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

虽然只有很少的数据，河流通常被认为是主要来源的颗粒反应元素Zr，Hf，Nb和Ta的海洋。然而，缺乏对这些元素从大陆到海洋的迁移的系统研究，以及对不同地质和环境条件对其地球化学行为的影响的正确理解。沿着从陆地到海洋的通道的大黑盒子是河口，在那里淡水和海水的混合物深刻地影响了粒子反应元素进入海洋的河流通量。本研究讨论了格陵兰北部和温带河水以及冰川融水河流中Zr、Hf、Nb和Ta的分布以及Hf同位素组成，同时考虑到这些元素与淡水中不同物理微量元素库（即颗粒物）的关系。（>0.2μm）、纳米颗粒/胶体（0.2μm至1 KD）和真正溶解的（<1 KD）池。通过淡水和海水端元之间的混合实验，将研究这些元素向海水的净河流通量及其对海洋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。这项研究的结果将显着提高我们的运输和命运的Zr，Hf，Nb和Ta在淡水和他们的途径从大陆到海洋在不同的地质和环境条件下的理解。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同位素组成的作用。

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.