Continental Run-Off as a Source of Osmium in Seawater

点击翻译按钮获取中文摘要

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.