Rare Earth Elements Geochemistry and Provenance Discrimination of Sediments in Tolo Harbour, Hong Kong

Abstract

Rare earth elements (REE) concentrations have been analyzed in 13 sediment samples from Tolo Harbour. The highest concentrations of P REE, P LREE (light rare earth elements) and P HREE (heavy rare earth elements) are all at site G as the enrichment of Mn-Fe oxyhydroxides and the highest pH of site G relative to its nearby areas. The relatively higher P LREE= P HREE ratio at site G is probably due to the stronger REE fractionation. During the fractionation process, LREE are preferentially scavenged on particle surfaces such as Mn-Fe oxyhydroxides and clay minerals. Concentrations of P REE, P LREE and P HREE at sites Y and Z are much lower than those at other sites as calcareous biological debris dilute the REE abundances of the sediments in Tolo Harbour. REE are released from sediments into waters due to the high salinity in Tolo Harbour and REE fractionation occurs in this release process. The provenance of sediments in Tolo Harbour is terrigenous and the North American shale composite (NASC)-normalized REE patterns of the 13 samples in Tolo Harbour all display strongly negative Eu anomalies. P REE is poorly correlated with Zr and Hf, which suggests that Tolo Harbour is heavily polluted by human activities.

The procurement and use of knappable glassy volcanic raw material from the late Pleistocene Pilauco site, Chilean Northwestern Patagonia

“…Geochemical analyses were carried out at the University of Colorado, Boulder. The selected samples were ground to a fine powder and dissolved by acid digestion (Chen, Yang, & Jiao, ). Samples were analyzed for trace elements by using an ELAN® dynamic reaction cell TM ‐e (ELAN DCR‐E) inductively coupled plasma mass spectrometer.…”

Importance of the Spatial Distribution of Rare Earth Elements in the Bottom Sediments of Reservoirs as a Potential Proxy for Tracing Sediments Sources. A Case Study in the Dominican Republic

“…The geochemical mobility of REE from those rocks is enhanced by the high precipitation rate and temperature, resulting in high weathering and leaching rates and hydraulic sorting processes [3]. While LREE preferentially occur as free species and are more strongly retained, HREE are more mobile and leachable from the rocks, forming easily soluble complexes with, e.g., amorphous Fe-Mn oxides, organic matter, and carbonates in the weathered environment [22,52], which may explain the moderate HREE increase in these soils. The enrichment in HREE can also be explained by the relationship between the pH values of soils and the concentration of REE.…”

“…Given the drawbacks of identifying sediment sources from REE, their distribution, geochemical properties, and fractionation patterns are important tools for understanding the mechanisms by which REE accumulate in lake sediments, and thus identifying their origin or nature [13,20,22,23].…”

Petrographic and geochemical analyses of dune sands from southeastern Mexico, Oaxaca, Mexico

“…Furthermore, the REE results indicate a significant control of granitic rocks in the compositional framework of the dune sands of SE Mexico as supported by the presence of a large amount of monocrystalline quartz with straight extinction and K-feldspar. The LREE/HRRE ratio of 4.15 suggests little fractionation of the western and eastern dune sands attributed to the absence of minerals like monazite and allanite that increases the concentration of LREE in the sediments (Armstrong-Altrin, 2020; Chen, Yang, & Jiao, 2015;Gromet & Silver, 1983;Wang & Liang, 2015).…”