Geochemistry of natural and anthropogenic rare earth elements in rivers with emphasis on the Rhine River and its tributaries

在原始环境中，稀土元素是理想的地球化学示踪剂。然而，在世界各地的许多河流中都发现了用于计算机断层扫描造影剂的人为钆（Gd），莱茵河的初步样本甚至显示出镧（La）的强烈人为富集。La的来源尚不清楚，但与人为的Gd一起，在饮用水中也观察到这种La化合物。在该项目中，将研究莱茵河及其支流中稀土元素的分布。在随后的两个低流量和高流量时期，将确定流域地质、自然河流流量和人为输入对稀土元素分布的（季节性）影响，并确定未知镧微污染物的来源。对莱茵河沿岸主要城市饮用水的研究将作为补充。拟议的项目将加强我们对自然环境中高科技元素的地球化学行为的理解。考虑到高科技产品和工艺中稀土元素的使用正在急剧增加，研究结果对决策也很重要。

In pristine environments, the rare earth elements (REE) are ideal geochemical tracers. However, anthropogenic gadolinium (Gd) used in contrast agents in computer tomography has been found in numerous rivers worldwide and preliminary samples from the Rhine River even show a strong anthropogenic enrichment of lanthanum (La). The La source is not yet known, but together with the anthropogenic Gd, this La compound is also observed in drinking water. During the proposed project, the distribution of the REE will be studied in the Rhine River and its tributaries. The (seasonal) impact of catchment geology, natural river discharge and anthropogenic input on the REE distribution will be determined during two subsequent low-discharge and high-discharge periods and the source of the unknown La rnicrocontaminant will be located and characterized. This will be complemented by the study of drinking water in major cities along the Rhine River. The proposed project will enhance our understanding of the geochemical behaviour of high-tech elements in the natural environment. Considering that the use of REE in high-tech products and processes is dramatically increasing, the results will also be important for policy-making.