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East China Sea (ECS), as the largest marginal shelf adjacent in the western North Pacific Ocean, is characterized by complicated ocean circulation, hypoxia, and a large input of terrigenous sediment. Sediments are important deposits of these information and may provide integrated information concerning seawater dynamics over a period of several years in estuary and continental shelf with high sedimentation rate. Rare earth elements (REEs) are widely used to trace sediment provenance, indicate particle-water interface and redox process. Three cores (Yellow Sea, C05; Southwest of Cheju Island; Minzhe Coast Current, ME3) were collected to be extracted with Tessier sequential extraction procedure to estimate the source of sediments and assess the environmental changes. Five fractions were studied: Exchangeable, Bound to carbonates, Bound to Fe–Mn oxides, Bound to organic matter, and Residues. The results showed that PAAS-normalized REEs patterns were remarkably different for various fractions. Carbonate and Fe-Mn oxides fractions exhibited middle REEs (MREE) enrichment in all cores. The organic fraction showed MREE and high REEs (HREE) enrichment. The residual fraction presented a relatively flat pattern. A big leap for carbonate, Fe-Mn oxides, organic fraction was observed in MT1, ME3, and their concentration increased with depth but no obvious difference for each chemical fraction was observed in C05. These results suggest that sedimentary environmental changes exert significant influences on the patterns and fractionations of REEs in the ECS. Ce anomaly in carbonate and Fe-Mn oxide fractions showed relatively small change in C05 while rapid increase (from 12 cm) in MT1, ME3, which possibly due to increase and source change of particle scavengers. Gd anomaly (1.11-1.15) in all chemical fractions showed positive anomaly, higher than background value (1.07±0.02) of quaternary sediment, implying anthropogenic effects during the sedimentary process. Thus, the fractionation among REEs could be used to trace various sources and sedimentary environment changes.Acknowledgement: This study was financially supported by the National Nature Science Foundation of China (No. 41276071, 41530965).