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，在计算机断层扫描的造影剂中使用的人为钆（Gd）已被发现在世界各地的许多河流和初步样品从莱茵河甚至显示出强烈的人为富集镧（La）。La的来源尚不清楚，但与人为Gd一起，这种La化合物也在饮用水中观察到。在拟议项目期间，将研究莱茵河及其支流中稀土元素的分布。在随后的两个低排放和高排放期间，将确定流域地质，天然河流排放和人为输入对稀土元素分布的（季节性）影响，并将定位和表征未知La微污染物的来源。对沿着莱茵河的主要城市的饮用水进行研究将是对这项工作的补充。拟议的项目将提高我们对高科技元素在自然环境中的地球化学行为的理解。考虑到稀土元素在高科技产品和工艺中的使用正在急剧增加，其结果对政策制定也很重要。

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.