用放射性示踪技术研究海洋沉积物中铱的吸附和解吸行为及其富集机制

利用放射性示踪技术，结合静态吸附、解吸实验及可见分光光度分析，研究了海洋沉积物－海水体系中铱的吸附及解吸行为。结果表明，在极低的铱浓度范围内，铱的吸附－解吸等温线呈线性，咀吸附－解吸不可逆。IrCl6%2-形态的铱极易被沉积物所吸附，一旦吸附后又难解吸焉。沉积物沉积过程中不断地吸附海水中的IrCl6^2-，可能致使铱累积于沉积物中，从而引起铱富集，丹麦鱼粘土对铱的吸附能力弱于近海洋沉积物，说明丹麦鱼粘土高含量铱来源于其它成因控制，如火山或地外成因。

Study on sorption,desorption behaviors and enrichment mechanism of iridium in marine sediments by radioactive tracer

By using radiotracer technique, the sorption and desorption behaviors of iridium in marine sediment-seawater system were studied through the sorption and desorption experiments and visible absorption spectrum analysis. The results indicated that, in the range of very low iridium concentration, the sorption and desorption isotherms were linear, and the sorption-desorption process was irreversible. Iridium in the form of IrCl62- was very easy to be sorbed by the sediments. Once being sorbed by the sediments, Ir was hard to be desorbed. In the sedimentary process, the sediment continuously absorbed the species of IrCl62- from the seawater, which might lead to the Ir accumulation in the sediment. The sorption ability of the Danish K/T Fish Clay was weaker than that of the coastal sediment, which indicated that the excessively high Ir content in the Fish Clay might be caused by the other enrichment mechanisms, such as volcanic or extraterrestrial origin.