Rare Earth Element Compositions Research Articles

Development of rare earth element-based hybrid aluminium composites using stir casting process.

Aerospace and marine industries are constantly in search of materials that can provide good strength and durability while also being lightweight. Aluminium composites with adequate reinforcements have been proven to be effective in achieving incredible mechanical properties while also maintaining a good strength to weight ratio. Numerous studies have been done to study the various possibilities of matrix reinforcement combinations in aluminium composites. This work focuses on studying the effect of varying Cerium Oxide (CeO2) percentage in the aluminium composite on its tensile strength, hardness and corrosion resistance. CeO2 is used along with Silicon Carbide (SiC) and Multi-Walled Carbon Nanotubes (MWCNT) to develop four samples of hybrid aluminium composites with SiC and MWCNT constituting 1% and 0.1% of the composite and the weight percentage of CeO2 is varied between 1 and 2.5%. All the samples were fabricated using the modified stir casting process. The results show that the hardness and tensile strength of the composites peak when the CeO2% is at 2% while corrosion resistance only gets better with increasing reinforcement content. A significant enhancement in mechanical and physical properties of aluminium composite suggests that MWCNT is an effective hybridizing agent with SiC and CeO2 to develop aluminium composites.

Substantial trace metal input from the 2022 Hunga Tonga-Hunga Ha’apai eruption into the South Pacific

The January 2022 eruption of the Hunga Tonga-Hunga Ha’apai (HTHH) volcano discharged 2,900 teragrams of ejecta, most of which was deposited in the South Pacific Ocean. Here we investigate its impact on the biogeochemistry of the South Pacific Gyre (SPG) using samples collected during the GEOTRACES cruise GP21 in February-April 2022. Surface water neodymium isotopes and rare earth element compositions showed a marked volcanic impact in the western SPG, potentially extending to the eastern region. Increasing trace metal concentrations in surface waters and chlorophyll-a inventories in euphotic layers between the eastern and western SPG further suggest that the volcanic eruption supplied (micro)nutrients potentially stimulating a biological response. We estimate that the HTHH eruption released up to 0.16 kt of neodymium and 32 kt of iron into the SPG, which is comparable to the annual global dust-borne Nd flux and the annual dust-borne Fe flux to the entire SPG, respectively.

Preparation, characterization and emission of Na3-3xLnxFe2(PO4)3 (Ln = Eu, Tb; 0 ≤ x ≤ 0.1 mol %) and photocatalytic activity of Na3Fe2(PO4)3

Rare earth doped compositions Na3-3xLnxFe2(PO4)3 (x = 0, 0.025, 0.05, 0.075 and 0.1) were prepared by ion-exchange method using Na3Fe2(PO4)3 and LnCl3 (Ln = Eu and Tb). Pristine Na3Fe2(PO4)3 was obtained by ethylene glycol assisted gel burning procedure. The phase characterization was performed by powder X-ray diffraction (XRD). All the compositions were well crystalized in monoclinic lattice. The FE-SEM images and elemental mapping were obtained. The infrared and Raman profiles of all-compounds were dominated by the bands owing to the (PO4) units. Investigation on photoluminescence emission and excitation spectra of Ln3+ (Ln = Eu, Tb) were carried out. The excitation spectra of Na3-3xLnxFe2(PO4)3 (Ln = Eu and Tb) gave intensive band at 256 (370) nm for Eu (Tb) doped phosphors. The photoluminescence emission spectra of Ln3+ (Ln = Eu, Tb) were carried out. The emission spectra of these composition were characterized by f -f transitions corresponding to 613 (5D0→7F2) for Eu and 543 (5D4→7F5) for Tb doped compositions. The maximum emission intensity for Eu (Tb) doped phosphors was found at x = 0.075 (0.05). The analysis of CIE and CCT values of all prepared phosphors were also carried out. Decay curves were analyzed in detail. The visible-light photo-catalytic activity of parent Na3Fe2(PO4)3 was examined against decomposition of methylene blue and methyl orange dyes. Parent Na3Fe2(PO4)3 exhibits good efficiency against MB (≈94.5 %) and moderate efficiency against MO (≈64 %) in 180 min of visible light irradiation. Scavengers’ experiments were carried to identify the active species during photodegradation.

Study on Production Characteristics and Change in Production Location of Pottery Excavated from DongOe-dong Site in Goseong

As a result of scientific analysis of 26 pottery excavated from the DongOe-dong site in Goseong, pottery with various firing degrees was confirmed, ranging from low-firing pottery with mica minerals detected to high-firing pottery with high-temperature minerals such as cristobalite and mullite detected. In addition, low-firing pottery has an absorption rate of 9.7∼25.8% and generally shows high saturation value. On the other hand, high-firing pottery has low absorption rate and saturation value, so the physical characteristics of the pottery show a high correlation with the group classified by XRD analysis. Pottery with a low firing degree commonly contains fine-grained mineral particles and has a similar composition of trace elements such as Rb, Ba, and Sr. And they were most abundantly excavated from the No. 1-1 moat. However it was confirmed that there is a difference in the production area because compositions of the rare earth elements are distributed in two areas in the graph. High&intermediate-firing pottery samples are observed to have a vitrified base matrix and relatively less temper minerals. And their contents of Rb, Sr, and Ba are significantly different from low-firing pottery. In the composition of rare earth elements, they are all distributed in same area as one of the separated areas of low-firing pottery, so it is highly likely these pottery were produced in the same or nearby production region regardless of the firing degree. As a result of checking up the composition of rare earth elements according to the archaeological chronology of pottery, it is estimated that there was a change in the production region of the pottery introduced into the DongOe-dong site around 250 AD.

Coupled role of climate and tectonics in the deposition of the late Quaternary sedimentary sequence in the southern margin of the central Ganga Plain, India

ABSTRACT The Ganga Plain’s sedimentation is primarily controlled by Himalayan tectonics, variations in monsoon intensity, and glacier size. However, the significance of intrabasinal tectonics, which is an interplay of the Himalaya tectonics and basement tectonic configuration of the Ganga Plain, in comprehending the late Quaternary Ganga Plain sedimentation remains unclear. In this study, the sediment provenance and extent of weathering experienced by the sediments are studied using the mineralogical and geochemical (major, trace, and rare earth elements) composition of a sedimentary cliff sequence exposed at the Ramnagar locality near the cratonic peripheral bulge in the southern Ganga Plain. In the Ramnagar cliff sediment section, two sediment packages, designated SP-A and SP-B, are identified based on mineralogy, texture, and geochemistry. These packages of sediments show mild chemical weathering and distinct geochemical compositions. The lower part (SP-A) of the Ramnagar cliff section is characterized by higher contributions from mafic sources (pyroxene, feldspar, and mica as dominant minerals), while the upper part (SP-B) is predominately derived from felsic sources (mica and feldspar as dominant minerals), which are supplied via the peninsular and the Himalayan rivers, respectively. The southern part of the central Ganga Plain shows evidence of a shift in the sediment provenance from mafic to felsic source rock at 40 ka. This study demonstrates how weathering and sedimentation are controlled by both regional tectonics and climate in the southern margin of the central Ganga Plain.

Separation and utilization of iron, cerium, and other rare earth elements from rare earth waste by chlorination

Due to the lack of effective screening systems in the rare earth waste recycling industry, the composition of rare earth elements in rare earth waste is complex and difficult to separate. In response to such problems, by studying the reaction behavior between various elements in rare earth waste and cobalt chloride, we propose a process path for the separation and recovery of iron, cerium and other rare earth elements using cobalt chloride roasting. The experiments on simulated wastes show that the leaching rates of the Nd, Sm, Gd, Pr can reach 98.31%, 94.5%, 93.87% and 72.05% under the optimal process conditions, respectively. Ce and iron remain in the leaching residue in the form of CeO2 and CoFe2O4, respectively. And through a simple magnetic separation process, CeO2 and CoFe2O4 can be enriched in non-magnetic leaching residue and magnetic leaching residue, respectively. The cerium content in the leaching residue composed of cobalt ferrite is only 1.95%. Therefore, this method is beneficial to the separation and high-value utilization of iron, cerium, and other rare earth elements in the waste system. The research results can provide theoretical reference for the low-cost and high-value recovery of rare earth secondary resources.

The Palaeo-Productivity Signals Chronicled from the Buxa Formation, North-East Lesser Himalaya, India

ABSTRACT The Mesoproterozoic era is known for its relatively stable ecological conditions and limited atmospheric oxygen. Despite this understanding, uncertainties remain about how ocean chemistry evolved during this time and its potential impact on the development of complex eukaryotic life forms. In response to these uncertainties; we have undertaken a study to investigate indicators of ancient productivity within the Buxa Formation of the Lesser Himalaya in Sikkim. By analyzing the isotopic values ( δ13 C and δ 18Ο values) as well as Rare Earth Element (REE) composition, a total n = 151 carbonate samples were investigated across three sections of the Buxa Formation: Jorethang to Mangalbare, Legship to Naya Bazar, and Reshi to Mangalbare, Sikkim. The study’s findings show that there was minimal variation in δ13C values, consistently ranging between –0.5 and +2.5 ‰ VPDB. This pattern suggests a relatively steady and moderately high level of productivity during that time. This productivity might have been influenced by a temporary increase in atmospheric oxygen levels. Additionally, we have also reviewed and examined stromatolites as part of the investigation.

Origin of porosity in evaporite platform dolostone in the middle Cambrian Shaelek Formation, NW Tarim Basin, China: constraints from petrology, mineralogy and geochemistry

The extensive middle Cambrian evaporite platform dolostone represents a significant area for hydrocarbon exploration in the Tarim Basin with recent advances indicating promising exploration prospects. However, owing to its considerable depth and the limited exploration, the genesis and distribution of evaporite-related dolostone reservoirs from the middle Cambrian remain poorly understood. This study includes detailed field investigations along with petrological, mineralogical and geochemical analyses to characterise the secondary porosity of the middle Cambrian Shaelek Formation evaporite platform dolostone and to explore the origin of the diagenetic fluids responsible for these features. The results show that gypsum dissolution vugs are the main secondary porosity in the evaporite platform dolostone reservoirs, with their development and distribution strongly controlled by sedimentary facies. Meteoric dissolution during the penecontemporaneous period is responsible for this secondary porosity. The frequent fluctuation in sea-levels and the transient exposure of the dolostone reservoirs provide favourable conditions for the dissolution of unstable gypsum. The multiple stages of calcite filling in the vugs result from supersaturated precipitation from fluids during the late stage of meteoric diagenesis. Variations in δ13C, δ18O and rare earth element compositions between the two types of calcite reflect different stages of fluid evolution and varying degrees of water–rock reaction. The vug-filling fluorite is of non-hydrothermal genesis but results from the highly evaporative concentrated seawater and terrigenous input. The highly concentrated F– in evaporative seawater, combined with F– from fluvial input (if any) during subaerial exposure, most likely provides the F– necessary for fluorite precipitation. A model of reservoir formation and evolution has been established that will be beneficial for hydrocarbon exploration and prediction of the deeply buried Cambrian evaporite platform dolostone reservoir.

In Situ High-Pressure Correlated Transportation of Heavy Rare-Earth Perovskite Nickelates as Batch Synthesized within Eutectic Molten Salts at MPa-pO2.

The multiple magneto-/electrical quantum transitions discovered with d-band correlated metastable perovskite oxides, such as rare-earth nickelate (ReNiO3), enable applications in artificial intelligence and multifunctional sensors. Nevertheless, to date such investigation merely focuses on ReNiO3 with light or middle rare-earth composition, while the analogous explorations toward heavy rare-earth (ReHNiO3, ReH after Gd) are impeded by their ineffective material synthesis relying on GPa pressure. Herein, for the first time we synthesized the powder of ReHNiO3 in grams/batch with ∼1000 times lower pressure and ∼300 °C lower temperature in comparison to the previous ∼101 milligram/batch results, assisted by their eutectic precipitation and heterogeneous growth within alkali-metal halide molten salt at MPa oxygen pressures. Further in situ characterizations under high pressures within a diamond anvil cell reveal a distinguishing pressure predominated bad metal transport within the nonequilibrium state of ReHNiO3 showing high-pressure sensitivity up to 10 GPa, and the temperature dependences in electrical transportations are effectively frozen.

Migmatite-Gneiss-Granite Basement of Southwestern Nigeria: Mineralogical and Geochemical Evidence for a Possible Common Ancient Protolith

Nigeria occupies southern section of the Pan-African orogenic belt and migmatite-gneiss-granite terrain forms a major component of its basement complex. Field geology, optical mineralogy and geochemical study of this rock unit in Idanre area, SW Nigeria were undertaken with a view to characterize them, elucidate their tectonic significance, and determine their origin. Major, trace and Rare Earth Elements (REE) composition were determined by XRF and ICP-MS techniques respectively in Bureau Veritas, Vancouver, Canada.

Plagioclase Megacrysts in Mesoproterozoic Amphibolites from the New Jersey Highlands, USA: Indicators of Mixed-Source Magma and Fractionation Interruption in Anorthosite-Dominated Terrains

Rare amphibolite in the New Jersey Highlands containing plagioclase megacrysts ≤13 cm long forms bodies 0.5 to 2 m thick that preserve a penetrative metamorphic fabric and have sharp, conformable contacts against Mesoproterozoic country rocks. The megacrystic amphibolites were emplaced as thin dikes along extensional faults between 1160 and 1130 Ma. Amphibolites contain weakly zoned, subhedral andesine megacrysts (An29–44) in a matrix of plagioclase (An18–38), magnesio-hastingsite, biotite, diopside, Fe-Ti oxides, and apatite. The whole-rock major oxide composition of the megacrystic amphibolite matrix has high TiO2 (2.07 wt.% ± 2.0%), Al2O3 (17.03 wt.% ± 0.87%), and Fe2O3t (12.84 wt.% ± 3.2%) that represents an Al-Fe-rich mafic magma type that is characteristic of anorthosite associations globally. The whole-rock, rare earth element (REE) composition of the megacrystic amphibolite matrix is characterized by enrichments in light rare earth elements (LREEs) (La/YbN = 1.73–10.69) relative to middle (MREEs) and heavy (HREEs) rare earth elements (Gd/YbN = 1.30–1.85), and most samples have small positive Eu anomalies (Eu/Eu* = 0.95–1.25). The megacrystic amphibolite matrix is also enriched in large ion lithophile elements (LILEs) and depleted in high field strength elements (HFSEs) (e.g., Ba/Nb = 24–22). Megacrystic amphibolites formed through partial melting of subduction-modified lithospheric mantle that fractionated olivine and plagioclase, producing a high-Al-Fe mafic magma. Plagioclase megacrysts formed through extraction of a plagioclase-rich crystal-liquid mush from anorthosite that mixed with mafic magma and collected in the upper part of the mid-crustal magma (depth of ~20 km based on Al-in-hornblende geobarometry) chamber through flotation. Periodic tapping of this mixed source by extensional fractures led to emplacement of the amphibolites as dikes and may have interrupted the extensive fractionation and plagioclase separation necessary to form voluminous anorthosite intrusions.

Rare earth elements as a tool to study the foliar nutrient uptake phenomenon under ambient and elevated atmospheric CO2 concentration

The ability of plants to uptake nutrients from mineral dust lying on their foliage may prove to be an important mechanism by which plants will cope with increasing CO2 levels in the atmosphere. This mechanism had only recently been reported and was shown to compensate for the projected dilution in plants ionome. However, this phenomenon has yet to be thoroughly studied, particularly in terms of the expected trends under different dust types and varying atmospheric CO2 concentrations, as projected by the IPCC. We treated plants grown under ambient (415 ppm) and elevated CO2 (850 ppm) conditions with either desert dust, volcanic ash, and fire ash analogues by applying it solely on plant foliage and studied their Rare Earth Elements concentrations and patterns. The Rare Earth Elements compositions of the treated plants originated from the dust application, and their incorporation into the plants led to a significant increase in plants vitality, evident in increased photosynthetic activity and biomass. Two trends in the foliar nutrient uptake mechanism were revealed by the Rare Earth Elements, one is that different treatments affected the plant in decreasing order volcanic ash > desert dust > fire ash. The second trend is that foliar intake becomes more significant under elevated CO2, an observation not previously seen. This testifies that the use of Rare Earth Elements in the study of foliar nutrient uptake, and other biological mechanisms is fundamental, and that foliar pathways of nutrient uptake will indeed become more dominant with increasing CO2 under expected atmospheric changes.

Data Fusion of Acoustic and Optical Emission from Laser-Induced Plasma for In Situ Measurement of Rare Earth Elements in Molten LiCl-KCl.

Molten salts have a significant potential for use as next-generation nuclear reactor coolants and in pyroprocessing for the recycling of used nuclear fuel. However, the molten salt composition needs to be known at all times, and high temperatures and intense ionizing radiation pose challenges for the monitoring instrumentation. Although the technique of laser-induced breakdown spectroscopy (LIBS) has been studied for in situ measurements of molten salts, trials to improve its monitoring accuracy using chemometrics are lacking. In this study, a data fusion technique using the LIBS optical and laser-induced acoustic (LIA) signals was investigated to enhance the measurement accuracy for molten salt monitoring. Prediction models were constructed using the partial least-squares method, and the variable importance in projection scores was analyzed to evaluate the effect of incorporating the LIA signal into the analysis. This study investigates rare earth elements Eu, Er, and Pr found not only in nuclear but also in other settings such as laser and magnetic materials. The analysis of LIBS data without data fusion resulted in a root-mean-square error of prediction (RMSEP) of 0.0774-0.0913 wt %, whereas the prediction model using data fusion led to approximately 18-40% enhanced RMSEP (0.0461-0.0679 wt %). The results suggest that fusing the LIBS data with the simultaneously recorded LIA data can improve the monitoring accuracy of rare earth element composition in molten salts.

Rare earth element enrichment process of bioapatite in deep-sea REY-rich sediments

Rare earth element and yttrium (REY) compositions of bioapatite (e.g., fish tooth and bone) can serve as potential paleoceanographic indicators. However, the REY enrichment of bioapatite and REY transfer from FeMn micronodule to bioapatite remain unclear owing to a lack of comparative study on these processes under variable redox conditions (oxic vs. suboxic), which hampers the utility of these indicators. To address these uncertainties, we conducted in situ geochemical analyses of fish teeth and FeMn micronodules from two REY-rich sediment cores (GC01 and GC02) collected from the Clarion–Clipperton fracture zone in the central equatorial Pacific. We found that the Ce/Ce* ratios of fish teeth from GC01 (sediments ΣREY = 723 ± 274 ppm) and GC02 (sediments ΣREY = 506 ± 65 ppm) gradually increased with depth under oxic conditions, with calculated oxic pore water-derived REY increasing from ∼0–3% on the surface to ∼11–24% at 200 cmbsf. In deep sediment columns (>200 cmbsf), the suboxic pore water contributed a small amount of REY (∼4% to ∼13%) to fish teeth, as evidenced by sharp increases in Ce/Ce* ratios of fish teeth and decreases in Ce/Ce* ratios and increases in YN/HoN ratios of micronodules. Therefore, the REY-patterns of fish teeth in core-deep samples were overprinted by oxic–suboxic pore waters may be unreliable archives of ancient bottom seawater.

"Nanoscale electric vehicle" for the patterning of nanomaterials: Selective electrophoretic deposition of programmable silica composite nanoparticles

Colloidal nanocrystals stand at the forefront of various applications given their unique optoelectronic properties and abundant active sites. However, the surface dynamics of nanocrystals make it difficult to avoid performance sacrifices that result from certain processing methods. Here we introduce a general nanoscale electric vehicle (NEV) platform for efficient and lossless manipulation and processing of functional nanomaterials by selective electrophoretic deposition. Dual-ligand modified system comprising charging ligands and anchoring ligands enables NEV to be universally compatible with fine patterning of various nanomaterials such as quantum dots, perovskites, rare-earth compositions or Janus materials. Without performance impairment from additional modifications, the luminescence performance of the nanocrystals improved significantly with the help of NEV to a level comparable to the commercial standard. Furthermore, we demonstrate the capabilities of our approach for display and anti-counterfeiting encryption applications. Our strategy offers a versatile way of creating high-performance nanomaterial devices in a cost-effective and non-destructive manner.

Geochemistry of carbonate microbialites through time and space: Insights from the microbialite collection of the Muséum National d'Histoire Naturelle (MNHN), France

Microbialites are microbial sedimentary structures that constitute some of the oldest traces of life on Earth. By their deposition in a wide range of sedimentary environments and their presence throughout most of geological time, the sedimentological and geochemical signatures they preserve represent important paleoenvironmental archives for understanding Earth's biological and geochemical co-evolution. Here we present a large microbialite collection containing >1370 curated specimens, covering all continents except Antarctica and spanning >3.5 Ga of Earth history, that is accessible to the international scientific community for examination and sampling at the Muséum National d'Histoire Naturelle (MNHN) in Paris, France. After cataloguing and evaluating the samples for their lithology, biogenicity, and inferred depositional environments, we characterized the collection for selected geochemical parameters, notably carbonate stable carbon and oxygen isotope ratios, as well as major, trace, and rare earth element compositions. Finally, we explore the different geochemical proxies analyzed with regards to their utility for reconstructing evolving Earth surface environments and/or microbial metabolisms via comparison of geochemical data from the MNHN Microbialite Collection to a compilation of similar proxy data for carbonates worldwide. We demonstrate that certain temporal trends previously recognized in carbonates worldwide (e.g., with respect to variations in C and O stable isotope compositions and redox sensitive trace element enrichments) are well reflected in this collection. Our findings highlight the utility of the MNHN Microbialite Collection and microbialites more generally for reconstructing the conditions associated with habitable environments in deep time and for tracing the response of microbial communities to the geochemical evolution of Earth's surface.

Er-Doped BiVO4/BiFeO3 Nanocomposites Synthesized via Sonochemical Process and Their Piezo-Photocatalytic Application.

In this work, Er-doped BiVO4/BiFeO3 composites are prepared using the sonochemical process with a difference of rare earth loading compositions. The crystallinity and chemical and morphological structure of as-synthesized samples were investigated via X-ray diffraction, Raman scattering, and electron microscopy, respectively. The diffuse reflectance technique was used to extract the optical property and calculate the optical band gap of the composite sample. The piezo-photocatalytic performance was evaluated according to the decomposition of a Rhodamine B organic compound. The decomposition of the organic compound was achieved under ultrasonic bath irradiation combined with light exposure. The Er-doped BiVO4/BiFeO3 composite heterojunction material exhibited significant enhancement of the piezo-photocatalytic activity under both ultrasonic and light irradiation due to the improvement in charge generation and separation. The result indicates that Er dopant strongly affects the phase transformation, change in morphology, and alternation in optical band gap of the BiVO4 matrix. The incorporation of BiFeO3 in the composite form with BiVO4 doped with 1%Er can improve the photocatalytic performance of BiVO4 via piezo-induced charge separation and charge recombination retardment.

Provenance constraints on the Late Triassic ejecta layer from Churchwood Quarry, SW England: An impactite suite from Manicouagan

AbstractIn situ LA‐ICP‐MS/MS U‐Pb and Rb‐Sr geochronology combined with geochemical analysis and electron microscopy have been performed on ejecta components sampled from the Mid‐to‐Late Triassic Mercia Mudstone Group at Churchwood Quarry, SW England. The layer comprises altered impact spherules, melt‐rich and fragment‐rich accreted grain clusters (AGCs), along with shocked mineral phases. Late Triassic ages are obtained: a U‐Pb age of 219 ± 72 Ma from variably shock‐metamorphosed apatite and a Rb‐Sr age of 213 ± 31 Ma from melt‐rich AGCs. A post‐depositional U‐Pb age of 200 ± 7.5 Ma obtained from the carbonate host matrix correlates with an early Jurassic dolomitization event associated with regional marine transgression. Several links to the Manicouagan impact structure, Canada, are identified that complement previous provenance studies: (1) rare earth element compositions of impact spherules and melt‐rich AGCs match those of the Manicouagan impact melt sheet; (2) the preservation of Archean and Paleo‐ to Neoproterozoic target rock U‐Pb ages in zircon and apatite match those recorded within Manicouagan basement lithologies; and (3) impact spherules and melt‐rich AGCs record initial 87Sr/86Sr compositions that overlap with those of the Manicouagan impact melt sheet and the target rocks involved in their generation.

Rare Earth Elements in Shells of Black Sea Molluscs: Anomalies and Biogeochemical Implications

Rare earth elements (REE) are a class of increasingly used high-tech product components and new emerging environmental pollutants, which are accumulated, in particular, in marine biota. In this study, REE contents were estimated in shells of several molluscs common in the Black Sea. The summed REE contents in mollusc shells decreased in the following order of species: Magallana gigas = Anadara kagoshimensis > Flexopecten glaber ponticus ≥ Rapana venosa > Mytilus galloprovincialis, ranging from 0.46 to 1.9 mg·kg−1. Canonical analysis of principal coordinates allowed for the correct identification of species based on the REE composition in no fewer than 67% of the samples. The mollusc shells were anomalously enriched in Sc, Y, La, Eu and Tb, most likely due to anthropogenic contamination. The Y/Ho ratios in all samples were represented by two fit values: 23.2 (chondritic) and 67.6 (superchondritic, mainly associated with A. kagoshimensis). A new universal relationship linking the contents of three light and heavy REE in Black Sea mollusc shells was proposed: Ce0.3 Er0.7/Yb = 2.00 ± 0.46 (mean ± standard deviation).

East Asian monsoon and westerly jet driven changes in climate and surface conditions in the NE drylands of China since the Late Pleistocene

The East Asian summer monsoon (EASM) is a major component of the global climate yet, the causes for the past spatiotemporal variability of EASM rainfall, its interactions and impacts remain unresolved. Here we use the Sr–Nd isotopes and rare earth elements composition of dust in a peat record from northeast (NE) China to investigate the relationship between aeolian dust, the East Asian monsoon and Westerly Jet (WJ) over East Asia since the Late Pleistocene (14 cal ka BP). The NE drylands of China dominate the dust fraction (Hunshandake, Horqin; 44–88%) with a contribution from the deserts of NW China (Badain Jaran, Tengger, Taklamakan; 10–44%), suggesting an influence of the WJ. Dust deposition varied during the Holocene, displaying a minimum between 8.0 and 6.0 cal ka BP and two peaks at 5.8–3.8 and 1.7–0.3 cal ka BP. Changes in dust flux are opposite to the East Asian winter monsoon intensity profile, suggesting a limited influence of the winter monsoon. The EASM appears to have played a more significant role in the dust cycle, with increasing dust fluxes corresponding with lower EASM precipitation. Variations in dust flux from NE drylands display shifts reflecting changes in EASM precipitations and dune activity along the EASM margin, where the dust originates from. To account for the influence of the WJ, we propose that the meridional position and intensity of the WJ also affected dust emission in the drylands’ region. A more northward position of the WJ allows the EASM front further north, generating more precipitations over the NE drylands, reducing the extent of arid areas, and resulting in less dust emission from dune activity, while the opposite occurs with a strong, more southerly WJ. Anthropogenic activities are likely to have had an increasing impact on the dust cycle over the late Holocene. Nevertheless, the presence of inconsistencies in records, coupled with a simultaneous decline in climatic conditions (mainly precipitations) during the same timeframe, hinders the precise assessment of the influence of human activities on dust emissions in the region.