The Geochemistry of U, Re, Mo in Margin and Coastal Sediments

海洋沉积物中Mo、Re和U的富集速率可以作为重建过去氧化还原条件的有效指标。虽然自生Mo、Re和U积累速率的增加通常是沉积物中还原条件增加的明确指示，但很难推断这种变化是由于底部水氧含量的减少还是有机碳通量的增加。来自伍兹霍尔海洋研究所的三位科学家计划开发一种方法来区分这两种潜在的原因，利用从华盛顿边缘获得的孔隙水样本和从Buzzards湾（沿海地区）的季节性沉积物中获得的样本。pi将使用底栖通量室、离心和原位聚丙烯酰胺凝胶探针获取这些样品。孔隙水和固相样品将分析U， Re和Mo以及必要的支持参数。从Buzzards湾获得的剖面结果将用于记录孔隙水浓度和底栖生物通量的季节性演变，作为生物扰动、生物灌溉和非稳态O2渗透到沉积物中的函数。来自华盛顿边缘地区的样品将用于评估水深、碳通量和底水O2浓度对这些氧化还原敏感金属埋藏的影响。这项研究的结果将被纳入稳态沉积物-孔隙水模型，以使用导出的参数来获得真实的固相金属剖面。

ABSTRACTOCE-0220892The accumulation rates of Mo, Re and U in marine sediments can be useful proxies for reconstructing past redox conditions. While an increase in accumulation rates of authigenic Mo, Re and U is often a clear indication of more reducing conditions in sediments, it is more difficult to deduce whether the change is due to a decrease in bottom water oxygen content or an increase in organic carbon flux. Three scientist from Woods Hole Oceanographic Institution plan to develop a means of distinguishing between these two potential causes utilizing porewater samples obtained from the Washington margin and seasonally from sediments in Buzzards Bay (coastal site). The PIs will acquire these samples using benthic flux chambers, centrifugation and in-situ polyacrylamide gel probes. The porewater and solid phase samples will be analyzed for U, Re and Mo as well as the necessary supporting parameters. Results from the profiles obtained at Buzzards Bay will serve to document the seasonal evolution of porewater concentrations and benthic fluxes as a function of bioturbation, bioirrigation and non-steady state O2 penetration into the sediments. Samples from the Washington margin region will be used to assess the influence of water depth, carbon flux and O2 bottom water concentrations on the burial of these redox sensitive metals. Results from this study will be incorporated into a steady-state sediment-pore water model to use the derived parameters to obtain realistic solid phase metal profiles.