Rare Earth Elements In Waters Research Articles

Drivers of rare earth elements (REEs) and radionuclides in changing subarctic (Nunavik, Canada) surface waters near a mining project

The emergence of mining projects for rare earth elements (REEs) in response to rising global demand and geopolitical factors introduces environmental concerns, such as the suspected release of anthropogenic REEs to aquatic systems and the coexistence of radionuclides (U, Th). Northern regions confront heightened challenges from limited research and accelerated climate change. Drivers of REEs in surface waters (including George and Koroc rivers, their tributaries, and thermokarst lakes) were studied (2017–2023) in subarctic Canada within a climate transition zone, near a prospective REE mine. Dissolved REEs (<0.45 μm) correlated positively with Al, Fe, Th, U, Cl– and DOC. A novel relationship with water temperature demonstrated an approximate 10-fold decrease in REE concentrations over the environmental gradient (2–20 ℃), suggesting complex implications for REE speciation under climate pressures. Optical analyses further predicted REEs were mobilized by humic-rich, terrestrial DOC, with correlations presenting a possible co-transport with Al, Fe and Th. Relationships for redox-sensitive Ce anomalies (Ce/Ce* = 0.18–1.2) with multi-valent trace metals (Al, Fe, Ti) and DOC were suggestive of a preferential adsorption of Ce by inorganic colloids in low-DOC systems. Findings emphasized the potential for changes in REE geochemistry with ongoing northern surface warming and vegetation shifts.

The addition of 144Nd atomic mass to routine ICP-MS analysis as a Quick Screening Tool for Approximating Rare Earth Elements (Q-STAR) in natural waters

Rare earth elements (REEs) are a class of critical minerals, all of which can have supply chain vulnerability that impacts economic security. These elements are widely measured in environmental matrices via inductively coupled plasma mass spectrometry (ICP-MS); however, successful quantification can require time-consuming, sample-specific optimization. While a sample-by-sample approach is appropriate for targeted quantification studies, this approach is not suitable for mineral exploration efforts where rapidly screening thousands of samples for the presence of REEs is desired. Here, we demonstrated the use of a Quick Screening Tool for Approximating REEs (Q-STAR) to detect REEs in surface water and groundwater matrices, collected as part of existing environmental studies. A mass-to-charge ratio of 144 (m/z = 144) was added to an ICP-MS method to screen for REEs in filtered water samples submitted for metals analyses to the U.S. Geological Survey (USGS) National Water Quality Laboratory. We detected the presence of REEs above a reference threshold of 1200 counts per second in 18 % of pre-selected 6626 samples. Using this screened dataset, we mapped estimated dissolved REE concentrations across the United States in relation to ecoregions and underlying geology. Data are constrained to where sample collection took place but nevertheless show estimated aqueous dissolved REE concentrations on a geographic scale that has not yet been studied. To validate Q-STAR, REEs were measured in a USGS standard reference sample, a subset of 88 archived filtered water samples, and in fresh filtered surface water samples. Our targeted analyses demonstrated a strong linear relationship between Q-STAR predicted and measured values in all archived samples for Nd (r2 = 0.94), and light REEs (LREEs) such as lanthanum (La) (r2 = 0.93), praseodymium (Pr) (r2 = 0.94) and samarium (Sm) (r2 = 0.94). Using Q-STAR screen values, nine field sites were identified and surface water samples recollected to confirm the continued presence of Nd and LREEs. Q-STAR can be used to screen an unlimited number of water samples for the presence of REEs prior to time-intensive and costly quantitative analyses and to generate large REE datasets for further investigation.

Rare earth element extraction from geothermal brine using hybrid capacitive-deionisation process

Rare Earth Elements (REE) in geothermal brine include pollutants such as dissolved Lanthanum, Cerium, Praseodymium, Neodymium, Promethium, Samarium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Erbium, Thulium, Ytterbium, lithium, and other ions. These REEs in geothermal brine, also popularly known as “Vitamins of the modern industry”, are vital for industries such as new energy vehicles, wind turbines, radar systems, laser crystals, etc., and harmful for agriculture and drinking purposes. Hence, identifying, quantifying, and extracting these REEs are essential and economical for a geothermal plant. The present study systematically investigates identifying and quantifying the REE and other essential ions in geothermal brine sources from Gujarat regions. For the extraction of REE from geothermal brine, geothermal brine treatment systems and their integration with automation control are designed in the present work. The proposed system filters geothermal brine and extracts REE through a hybrid filtration setup using capacitive deionization. Solar photovoltaic Water Filtration uses a hybrid Capacitive De-Ionization (CDI) treatment-based prototype to purify water and extract REE. The CDI method is an emerging technology in the desalination systems. It has far greater leverage over other desalination methods such as electrodialysis. The proposed design allows the simultaneous removal of various dissolved organic and inorganic contaminants in geothermal brine.

Occurrence of rare earth elements in water, sediment, and freshwater fish of diverse trophic levels and feeding ecology: Insights from the Po river (northwest Italy)

To date, the occurrence of rare earth elements (REEs) in freshwater ecosystems has garnered limited attention in the scientific literature. Furthermore, a dearth of data exists regarding their potential bioaccumulation in freshwater fish. To fill this knowledge gap, we studied REEs concentrations in water, sediment, and fish specimens collected along the Po River (northwest Italy) and calculated biota-sediment accumulation (BSAF) and bioconcentration (BCF) factors, while taking into account fish feeding behavior and trophic level effects on the overall content of total REEs (ƩREEs). The fish communities were composed of native and non-native species. Remarkably low concentrations of REEs (<0.0003 mg/L) were detected in the water samples, indicating REEs insolubility. In contrast, sediment samples were found to be a good sink for REEs, with a higher mean ƩREEs recorded for the samples from the Moncalieri station (70.93 mg/kg). Notably, no significant differences in ƩREEs concentration were observed in the muscle tissue of fish samples from the three stations. The highest mean ƩREEs was recorded in the samples from the Murazzi station (0.027 mg/kg). The BSAF was very low, consistently below the unit, indicating an absence of bioaccumulation in fish muscle from sediment. In contrast, the BCF was high for several REEs, mainly for Sc and Y. While feeding ecology did not appear to affect REEs accumulation in muscle, there was a significant negative relationship between the trophic level and ΣREEs, indicating a trophic dilution of REEs from predator (Silurus glanis) to planktivorous (Alburnus arborella) fish. This study provides baseline concentrations, trophic transfers, and patterns of REEs in a river system. Further studies are needed to understand the transfer of REEs to other biotic components of lotic ecosystems.

Geochemical behaviors of rare earth elements in granite-hosted geothermal systems in SE China

Rare earth elements (REEs) are effective indicators in tracking water-rock interactions in the hydrothermal systems. Subject to multiple environmental effects, none a unified conclusion has been achieved to generalize the mechanism of diversifying the REEs in various thermal systems. Low-medium temperature hydrothermal systems occurring in fractured-granite exist widely in South China. However, geochemical behavior of REEs in geothermal water is not well studied though there are lots of REEs deposits. This study focuses on hydrogeochemical characteristics of REEs and constrains from salinity. Results show that the TDS (total dissolved solids) mutation due to transfer of sedimentary environments from coastal to relatively inland areas caused the great differentiation of REEs and their species. When TDS is greater than 1 g/L, Ln3+, LnOH2+, LnSO4+, and LnF2+ (Ln represents REEs) prevail and fractions of them except LnOH2+ are positively correlated with TDS. In contrast, when TDS is less than 1 g/L, LnCO3+ and Ln (CO3)2− constitute the most important part and mutually compete in fluids. A positive Eu anomaly is proved to originate primarily from the preferential dissolution of Eu-rich minerals and the seawater intrusion somewhat contributed to the negative Ce anomaly. This work first proposed the salinity effect on REEs by analysis of the in-situ sampling thermal waters that may have been neglected before and provided a new perspective to comprehensively understand the occurrence and migration mechanisms of REEs in different hydrothermal systems.

Determination of heavy metals and rare earth elements in sediment and river water of the Citarum Watershed

Citarum River and its tributary rivers flows through Bandung Regency, with the watershed area about 6080 km2. These rivers play important role for local people in various field. Unfortunately, the anthropogenic activities in Citarum watershed have caused some environmental problems such as erosion, sedimentation, and water quality deterioration. Many various elements and heavy metals enter into the river from industrial waste, domestic waste, and some lithogenic materials where they will be distributed to aquatic ecosystem components such as sediment and aquatic biota. The aim of this research is to determine the distribution of heavy metals and rare earth elements in water and sediment river in Citarum River and its tributary river. The heavy metals and rare earth elements were measured using neutron activation analysis technique that can determine many elements simultaneously. The samples were collected from 10 sampling stations, from Situ Cisanti (upper segment) to Saguling Reservoir inlet, in March 2022. The result indicated that there were 13 elements detected in river water that consist of Na, K, Ca, Al, Mg, Ti, Co, Zn, Rb, Rb, Sb, Cs, La, V. In river sediment, 25 elements were detected that consist of 9 major elements (Na, K, Ca, Fe, Al, Mg, Ti, V, Mn), 10 minor elements (Co, Zn, Rb, Sb, Cs, Ba, Ta, Cs, Th, U, Hf) and 6 rare earth elements (La, Sc, Ce, Sm, Eu, Yb).

Rare earth elements (REEs) behavior in a large river across a geological and anthropogenic gradient

To meet the strong demand for green and digital technologies, the production of rare earth elements (REEs) has increased significantly, yet the fate of REEs (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) in large rivers with multiple hydrological, geochemical, and anthropogenic gradients in their catchments remains poorly documented. Here we evaluated the spatial and temporal evolution of the concentrations, patterns, and speciation of REEs in surface waters along a 550 km transect of the St. Lawrence River (SLR) (Canada) and its tributaries from 2017 to 2020. Particulate and filtered (<0.45 µm) REEs concentrations increased downstream, suggesting that REEs found in the SLR predominantly originate from nearby tributaries, especially those draining the REE-rich Canadian Shield geological formation. Moreover, filtered concentrations were significantly higher in years that experienced intense spring freshets, indicating greater influence of runoff and surface soil processes on water chemistry of the SLR. Correlations with terrestrial-DOM, WHAM speciation modelling, and standardized patterns showed REEs speciation dominated by organic colloids, even in alkaline sites with low DOC and low terrestrial inputs. Strong positive correlations with Fe and Al suggested co-transport on organic matter and adsorption on oxyhydroxides. Compared to the influence of water chemistry and geology, the overall influence of anthropogenic inputs was generally low, although we observed an influence of increased erosion on particulate REEs and we measured anthropogenic gadolinium (Gd) at the Montréal wastewater outlet. Our results provide an integrative understanding of the fate of REEs through a geochemical and landscape perspective in one of the largest rivers in North America.

Riparian Bird Occupancy in a Mountain Watershed in the Colorado Mineral Belt Appears Resilient to Climate-Change-Driven Increases in Metals and Rare Earth Elements in Water and Aquatic Macroinvertebrates

Acid rock drainage (ARD) impacts species composition in mountain streams. The potential impact for riparian birds experiencing elevated metal uptake by consumption of benthic invertebrates is concerning but not well studied. We investigated the influence of metal and rare earth element (REE) content in benthic invertebrates on the presence of breeding birds in an ARD-impacted watershed in Colorado, USA, where tree swallows in nest boxes had previously been found to have elevated metal concentrations at some sites. The concentrations of particular REEs in invertebrates were higher than those for cadmium or lead. Avian point counts indicated that most bird species detected were present at most sites, and that tree swallows were rarely found. Occupancy models showed that the availability of shrub or forest habitat was a good predictor for a few habitat-specialists, but metal and REE concentrations in water and invertebrates were not good predictors of avian presence. For other species, neither habitat type nor water quality were important predictors. Overall, this study indicates that the climate-change-driven increases in metals and REEs may not influence the presence of riparian birds in ARD-impacted streams.

Evaluation of the rare earth elements phytotoxicity on the example of La and Ce

Interest in the study of the toxicity of rare earth elements (REE) naturally increases with an increase in their consumption. The growth of exploration, development and mining of rare earth metals poses a serious threat to the environment, increasing the concentration of REE in air, water and soil. In this work, we assessed the phytotoxicity of cerium and lanthanum, as the most common rare earth lanthanides in the earth’s crust, using test systems with oats (Avena Sativa L.) and onion (Allium cepa L.). For both test objects, the toxic effect of high concentrations of lanthanum and cerium has been proven. In addition to the inhibition of the development of onion roots, a visually determined thickening and yellowing of the root cap, a change in the cells of the root merisystem were noted. For oats at high concentrations of lanthanum and cerium, yellowing of the roots and inhibition of their development, slowing down the growth of seedlings were also noted. At the same time, for oats at low concentrations of the studied substances, the effect of hormesis was noted.

Distribution, source and behavior of rare earth elements in surface water and sediments in a subtropical freshwater lake influenced by human activities

As tracers, rare earth elements (REEs) can reflect the influence of human activities on the environmental changes in aquatic systems. To reveal the geochemical behavior of REEs in a water–sediment system influenced by human activities, the contents of REEs in the surface water and sediment in the Chaohu Lake Basin were measured by inductively coupled plasma mass spectrometry (ICP–MS). The results show that the ΣREE contents in the surface water are 0.10–0.850 μg L−1, the ΣREE contents in the sediments are 71.14–210.01 μg g−1, and the average contents are 0.24 μg L−1 and 126.72 μg g−1, respectively. Almost all water and sediment samples have obvious light REE (LREE) enrichment, which is the result of the input of LREE-rich substances released by natural processes and human activities (industrial and agricultural production). Under the alkaline water quality conditions of Chaohu Lake, REEs (especially LREEs) are easily removed from water by adsorption/coprecipitation reactions with suspended colloidal particles, which leads to the enrichment of LREEs in sediments. The Ce anomaly of the water–sediment system is related to the oxidation environment, while the Eu anomaly is related to the plagioclase crystallization. Significant Gd anomalies was observed in the downstream of rivers flowing through urban areas, which was related to the anthropogenic Gd wastewater discharged by hospitals. The ∑REE–δEu and provenance index (PI) discrimination results are consistent, indicating that the sediments in Chaohu Lake mainly come from rivers flowing through the southwest farmland. Furthermore, the spatial distribution of REEs shows that these tributaries are significantly affected by agricultural activities. The distribution and accumulation of REEs in Chaohu Lake are the result of the interaction of natural and human processes. The results can provide a scientific reference for the distribution and environmental behavior of REEs in aquatic environments disturbed by human beings.

Water quality criteria for lanthanum for freshwater aquatic organisms derived via species sensitivity distributions and interspecies correlation estimation models

The increasing exploitation and application of rare earth elements (REEs) may induce hazardous risks to freshwater aquatic organisms. Due to the lack of water quality criteria (WQC) and sufficient reliable toxicity data, little information is available on the ecological risk of REEs in surface water. In this study, lanthanum (La) toxicity data were collected from published toxicological studies, and the data quality was assessed using a toxicological data reliability assessment tool. To obtain more toxicity data, Daphnia magna, Cyprinus carpio, and Dania rerio embryos were selected as surrogate species, and an interspecies correlation estimation (ICE) model was used to predict the toxicity of La for untested species. The species sensitivity distributions (SSDs) of La toxicity and WQC were investigated. Differences were observed in the hazardous concentrations for 5% of species (HC5), but no statistically significant differences were noted in the SSD curves between the measured acute toxicity data and the predicted data. For the SSDs constructed from the measured toxicity data, the ICE-predicted toxicity data and all acute data supplemented with the ICE-predicted data, the acute WQC values of La were 88, 1022 and 256 μg/L, respectively. According to the SSD and corresponding HC5 of chronic toxicity data, the chronic WQC was 14 μg/L. The results provide a scientific reference for establishing WQC for freshwater aquatic organisms and ecological risk assessments of REEs.

Effects of in situ leaching on the origin and migration of rare earth elements in aqueous systems of South China: Insights based on REE patterns, and Ce and Eu anomalies

In situ leaching of ion-adsorption rare earth element (REE) deposits has released large amounts of REE-containing wastewater. However, the origin, speciation, distribution and migration of REEs in aqueous systems of the mining catchment are poorly understood. Groundwater, surface water, in situ leachates and weathered granite soil samples were collected from a catchment affected by mining activities in South China. The REE concentrations in groundwater (6.18 × 10–3–0.49 μmol L–1) and surface water (2.54–44.05 μmol L–1) decreased from upstream to downstream. REEs in groundwater were detected in organic matter associated (FA-REE) colloids, while the REE3+ and REE(SO4)+ were converted to REE(CO3)+ and FA-REE colloids from leachates and upstream surface water to downstream. The REE patterns of leachates and upstream groundwater (light and middle REE enrichment) resembled those of soil, but showed heavy REE enrichment due to FA-REE colloids in the downstream. REE in surface water were derived from middle REE enriched leachate. The Ce and Eu anomalies in the water samples indicated the REE origin (i.e., mining activities) and the hydrological variations (e.g., oxidation environment and water-rock interaction). Our results reveal the origin and fate of REE in aqueous systems of ion-adsorption REE mining catchments.

Anthropogenic Gd in urban river water

As an emerging contaminant, rare earth elements (REEs) are becoming an environmental concern, especially in Chinese cities. This study investigated the distribution of REEs in river water and tap water samples in Guiyang, Southwest China. In all water samples, the concentrations of total dissolved REE (∑REE) ranged from 15.1 to 53.3 ng·L–1, with the heavy rare earth elements enriched than the light rare earth elements. Most of the water samples showed significant positive Gd anomalies, with the highest abnormal value calculated to be 29.23. The main reason for the positive Gd anomalies was found to be the release of medical wastewaters containing Gadopentetic acids (Gd-DTPA). Overall, anthropogenic Gd could contributed &amp;gt;60% of total Gd in river waters and tap waters. Because Gd-DTPA is commonly used in large Chinese hospitals, the results of this study implied that anthropogenic Gd release could be common in Chinese cities.

Fast removal of samarium ions in water on highly efficient nanocomposite based graphene oxide modified with polyhydroquinone: Isotherms, kinetics, thermodynamics and desorption

Nowadays, the removal of the rare-earth elements in water and hydrogeosystems is an urgent issue. Therefore, graphene oxide / polyhydroquinone nanocomposite was used to remove samarium ions (Sm3+) in aqueous solutions. The sorption and desorption of Sm3+ ions on the graphene oxide / polyhydroquinone nanocomposite from aqueous solutions are studied with contact time (15.0 min.), initial concentration (100.0 mg/L), the weight of sorbent (0.3 g/L), pH of a solution (6.0) and temp. (25C°). The rate constants of sorption, equilibrium sorption capacity, percentage sorption and desorption, entropy and enthalpy of Sm3+ extraction process are discussed. The analysis of the proceed mechanisms is conducted with the kinetic dependences and sorption isotherms, for which reason the empirical equations of pseudo-first and pseudo-second-order, Elovich and intraparticle diffusion, as well as the equations of Langmuir, Freundlich, Temkin, Dubinin-Radushkevich were used. It should be noted that the absorption of Sm3+ proceeded according to the mixed diffusion mechanism and is controlled by the interactions among the sorbent and the functional groups of the sorbent. According to Langmuir's model, the maximum sorption capacity of the developed sorbent was 357.14 mg g−1. Thus, the high efficiency of the developed sorbent for the purification and remediation of hydrogeosystems for samarium ions is useful. The reported method may be used for the removal of 360 million tons of wastewater with rare earth elements including samarium ions.

Precipitation of secondary minerals in acid sulphate-chloride waters traced by major, minor and rare earth elements in waters: The case of Puracé volcano (Colombia)

Major, minor and rare earth elements were analyzed in the acid sulphate - chloride thermal springs associated to Puracé volcano – hydrothermal system. The waters of Puracé were classified in 2 different groups as a function of the physico-chemical parameters and element distributions. Group 1 is characterized by the highest pH (⁓ 3.5), an outlet temperature of ⁓ 81 °C and a strong depletion of Fe, Al, Si and Ba with respect to the isochemical dissolution of the average volcanic local rock. Group 2 waters have lower pH values ⁓ 1.9 and temperature (⁓ 48 °C) compared with Group 1. Moreover, Group 2 is not characterized by a typical pathway representing the congruent dissolution of the rock and shows a distribution of major and minor elements that is more close to the near-congruent dissolution of the average volcanic local rock with respect to Group 1. These geochemical features of major and minor elements allow to propose that the chemical composition of the waters of Group 1 is strongly affected by the precipitation of secondary minerals such as alunite, jarosite, kaolinite, barite and polymorphs of SiO2.The grouping of waters is also supported by the distribution of dissolved REE normalized to the average volcanic local rock. Group 1 shows REE patterns strongly depleted in light rare earth elements (LREE), typical of water that formed alunitic and/or kaolinitic rocks. On the contrary, Group 2 is characterized by flat patterns, in according to the near-congruent dissolution of the rocks. REE dissolved in waters of Puracé were compared with REE in the acidic waters of Nevado del Ruiz and Azufral Colombian volcanoes and with REE in minerals recognized in advanced argillic alteration (alunite, gypsum and kaolinite). Precipitation of secondary minerals is proposed as a common process depleting LREE in acidic sulphate – chlorine waters in volcano – hydrothermal systems.Furthermore, the chemical fractionation of the major and minor elements was interpreted together with the corresponding distributions of REE in order to trace the water – rock interaction processes. Saturation indexes of most common secondary minerals identified in advanced argillic alterations were calculated using PHREEQC software in a range of temperature from 25 to 250 °C. This geochemical approach allows to identify the possible mineral precipitation or dissolution of secondary minerals as well as the temperature at which the water reached equilibrium with a given set of minerals. In Group 1, the precipitation of secondary minerals LREE enriched (alunite minerals and kaolinite) was traced at temperature of precipitation higher than ⁓ 101 °C.

Geochemical behavior of rare earth elements in acid drainages: Modeling achievements and limitations

Rare earth elements (REE) concentrations in acid mine drainage (AMD) are several orders of magnitude higher than those in other surface waters and could be a future supplementary source of highly valuable REE. Therefore, knowing the mobility constraints of REE in natural waters, particularly in AMD, is of interest.Precipitation of schwertmannite and basaluminite occurs due to mixing of REE-enriched AMD and neutral streams. The REE fractionation between AMD and solid phases has been investigated in several localities in the Odiel-Tinto (SW Spain) and Arroyo del Val (N Spain) basins. The mobility of REE is related to the precipitation of Fe and Al phases that occurs at different pH values. The behavior of REE during the mixing is conservative under low pH conditions (pH <4 approximately), at which schwertmannite precipitates, whereas REE are scavenged under near-neutral pH conditions, at which basaluminite precipitates and what suggest that this phase could be responsible for REE retention. Indeed, when Fe and Al phases can be sampled separately, schwertmannite does not contain REE, which are entirely retained in basaluminite, confirming the REE removal by this later phase.The strengths and limitations of a recently proposed thermodynamic model of REE sorption on basaluminite have been assessed by comparing the model predictions with observations of samples recovered in the field. The model is able to predict the REE distribution pattern and confirms the preferential sorption of heavy REEs (HREEs) and Y over light REEs (LREEs) in all the samples. However, the lack of synchronicity between basaluminite precipitation and REE sorption during mixing in an open flow setting precludes an accurate prediction of the REE concentration in the solid phase.

Labrador Sea bottom water provenance and REE exchange during the past 35,000 years

Deep waters of the Labrador Sea (LS) are important contributors to the Atlantic Meridional Overturning Circulation, but their water mass structure has been highly variable and sensitive to climatic changes on different time scales. The LS is also an area of intense exchange of rare earth elements (REE) between seawater and the underlying sediments, which complicates the reconstruction of past deep water provenance based on radiogenic neodymium (Nd) isotopes. Most notably, Northwest Atlantic Bottom Water exchanges Nd with Archaean age Laurentian detritus, resulting in a significant shift to less radiogenic Nd isotope signatures before it enters the North Atlantic to form the deep part of North Atlantic Deep Water. Here we show that the authigenic fractions of LS core top sediments carry Nd isotope signatures intermediate between bottom water and detritus and thus reflect pore waters that incorporate a mixture of both signatures.We furthermore find that detrital imprints on pore waters led to shifts of REE patterns in the authigenic fraction towards detrital signatures in the past during times of enhanced supply of glacially eroded material from Hudson Bay to the LS, as recorded by radiogenic lead isotopes. This allows an estimation of the intensity of past benthic REE exchange inside the LS.We exploit variations in the mid REE enrichment in the authigenic phase to propose a correction to one LS Nd isotope record for detrital imprints originating from pore water exchange. The corrected ϵNd signatures are argued to more accurately reflect those of past bottom waters. This correction results in past LS bottom water signatures of −16 ± 1 during MIS 2 and 3, considerably less radiogenic than today. This implies that no southern sourced waters advanced into the LS during the last 35 ka and instead supports continuous bottom water sourcing from the Nordic Seas. It thus seems likely that LS bottom waters supplied unradiogenic Nd to abyssal Glacial North Atlantic Bottom Water in the Northwest Atlantic, as was previously hypothesized.

Preparation and application of iron oxide/persimmon tannin/ graphene oxide nanocomposites for efficient adsorption of erbium from aqueous solution

Rare earth elements (REEs) are used for the development of new energy materials owing to their intrinsic physicochemical property. However, excess REEs in water threaten the safety of animals, plants and humans. An efficient way to separate REEs from the water is therefore needed. In this study, a biosorbent consisting of iron oxide (Fe3O4), persimmon tannin (PT), and graphene oxide (GO) as Fe3O4/PT/GO was prepared, and the adsorption of trivalent erbium (Er3+) ions from aqueous solution was investigated. The adsorption process for Er3+ ions conforms to pseudo-second order kinetic and the Langmuir isotherm model behavior. Thermodynamic studies indicate that the adsorption process is spontaneous and endothermic. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET) analysis, and vibrating sample magnetometer (VSM) were used to assess the adsorption mechanism of Er3+ ions onto the Fe3O4/PT/GO biosorbent. A combination of electrostatic interactions, redox reactivity and chelation are responsible for adsorption of Er3+ ions on the Fe3O4/PT/GO biosorbent. The magnetic Fe3O4/PT/GO biosorbent can be easily separated under the magnetic field for effective recycle of Er3+ ions from aqueous solution. Therefore, this new biomass composite holds great promise for wastewater treatment.

Major, trace, and rare earth element geochemistry of the Ayder and İkizdere (Rize, NE Turkey) geothermal waters: Constraints for water–rock interactions

This study aims to determine the sources of rare earth elements (REEs) in the geothermal and cold waters of the Ayder and İkizdere (Rize) geothermal fields (NE Turkey). The differentiation stages of REEs in water–rock interactions as well as the migration processes of aqueous complexes of rare earth elements (REEs) in the waters were evaluated. Based on results for major ions, the İkizdere geothermal water with a temperature of 61 °C can be classified as Na-Ca-HCO3 type water, whereas the Ayder geothermal water with a temperature of 54 °C can be classified as Na-Ca-CO3−SO4 type water. ∑REE concentrations were between 0.64–2.13 μg/L in the İkizdere geothermal field and between 0.01–0.32 μg/L in the Ayder geothermal field. As well as lower pH values, the waters in the İkizdere geothermal field were found to have higher REE concentrations than those of the Ayder geothermal field. Geochemical characteristics of REEs from the host rocks and water samples indicate that the REEs are derived from granite and granodiorite host rocks. Normalized REE plots for the host rocks and waters showed similar patterns, and in particular, the waters interacting with granitic rocks display a pronounced positive Eu anomaly and a less clear Ce anomaly. The positive Eu anomaly in the altered surrounding rocks is associated with argillization of feldspars in the granitic host rocks that the waters have passed through. Application of a speciation model showed that amorphous iron oxy-hydroxide complexes of REEs were significant for a pH value of nearly 9 in the Ayder geothermal waters whereas fluoride complexes are dominant in the İkizdere geothermal waters whose pH is just below 7.

Patterns of the Distribution of Rare-Earth Elements in Waters of Mud Volcanoes

The original data on the distribution of rare-earth elements in waters of mud volcanoes of Sakhalin Island, Taman Peninsula, and Azerbaijan are presented. It has been shown that the mud volcano waters with a sum of rare-earth elements less than 0.5 μg/l are enriched with heavy lanthanides and characterized by a deficiency of Ce. As illustrated by the Yuzhno-Sakhalinsk mud volcano, the content of rare-earth elements is higher in active gryphons.