26AI and 10Be: Oceanic Fractionation and Tracer Utilities

小行星9633469 地球上的放射性26 Al（半衰期0.7 My）和10 Be（1.5 My）是由宇宙射线与大气层和岩石表面的原子相互作用产生的。它们主要通过湿/干沉降物进入海洋，几乎恒定的比例主要反映了它们在大气中的生产率。虽然这些宇宙成因放射性核素及其稳定同位素（9 Be和27 A1）的源函数不同，但它们在地球化学库中的路径通过同位素亲缘关系联系在一起。 总之，这些同位素可以在地球物理研究中用作强大的时间和过程示踪剂。 这种示踪剂的研究已成为可行的，最近在分析技术，特别是测量海洋材料中的26铝的能力的改进。将测量沉积物中的自生10 Be/9 Be比率，沉积物中的10 Be、26 Al和U-未支持的230 Th的浓度，悬浮颗粒物和沉积物捕集材料，以及海水中的10 Be和7 Be。这些测量将有助于我们了解海洋26 Al-10 Be分馏和分布的控制因素，并有助于我们使用10 Be/26 Al的沉积信号来追踪古生产力，26 Al/230 Th来追踪过去宇宙线强度的变化。此外，26 Al、10 Be和7 Be将用于评估水柱中的粒子通量变化和粒子动力学。

9633469 KU Radioactive 26Al (half-life 0.7 My) and 10Be (1.5 My) on the earth are produced by the interaction of cosmic rays with atoms in the atmosphere and in the surface of rocks. They enter the ocean chiefly via wet/dry fallout, with nearly constant proportions primarily reflecting their atmospheric production ratios. Although these cosmogenic radionuclides and their stable isotopes (9Be and 27A1) differ in source functions, their pathways in geochemical reservoirs are linked through the isotopic kinship. Together, these isotopes can be used as powerful time and process tracers in geophysical studies. Such tracer studies have become feasible with recent improvements made in the analytical techniques, particularly the ability to measure 26Al in marine materials. Measurements will be made of authigenic 10Be/9Be ratios in sediments, concentrations of 10Be, 26Al, and U-unsupported 230Th in sediments, suspended particulate matter and sediment-trap material, and 10Be and 7Be in sea water. These measurements will improve our understanding of the factors governing the oceanic 26Al-10Be fractionation and distribution, and facilitate our use of the sedimentary signals of 10Be/26Al to trace paleoproductivity, and 26Al/230Th to trace past variations of cosmic-ray intensity. In addition, 26Al, 10Be and 7Be will be used to evaluate particle flux variations and particle dynamics in the water column.