Osmium Isotopes in Seawater

迄今为止关于锇的海洋地球化学的工作指出，需要限制海洋的Os同位素组成，以便从更容易进行的沉积物和锰结核测量中得出宇宙和陆地的Os通量。如果不至少对该元素的海洋学行为有一个一级的了解，海洋的os同位素组成就不能得到适当的评估。本研究将通过测定其在海水中的分布和同位素组成来阐明Os的海洋化学。再加上对海洋固相的独立但兼容的研究，该项目将大大增加我们对这种元素的海洋地球化学循环的整体理解。这些基础工作是开发该同位素系统探测海洋地球化学过程潜力的先决条件。海水中的os同位素系统是否均匀，将决定其沉积特征是在全球尺度上记录其地壳、地幔和宇宙成因的相对量级，还是追踪更多影响其聚集的局部过程。这反过来又决定了古宇宙物质通量或海洋的古氧化还原状态是否可以从Os的沉积记录中重建。在更直接的时间尺度上，了解水柱中Os的行为将为在受影响的沿海地区和封闭盆地中使用人为Os作为示踪剂提供基础。

The work to date on the marine geochemistry of osmium points to the need to constrain the Os-isotopic composition of the oceans in order to derive cosmic and terrestrial Os fluxes from the more readily conducted measurements on sediments and Mn-nodules. The Os-isotopic composition of the oceans cannot be properly assessed without at least a first order understanding of the oceanographic behavior of the element. This research will elucidate the marine chemistry of Os through determination of its distribution and isotopic composition in seawater. Together with a separate but compatible study of marine solid phases, the project will significantly increase our overall comprehension of the marine geochemical cycle of this element. Such groundwork is prerequisite to exploiting the potential of this isotopic system for probing marine geochemical processes. Whether the Os-isotopic system in seawater is homogeneous will determine if its sedimentary signature records the relative magnitudes of its crustal, mantle and cosmogenic sources on the global scale or if it traces more local processes affecting its accumulation. This in turn determines whether the paleo cosmogenic material flux or the paleo-redox state of the oceans might be reconstructed from sedimentary records of Os. On a more immediate timescale, an understanding of the behavior of Os in the water column will provide the basis for using anthropogenic Os as a tracer in affected coastal areas and enclosed basins.