Anthropogenic Gadolinium Accumulation and Rare Earth Element Anomalies of River Water from the Middle Reach of Yangtze River Basin, China

Abstract

Anthropogenic rare earth elements (REEs), such as gadolinium (Gd), lanthanum (La), and samarium (Sm), have emerged as microcontaminants in surface waters. In this study, surface water samples were collected from the middle Yangtze River basin from the metropolitan region of central China (Wuhan). We further evaluated the REE characteristics and anthropogenic Gd contribution. The total dissolved REE concentration in the river ranged as 6.76–99.31 ng L–1, the lowest value globally. Furthermore, the Post-Archean Australian Shale-normalized REE patterns, the negative anomaly of Ce, and the positive anomaly of Sm, Eu, and Gd indicated that heavy REE enrichment occurred in the water body. The anthropogenic Gd (Gdanth) concentration in Fuhe River and Hanjiang River was higher than that in the other rivers, with the difference ascribed to wastewater treatment plant (WWTP) discharges. The total daily discharges of Hanxi WWTP (HX-W) and Sanjintan WWTP (SJT-W) effluent were 53.5 and 13.5 g Gdanth, respectively. These values equate to 31.1 and 12.7 g Gdanth d–1 for HX-W and SJT-W per million people. Therefore, the quantitative evaluation of Gdanth in natural water near large cities warrants more attention.