Gadolinium mobility in sediments: Environmental risk assessment

Gadolinium complexes has been widely applied as a contrast in medical magnetic resonance imaging, placing the ion under the target of emerging contaminants. Little is known about mobility and effects of Gd3+, and concentration anomalies have been reported for freshwater, indicating inefficiency of the sewage treat- ment system for removal. Hence, herein sorption and desorption of Gd3+ on riverbank and river bottom sediment samples from Southern Brazilian catch- ment were evaluated to state the ion environmental mobility and risk assessment. The samples showed a high maximum sorption capacity (25.27, 33.94, 17.67 and 12.75 meq kg −1 for SL1, SD1, SL2 and SD2, respectively), while there was a trend of mobilization of the contaminant into the liquid phase, especially for sandy samples. Mobilization factors ranged from 12.43 to 48.41%. Although there is a tendency of gadolinium to retain in riverbank and sediment, there is also a high tendency of mobilization to another environmental compartment, showing the importance of this kind of evaluation for further monitoring and remediation of environmental gadolinium contamination. Keywords: ion mobility, sorption, desorption, contamination risk, rare-earth element