1. Occurrence, geochemical characteristics, enrichment, and ecological risks of rare earth elements in sediments of "the Yellow river−Estuary−bay" system.
- Author
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Liu, Ziyu, Gu, Xiang, Lian, Maoshan, Wang, Jing, Xin, Ming, Wang, Baodong, Ouyang, Wei, He, Mengchang, Liu, Xitao, and Lin, Chunye
- Subjects
RARE earth metals ,ESTUARINE sediments ,RIVER sediments ,SEDIMENTS ,CLAY minerals - Abstract
Recent studies have suggested that rare earth elements (REEs) are contaminants of emerging concern. Moreover, the understanding of the occurrence and risks of REEs in river-estuary-bay systems is limited. The present study investigated the distributions, geochemical characteristics, and ecological risks of Y and 14 REEs (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu) in sediments from the Yellow River to its estuary and adjacent Laizhou Bay. The average total concentrations of Y and REEs in the sediments generally increased from the Yellow River (149 mg/kg) to the estuary (165 mg/kg) and Laizhou Bay (173 mg/kg). In the estuarine core sediments, the concentrations of Y, light REEs (LREEs), and heavy REEs (HREEs) were in the ranges of 19.5–31.4 mg/kg, 58.6–156 mg/kg, and 12.3–19.1 mg/kg, respectively, from the 1700s to 2018, showing no obvious increasing or decreasing trends. The surface and core sediments from the river to the bay were characterized by obvious fractionation between LREEs and HREEs. In sediments, Fe minerals and clay are believed to promote the accumulation of REEs, especially HREEs. The enrichment levels of REEs generally increased from the middle reaches of the Yellow River to the bay, and Gd, Tb, Dy, Ho, Yb, and Lu were the most enriched elements in the sediments. Lu had moderate potential ecological risks in sediments of "the Yellow River−estuary−bay" system, and other REEs had relatively low ecological risks. The potential ecological risk indices of Y and REEs ranged from 78.7 to 144, showing increasing trends from the Yellow River to its estuary and adjacent bay, which should raise concerns regarding emerging contaminant management around estuarine and coastal regions. [Display omitted] • Concentrations of REEs increased from the Yellow River to estuary and Laizhou Bay. • Historical REE contents (1707–2018) of the estuarine sediment core were determined. • Fe minerals and clay promoted the REE accumulation in sediments. • Gd, Tb, Dy, Ho, Yb, and Lu were most enriched elements in the sediments. • Moderate ecological risks of REEs appeared and increased from the river to bay. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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