Rare Earth Element Compositions And Their Implications For Material Sources In The Sediments Of Yalu Estuary And Its Coastal Waters

Estuary is a hinge that connects the river and the ocean, and is also the main place of material exchange between land and sea. As the important marginal sea in the west Pacific Ocean, Yellow Sea, characterized by rapid sedimentary rate and high resolution and massive terrigenous clastic material in the sediments, is an ideal palce for studying the interactions between land and sea. Yalu River is an important river of North Yellow Sea, and exerts obviously impact to the deposition of the Yellow Sea region. As the same time, there are several rivers of Korean Peninsula which carry huge sediments into the Yellow Sea. Yangtze River, Yellow River also have far implications to the Yellow Sea sediments because of their huge sediments. So the material sources in this region is very complicated. Comprehending the different sediment sources on the contribution of the North Yellow Sea could deepen the understanding of the process of material recycling of Yalu River Estuary and provide scientific basis for water environment protection, pollutant treatment, marine resources development, ports and waterways mangement and coastal protection in this region.In this paper, surface sediments and sediments core CH01 were collected in the Yalu River Estuary and its adjacent sea areas. Subsequently, these samples were analyzed for rare earth element (REE) compositions and grain size parameters. The purpose of this paper is to:(1) study the distrubutions of REE compositions in the surface and coral sediments; (2) discriminate the main controlling factors of REE distrubutions; (3) compare the REE compositions between the sediments of Yalu River estuary and Yangtze River, Yellow River and the main rivers on the Korean Peninsula; (4) discuss their implications for sediment sources of this study area.The results indicate that, the average REE content in the sediments of Yalu River Estuary and its adjacent sea area, which is similar that of the global average content and relatively closed to the REE content of Chinese loess, is greatly different from the REE abundance of deep-sea sediments, and display the feature of "pro-land". In addition, the sediments of the study area is inclined to typical terrigenous, characterized by enriched lighter rare earth element and deficit heavier rare earth element, as well as significant negative Eu anomalies under Chondrite-normalized REE patterns. Comparing with the REE composition among the study area and the surrounding major river sediments, the REE composition of the sediments in China are obviously different from that of the Korean Peninsula, suggesting thar the distribution patterns of REE are mainly controlled by source rock. Furthermore, the REE differentiation characteristics parameters of the sediment core are significant distinct from that of Yangtze River, Yellow River of China, Han River, Keum River, Yeongsan River of Korean Peninsula, and more close to that of Yalu River sediments. The discriminant function DF can also demonstrate that the source of Yalu River Estuary sediments are mainly from terrigenous clastic material. Moreover, the largest contribution of sediments transport to the North Yellow Sea.