Discrimination of sediment provenance in the Yellow Sea: Secondary grain-size effect and REE proxy

Abstract

This study analyzed grain size and elemental concentrations (Al, Mg, Fe, and rare earth elements (REEs)) in 91 surface sediments to elucidate sediment provenance in the Yellow Sea. Elemental concentrations were normalized by Al concentration (C-element/C-Al) to minimize the sediment grain-size effect (GSE). However, noticeable linear relationships between AI concentration (or mean grain size) and the ratio (e.g., Mg/Al or Fe/Al) appeared unexpectedly in pair diagrams. The spatial distribution patterns of Fe/Al and Mg/Al ratios were also similar to the pattern of mean grain size. This implies that the GSE was not removed completely, even after the normalization process. Thus, great care must be taken when applying the ratios of C-element/C-Al as a proxy of sediment provenance. To improve provenance discrimination of the sediments in the Yellow Sea, the difference between the REE distribution patterns of Chinese and Korean river sediments, expressed as delta (delta = REE*(La) - REE*(Lu)), was calculated, and the spatial distribution patterns of the delta values were mapped. The delta values gradually increased from the western to the eastern part of the Yellow Sea, except for low delta values in the southeastern part of the Yellow Sea. This result indicates that the majority of Chinese and Korean river sediments are accumulating near to their respective coasts, except for a deposit along the southwestern coast of Korea in which a considerable amount of sediment from Chinese rivers has been accumulating. (C) 2016 Elsevier Ltd. All rights reserved.