title: Anthropogenic rare earth elements and their spatial distributions in the Han River, South Korea.
abstract: Rare earth elements (REE) consist of lanthanides (from La to Lu), together with yttrium and scandium, in which anthropogenic REE, such as gadolinium (Gd), lanthanum (La), and samarium (Sm), has emerged as micro-contaminants in natural waters in highly developed countries. Here, we collected water samples in the Han River (HR) and its tributaries flowing through Seoul Capital Area, the world's second largest metropolitan area in order to examine how and to what extent anthropogenic REE anomalies may occur. Water samples show higher light REE concentrations than heavy REE concentrations, while wastewater treatment plant (WWTP) samples display much higher heavy REE concentrations due to high Gd concentration. The PAAS-normalized REE patterns indicate that WWTP samples display the pronounced positive Gd anomalies, in which anthropogenic Gd from magnetic resonance imaging (MRI) diagnostic system occurs as a form of Gd complexation with either Cl-or SO42-. Due to the WWTP, both the HR and tributaries show also positive Gd anomalies and the anthropogenic Gd concentrations increase as a function of the distance from the Paldang dam. This result indicates a positive correlation between populaton, number of MRI instruments, and positive Gd anomaly. Similarly, positive La and Sm anomalies exist in the HR, indicating that the HR is also affected by their point sources. Based on the discharge rate and anthropogenic REE concentrations, their fluxes are estimated to be 952 ± 319 kg/yr, suggesting that this amount of fluxes could disturb REE distribution in the Yellow Sea, and pose harmful effects on aquatic ecosystems.
authors.affiliation: Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea; Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea.
authors.forename: Hyeongseok
authors.initials: H
authors.lastname: Song
authors.affiliation: Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea.
authors.forename: Woo-Jin
authors.initials: WJ
authors.lastname: Shin
authors.affiliation: Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea; Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea. Electronic address: jongsikryu@gmail.com.
authors.forename: Jong-Sik
authors.initials: JS
authors.lastname: Ryu
authors.affiliation: Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea.
authors.forename: Hyung Seon
authors.initials: HS
authors.lastname: Shin
authors.affiliation: Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea.
authors.forename: Heesun
authors.initials: H
authors.lastname: Chung
authors.affiliation: Graduate School of Analytical Science and Technology, Chungnam National University, Daejeon 34134, Republic of Korea; Division of Earth and Environmental Sciences, Korea Basic Science Institute, Chungbuk 28119, Republic of Korea.
authors.forename: Kwang-Sik
authors.initials: KS
authors.lastname: Lee
mesh_terms: D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005682:Gadolinium / Q000032:analysis; D007811:Lanthanum / Q000032:analysis; D008674:Metals, Rare Earth / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D012493:Samarium / Q000032:analysis; D066106:Seoul; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D008674:Metals, Rare Earth; D014874:Water Pollutants, Chemical; D012493:Samarium; D007811:Lanthanum; D005682:Gadolinium
keywords: Gd anomaly; Han River; La and Sm anomalies; Magnetic resonance imaging; South Korea