Rare earth elements (REEs), known as “industrial vitamins”, are widely used in medical treatment, industry, agriculture, etc. However, with the increasing demand for REEs, excess REEs, such as gadolinium (Gd), are considered micropollutants in the environment. In this paper, the distributions of dissolved REEs were analyzed in three small streams, in order to determine the extent and occurrence of Gd anomalies. The shale-normalized REE patterns in the three streams were less smooth with heavy REEs higher than light REEs, for a weak reaction of the heavy REE complexes. A negative Ce (cerium) anomaly and positive samarium (Sm) and europium (Eu) anomalies were observed in the three streams and the negative Ce anomaly was affected by the pH of the alkaline rivers. However, a positive Gd anomaly was found in only a typical urban small stream, Jinzhong. With a population of approximately 60,000, Jinzhong runs by a hospital and through wastewater treatment plants (WWTPs). The concentrations of Gd in Jinzhong ranged from 1.54 to 86.65 ng/L with high anthropogenic Gd proportions (63.64%–98.07%). Anthropogenic Gd showed significant seasonal variations and distinct spatial disparities from upstream to downstream, and it was associated with certain ions such as Cl−. Anthropogenic Gd could be attributed to gadopentetic acid (Gd-DTPA), which is used in magnetic resonance imaging (MRI) in hospitals. This type of Gd was shown to be correlated with municipal wastewater. Due to the high stability and low particulate reactivity in water, anthropogenic Gd has great potential to serve as a tracer to prove the presence of medical wastewater.

Trace element pollution derived from human activities in aquatic systems has raised widespread concerns due to its toxicity, persistence, and bioaccumulation. In this article, we presented a systematic investigation of the anthropogenic overprints on trace elements geochemistry in three streams of the human-impacted (agriculture, urban area, and abandoned mining), located at Lake Aha, Guiyang, Southwest China. Concentrations reported in the study demonstrated that the abandoned mining stream showed the highest trace elements (608.16 μg/L), followed by the urban stream (566.11 μg/L) and agricultural stream (457.51 μg/L). Nonmetric multidimensional scaling (NMDS), used to display sampling dates and trace elements, showed discernible temporal variation in trace element concentrations. Trace element concentrations in months (May, September, and October) with less rainfall were higher than in June, July, and August indicated by NMDS. Principal component analysis (PCA) had shown that As, Ba, Mo, and Zn were mainly impacted by the urbanized streams, and Fe and Sr influenced by the mine. Risk assessment of human beings to trace elements demonstrated that As may pose a detrimental health risk. The research found that trace elements were potential tracers for the presence of human activities and environmental changes.

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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.