Rare earth elements in the Rhine River, Germany: First case of anthropogenic lanthanum as a dissolved microcontaminant in the hydrosphere

► Strong anthropogenic La anomaly in Rhine River downstream of Worms, Germany. ► Point source of La related to production of fluid catalytic cracking catalysts. ► Effluent shows 49 mg/kg La, well-above levels that are ecotoxicologically effective. ► Rhine River also carries anthropogenic gadolinium (Gd) derived from contrast agents. ► In lower reaches of the river, >93% of total La and Gd are of anthropogenic origin.