Gadolinium as an Emerging Contaminant: Environmental Cycling, Human and Plant Interactions, and Mitigation Strategies

ABSTRACT

Gadolinium (Gd) is a rare earth element whose anthropogenic cycle has expanded rapidly, driven primarily by the widespread medical use of gadolinium‐based contrast agents (GBCAs) in magnetic resonance imaging, alongside its use in selected electronic and energy‐related technologies. Because conventional wastewater treatment plants are largely inefficient at removing kinetically stable Gd chelates, GBCA‐derived Gd persists in effluents and propagates through coupled aquatic and terrestrial pathways. Evidence further indicates that gadolinium contamination can extend to drinking water distribution systems, highlighting exposure scenarios that are not confined to point‐source discharges. The environmental fate and biological effects of Gd are strongly controlled by speciation and ligand stability, including differences between linear and macrocyclic chelates that influence persistence, mobility, and bioavailability. This review synthesizes current knowledge on the environmental occurrence, distribution, and transport of Gd across aquatic and terrestrial systems, and evaluates speciation‐dependent interactions in humans and plants. In humans, attention is given to calcium‐related competition, potential dechelation and insoluble salt formation, and tissue retention, and to the conditions under which these processes may become relevant for human health risk assessment. In plants, we summarize root‐dominated accumulation, generally limited translocation, and concentration‐ and speciation‐dependent physiological responses, including oxidative stress signatures and nutrient‐uptake perturbations. We also assess remediation and recovery options spanning physical (membrane‐based separation), chemical (precipitation, ion exchange, and adsorption), and biological strategies (biosorption, bioaccumulation, rhizofiltration, biomineralization, and emerging protein‐based binders). Finally, key mechanistic and field‐relevant evidence gaps are delineated, and priorities are proposed for integrated monitoring, risk characterization, and mitigation of anthropogenic gadolinium across human–environment systems.