Molybdenum Isotope Geochemistry in Marine Sediments II: Experimental Determinations of Mo Isotope Fractionation Under Sulfidic Conditions

过渡元素在海洋碳和氧循环中起着至关重要的作用，特别是因为它们的稳定同位素为追踪或量化海洋中过去和现在的化学过程提供了巨大的潜力。钼（Mo）的海洋地球化学以各种同位素特征的形成为主导，具有作为古氧化还原指示物的巨大潜力。在室内进行了氧环境中Mo分馏定量实验；然而，还没有对还原条件下的Mo分馏进行实证研究。俄勒冈州立大学的一位科学家提出了一系列实验，以确定硫化氢海洋环境中Mo同位素分馏的地球化学机制。假设还原性大陆边缘海相沉积物中Mo同位素组成受硫化物对黄铁矿的吸附控制。为了验证这一假设，将进行一系列实验来测量硫化物控制的Mo同位素分馏。为了解释海洋沉积物中Mo同位素的变化，需要定量地了解Mo同位素的行为。就更广泛的影响而言，首席研究员计划与纽卡斯尔大学的一位科学家合作。作为该项目的一部分，一名高中生和一名研究生将得到支持和培训。

Transition elements play an essential role in the marine carbon and oxygen cycles, particularly because their stable isotopes offer significant potential for tracing or quantifying past and present chemical processes in the ocean. Molybdenum (Mo), whose marine geochemistry is dominated by the formation of various isotopic signatures, indicates significant potential as a paleoredox indicator.Laboratory experiments quantifying Mo fractionation in oxic environments have been carried out; however, Mo fractionation under reducing conditions have not been empirically investigated. A scientist from Oregon State University proposes a series of experiments to determine the geochemical mechanisms responsible for fractionating Mo isotopes in sulfidic marine environments. It is hypothesized that Mo isotope compositions in reducing continental margin marine sediments are controlled by Mo-sulfide adsorption to pyrite. To test the hypothesis, a suite of experiments would be done to measure sulfide-controlled Mo isotope fractionation. Achieving a quantitative understanding of Mo isotope behavior is needed for interpretating Mo isotope variations in the marine sediment record.In terms of the broader impacts, the principal investigator plans to collaborate with a scientist at Newcastle University. One high school student and one graduate student would be supported and trained as part of this project.