Assessments of Dissolved Rare Earth Elements and Anthropogenic Gadolinium Concentrations in Different Processes of Wastewater Treatment Plant in Busan, Korea

초록

Gadolinium, commonly used as a contrast agent for magnetic resonance imaging (MRI), is discharged into aquatic environments without removal after treatment in wastewater treatment plants (WWTPs) because of its high stability. In this study, we collected water samples from Suyeong WWTP, Busan, to investigate the dissolved rare earth element (REE) removal capacity of each wastewater treatment process and to evaluate the discharge of anthropogenic Gd (Gd-anth) from effluents. As wastewater passed through each stage of treatment, the concentrations of light REEs (La-Eu) decreased, whereas those of heavy REEs (Tb-Lu) were relatively consistent. Negative Sm anomalies (<1) were observed in several samples, indicating that Sm can be removed by adsorption onto particles or phosphate during the biological removal process. Positive Gd anomalies (149 +/- 50, n=9) were observed in all samples. The ratios of Gdanth concentrations to measured Gd concentrations in all wastewater treatment processes were higher than 97%. This indicates that Gdanth was

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