Riverine fluxes of high field strength elements Zr, Hf, Nb, Ta into the oceans and their impact on the Hf isotopic composition of seawater

高场强元素Zr、Hf、Nb、Ta流入海洋的河流通量及其对海水Hf同位素组成的影响

• 批准号: 273947145
• 负责人: Dr. Katja Schmidt
• 金额: --
• 依托单位: Department of Physics and Earth Sciences
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2015
• 资助国家: 德国
• 起止时间: 2014-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/273947145?language=en
• 关键词: Riverine; fluxes; field; strength; elements

Although there are only little data available, rivers are commonly assumed to be the major source of the particle-reactive elements Zr, Hf, Nb, and Ta to the oceans. However, a systematic investigation of the transport of these elements from the continents to the oceans and a proper understanding of the impact of different geological and environmental conditions on their geochemical behavior are lacking. The large black box along the pathway from land to sea are the estuaries where the mixture of freshwater with seawater profoundly affects the riverine flux of particle-reactive elements into the ocean. This study addresses the distribution of Zr, Hf, Nb and Ta, and the Hf isotopic composition in boreal and temperate river water and in glacial melt water rivers in Greenland, taking into account the association of such elements with the different physical trace element pools in freshwater, i.e. the particulate (>0.2µm), the nanoparticle/colloid (0.2µm to 1 KDa), and the truly dissolved (<1KD) pools. The net riverine flux of these elements to seawater and its impact on the Hf isotopic composition of the oceans will be investigated by mixing experiments between the freshwater and seawater endmembers. The complex method work includes filtration and ultrafiltration steps and subsequent preconcentration steps. The outcome of this study will significantly enhance our understanding on the transport and fate of Zr, Hf, Nb, and Ta in freshwater and their pathways from the continents into the ocean at different geological and environmental conditions. The results for the Hf isotopes will help to better address the role of continental weathering and runoff conditions in controlling the Hf isotopic composition of seawater.

尽管只有很少的数据可用，但河流通常被认为是进入海洋的粒子反应元素Zr、Hf、Nb和Ta的主要来源。然而，缺乏对这些元素从大陆到海洋的运输的系统调查，以及对不同地质和环境条件对其地球化学行为的影响的适当了解。从陆地到海洋的路径上的大黑匣子是河口，在那里淡水和海水的混合物深刻地影响着流入海洋的颗粒反应元素的河流流量。本文研究了格陵兰岛北部和温带河水以及冰川融水河流中的Zr、Hf、Nb、Ta的分布和Hf同位素组成，并考虑了这些元素与淡水中不同物理微量元素池的关系，即颗粒(&gt；0.2µm)、纳米颗粒/胶体(0.2µm~1 KDa)和真正溶解的(&lt；1KD)池。将通过淡水和海水端元之间的混合实验来调查这些元素向海水的河流净通量及其对海洋Hf同位素组成的影响。复杂的方法工作包括过滤和超滤步骤以及随后的预浓缩步骤。这项研究的结果将大大加深我们对不同地质和环境条件下淡水中Zr、Hf、Nb和Ta的迁移和去向以及它们从大陆进入海洋的途径的理解。Hf同位素的结果将有助于更好地解决大陆风化和径流条件在控制海水Hf同位素组成方面的作用。