Provenance discrimination of surface sediments using rare earth elements in the Yalu River estuary, China

Abstract

Rare earth elements (REE) are important tracers with which to explore sediment provenance. This study analyzed the distribution features of REE in surface sediments of the Yalu River estuary and determined their provenance. Estuarine systems of small rivers such as the Yalu River are suitable “target areas” to understand sediment transport and transfer processes. The fractional characteristics of REE distribution plots, La/Yb(UCC), Eu and Ce anomalies, La/Yb − ∑REE dendrograms, and discriminant functions can all be used for provenance discrimination of the surface sediments in the Yalu River estuary. All these indicate that REE can be one of the most important tools for the study of the coupling mechanism between the watershed and coast, either as a provenance tracer or as a signal of environmental change. The results from this study show that the middle and upper reaches of the Yalu River do not directly supply sediments to the estuarine delta. The western branch transported most material before the construction of the Shuifeng Reservoir in 1941, and these sediments have diffused to other sections via re-suspension. The Dayang River directly supplies sediments to the coasts of the northern Yellow Sea, which is transported toward land under the action of tidal currents or storm surges. These findings also reveal that anthropogenic activities have halted Yalu River estuarine delta preservation and dominated regional landform development in the last 100 years.