沉积相互交织。 近年来特别令人感兴趣的是海洋沉积记录中保存的锶同位素组成的变化，以及这种变化告诉我们大陆风化的速度。 然而，锶的一个问题是，它与钙的地球化学联系意味着它对风化的反应被（钙）碳酸盐-水的相互作用所缓冲。 在这个项目中，主要研究人员将对一种更可靠（或者至少被认为是更可靠的）风化古指示剂-痕量金属锇的化学进行基础研究。 锇在地球化学上与硅酸盐岩石有关，因为它的地球化学不受碳酸盐的缓冲，它在海洋沉积记录中的径流和保存应该比锶更准确地反映古气候变化和古风化作用。 这些研究将首次尝试确定河流沃茨和海水中锇的浓度和同位素组成。 这将是一项极具挑战性的分析任务;然而，在我们进一步探索这种痕量金属作为理解全球环境变化的工具的价值之前，必须进行这项工作。

In recent years, geochemists and a wide variety of earth scientists have searched for reliable tools to apply to the rock record in order to understand how the climate of earth has changed in the geologic past. To a great extent the subject of climatic change is also intertwined with changes in the rate of weathering of continental land masses and the transport and deposition of the weathering products to the world ocean. Of particular interest in recent years is the changing isotopic composition of strontium preserved in the marine sedimentary record and what that change tells us about the rate of continental weathering. One of the problems with strontium, however, is that its geochemical association with calcium means that its response to weathering is buffered by (calcium) carbonate - water interactions. In this project the principal investigator will carry out basic studies of the chemistry of a more reliable (or, at least, what is believed to be more reliable) weathering paleoindicator - the trace metal osmium.. Osmium is geochemically associated with silicate rock and, because its geochemistry is not buffered by carbonate, its runoff and preservation in the marine sedimentary record should more accurately reflect paleoclimatic change and paleoweathering than does strontium. These studies will attempt, for the first time, to determine the concentrations and isotopic compositions of osmium in river waters and seawater. This will be an exceedingly challenging analytical task; however, it is one that must be undertaken before we can further explore the value of this trace metal as a tool for understanding global environmental change.