Uranium Contamination in Groundwater: Sources, Speciation, Transformations, Migration, and Remediation Strategies

Groundwater uranium contamination has emerged as a worldwide critical environmental and public health concern, demanding effective remediation strategies to protect water resources and ensure sustainable nuclear energy development in the context of global carbon neutrality. This comprehensive review systematically synthesizes current understanding of both natural and anthropogenic uranium sources, global distribution, regulatory standards, and associated health risks. The article critically analyzes uranium’s geochemical speciation, transformation pathways, and migration dynamics across varying hydrogeochemical conditions. State-of-the-art eco-friendly remediation technologies, including physicochemical treatments, permeable reactive barriers, microbial remediation, and phytoremediation, are critically reviewed with emphasis on their efficiency, applicability, and the long-term stability of uranium precipitates (particularly U(IV)). Finally, the review highlights key future research directions, such as (1) elucidation of uranium mineralization pathways, (2) optimization of microbial-assisted immobilization, (3) design of in situ remediation tailored to aquifer geochemistry, and (4) enhancement of the oxidative stability of biogenic U(IV) phases. Addressing these challenges will advance our predictive capability of uranium biogeochemistry in groundwater systems and bridge critical gaps between molecular microscopic mechanism and field-scale applications. Furthermore, this review provides a scientific foundation for optimizing the design of functional materials and promoting the development of green and low-carbon nanotechnologies.