Distribution and origination of rare earth elements in surface sediments of the Bohai Strait

To understand the material exchange between the Yellow Sea and the Bohai Sea, the distribution and origination of rare earth elements (REE) in surface sediments from 383 stations in the Bohai Strait were studied, the influencing factors, main sources of materials, and migration mechanisms of the REE were analyzed systematically. Results indicate that the total REE content (∑REE) in the sediments of the Bohai Strait ranges from 44.85 to 283.00 μg/g, on average o of 166.33 μg/g. The high-value areas were distributed in mainly the western and southern sea areas with finer sediments, while the low-value areas were located in the northeastern sea areas with coarser sediments, showing characteristics of light REE enrichment and heavy REE depletion. Correlation analysis between ∑REE and certain characteristic parameters to grain size, chemical index of alteration (CIA), and some elements, we found that ∑REE is positively correlated with sediment mean grain size, indicating a close relationship between REE distribution and sediment grain size / provenance. The distribution patterns of REEs in the upper continental crust and chondritic meteorites in the Bohai Strait show similarities with the material carried by the Huanghe (Yellow) River and rivers surrounding the Liaodong Bay, indicating a distinct terrigenous imprint of riverine materials. In contrast, there are significant differences with the Yalu River and rivers in the Korean Peninsula, indicating that the primary source of the material is from the Chinese mainland. Using the standardized calculation of δEu-(La/Yb)_N and (Gd/Yb)N-(La/Yb)_N indices based on chondritic meteorites, source discrimination was conducted. The results indicate that the material in the Bohai Strait mainly originates from the Huanghe River, while in the northeastern sea areas of the Bohai Strait, it is a mixture of the Huanghe River and rivers surrounding the Liaodong Bay. The combined effect of Liaodong Bay circulation and Bohai Sea coastal current affects the sedimentary patterns in the Bohai Strait.