Distribution of rare earth elements in sediment cores of Sabine-Neches Estuary

Abstract

Vertical profiles of several rare earth elements (REEs) were precisely measured in four dated sediment cores from the Sabine-Neches Estuary. From the extensive use of light rare earth elements (LREEs)—enriched zeolites during catalytic cracking process in nearby oil refineries, a significant enrichment of LREEs such as Lanthanum (La) was expected in sediment layers deposited in the estuary in the 1960s and 1970s. The measured concentrations of LREEs, and Fe normalized enrichment factors indicate that sediments are not enriched with light rare earth elements derived from effluents of oil refineries. The lack of strong enrichment of REEs and other trace metals and radionuclides are attributed to the strong binding of these constituents with dissolved organic matter found in high concentrations, and short hydraulic residence time, and/or due to the dilution of these metals by riverine soil particles.