Rare earth elements in the Yellow River estuary, China: Composition, distribution, and pollution insights.

Rare earth elements (REE) are emerging aquatic trace pollutants. A total of 191 sediment samples were analyzed from the Yellow River estuary to study the REE geochemical behavior and environmental impact. The results showed that the samples contained high REE levels, and the average total amount of REE was 195.28 μg/g. REE enrichment was prominent in northern and northeastern fine-grained sediment zones, less near the coast, and the enrichment level was correlated with sediment grain size and land-based influences. Although the REE content varied greatly among the sampling stations, the distribution patterns were similar. They all had a right-dipping negative slope pattern, were relatively enriched in the light rare earth elements (LREE), and were characterized by a V-type REE distribution pattern with an Eu deficit. Evaluation using Geoaccumulation Index (I), Contamination Factor (CF) and Pollution Load Index (PLI) showed that the sediments in the Yellow River estuary were generally in a state of slight REE pollution.