Search Results (7)

Environmentally friendly and low-emission extraction methods are needed to meet worldwide rare earth element (REE) demand. Within a greenhouse setting, this study aims to investigate the REE hyperaccumulation ability of four plant species (e.g., Phalaris arundinacea, Solanum nigrum, Phytolacca americana, and Brassica juncea) and the impact of amending REE-rich soil with biochar or fertilizer and watering with citric acid solution. Harvested samples were pyrolyzed, and the resulting bio-ores were acid-digested and underwent elemental analysis to determine REE content. Amending soil with fertilizer and biochar increased bio-ore production, while plant species explained the most variation in bioaccumulation factor. The results indicate that Phalaris arundinacea achieved the highest average REE concentration of 27,940 µg/g for the targeted REEs (comprising cerium, lanthanum, neodymium, praseodymium, and yttrium) and 37,844 µg/g for total REEs. It is also found that soil amendment and plant species are critical parameters in the design and implementation of Idaho-based REE phytomining operations. The life cycle assessment study estimated that the electricity demand of the greenhouse contributed the most to GHG emissions during the greenhouse study. Within the field study, electricity demand of the pyrolysis reactor was determined to be the largest producer of GHGs. The techno-economic analysis estimated that the total cost of growing P. arundinacea for six weeks on a one-acre field area is USD 6213, including 39%, 22%, 21%, and 18% of that cost derived from cultivation, biomass processing, soil treatment with fertilizer, and pyrolysis, respectively. It is concluded that the proposed low-emission extraction pathway, which combines phytomining, drying, and pyrolysis, is a promising sustainable approach for REE extraction, especially from REE-rich soil sourced in Idaho. Full article

In this study, we aimed to investigate the occurrence of rare earth elements (REEs) in commonly consumed foods and assess the dietary exposure risks among different age groups in Zhejiang Province. The results showed that tea and shrimp had the highest REE detection rates, reaching 100%. Of all the food categories examined, tea exhibited the highest REE concentrations, significantly exceeding those in other foods. This may be attributed to differences in moisture content, root absorption mechanisms, and processing methods. The concentration pattern of REEs in all samples occurred in the following order: cerium > lanthanum > yttrium > neodymium > neodymium > scandium > praseodymium > gadolinium > dysprosium. The light REEs/heavy REEs (HREEs) ratio was consistently > 2 but remained lower than the ratios observed in the soil and sediments, indicating a potential risk of HREE enrichment. Dietary exposure assessments revealed that the total REE intake among Zhejiang residents was below the established safety threshold (51.3 µg/kg BW/day), with children experiencing the highest exposure (3.71 µg/kg BW/day), primarily due to their lower body weight. In the assessment of individual rare earth elements, Ce exposure in children aged ≤ 6 years exceeded the toxicological reference value. However, this threshold was established based on studies in pregnant and lactating populations and might not be directly applicable to young children. Therefore, overall dietary exposure to individual REEs remains within safe limits. REE exposure from tea consumption did not pose a health risk, even for habitual tea drinkers. These findings underscore the importance of continuous monitoring of REE accumulation in food and additional research on the potential long-term health effects, even though the current exposure levels of REEs are below the established safety limit. This is especially important considering the bioaccumulative nature of REEs and the limited paucity of toxicological data, particularly in vulnerable populations. Full article

In this study, the total content of REEs ranged from 1.32 to 67.74 μg/kg, with a predominant presence of light REEs. The ΔEu and ΔCe values, which exceeded and approached 1, respectively, indicated positive Eu anomalies and low Ce anomalies. Wild fish were categorized into high-, medium-, and low-REEs-bioaccumulation groups using cluster analysis. Higher LRs/HRs and ΔEu values, coupled with lower ΔCe values, in fish from the high-bioaccumulation group suggested that increased bioaccumulation mitigated fractionation. Omnivorous fish with higher REEs levels and lower LRs/HRs indicated broader feeding sources may enhance REE bioaccumulation and diminish fractionation. Elevated REEs concentrations and LRs/HRs in demersal fish highlighted a preferential accumulation of light REEs in the benthic environment. Smaller fish with higher REEs levels but lower LRs/HRs were likely associated with complex feeding sources. Regression analysis revealed that fish with lengths and weights of less than 18 cm and 130 g, respectively, were more susceptible to REEs bioaccumulation. Despite higher ADI values indicating a greater risk for children and Pelteobagrus fulvidraco, all ADI values within 70 μg/(kg·d) suggested that fish consumption poses no risk. This study confirmed that the fractionation of REEs in fish can be used to trace their bioconversion. Full article

Mining activities create disturbed and polluted areas in which revegetation is complicated, especially in northern areas. For the first time, the state of the ecosystems in the impact zone of tailings formed during the processing of rare earth element deposits in the Subarctic have been studied. This work aimed to reveal aspects of accumulation and translocation of trace and biogenic elements in plants (Avenella flexuosa (L.) Drejer, Salix sp., and Betula pubescens Ehrh.) that are predominantly found in primary ecosystems on the tailings of loparite ores processing. The chemical composition of soil, initial and washed plant samples was analyzed using inductively coupled plasma mass spectrometry. Factor analysis revealed that anthropogenic and biogenic factors affected the plants’ chemical composition. A deficiency of nutrients (Ca, Mg, Mn) in plants growing on tailings was found. The absorption of REE (Ce, La, Sm, Nd) by A. flexuosa roots correlated with the soil content of these elements and was maximal in the hydromorphic, which had a high content of organic matter. The content of these elements in leaves in the same site was minimal; the coefficient of REE bioaccumulation was two orders of magnitude less than in the other two sites. The high efficiency of dust capturing and the low translocation coefficient of trace elements allow us to advise A. flexuosa for remediation of REE-contained tailings and soils. Full article

The increasing use of nanoparticles is causing a threat to the environment and humans. The aim of this work was to evaluate the effects of the quenching procedure of biochar production on the biochar capacity to retain the CeO₂ nanoparticle (CeO₂NP) in soil. The effects on Lepidium sativum L. (watercress) were considered. Two biochars were produced from fir wood pellets under the same pyrolysis conditions but with different quenching procedures: dry quenching and wet quenching. The two biochars (BCdryQ and BCwetQ) were separately added to a CeO₂NP-spiked soil (1000 mg kg⁻¹) at the dose 5%_DW and placed in 12 lysimeters under controlled conditions. Lepidium sativum L. seeds were sowed on each lysimeter. The lysimeters were irrigated once a week for 7 weeks, and the leachates were collected. At the end of the experiment, the aboveground biomass was harvested; the total number of plants and the number of plants at the flowering stage were counted, and the height of the tallest plant and the total dry biomass were measured. The data showed that the quenching procedure influences the CeO₂NP retention in soil, and BCdryQ can reduce the leaching of the nanoparticles. Biochar significantly increased the flowering in plants, and BCwetQ reduced the biomass production. This work highlights the importance of the biochar production process for soil applications. The production settings are crucial in determining the efficacy of the product for its ultimate use. Full article

Rare earth elements (REEs) or “technology metals” were coined by the U.S. Department of Energy, a group of seventeen elements found in the Earth’s crust. These chemical elements are vital and irreplaceable to the world of technology owing to their unique physical, chemical, and light-emitting properties, all of which are beneficial in modern healthcare, telecommunication, and defense. Rare earth elements are relatively abundant in Earth’s crust, with critical qualities to the device performance. The reuse and recycling of rare earth elements through different technologies can minimize impacts on the environment; however, there is insufficient data about their biological, bioaccumulation, and health effects. The increasing usage of rare earth elements has raised concern about environmental toxicity, which may further cause harmful effects on human health. The study aims to review the toxicity analysis of these rare earth elements concerning aquatic biota, considering it to be the sensitive indicator of the environment. Based on the limited reports of REE effects, the review highlights the need for more detailed studies on the hormetic effects of REEs. Aquatic biota is a cheap, robust, and efficient platform to study REEs’ toxicity, mobility of REEs, and biomagnification in water bodies. REEs’ diverse effects on aquatic life forms have been observed due to the lack of safety limits and extensive use in the various sectors. In accordance with the available data, we have put in efforts to compile all the relevant research results in this paper related to the topic “toxicity effect of REEs on aquatic life”. Full article

This work investigated a rare earth element (REE) natural biogeochemical cycle in an area with a light rare earth element (LREE)-rich ferrocarbonatite intrusion. An REE determination in this geological environment allowed us to trace REE natural transfers in order to better manage future REE mining exploitations. Our findings suggest that although REE concentrations in abiotic compartments (soil and freshwater systems) and biotic samples (terrestrial and aquatic plants) were low, the LREE fractionation observed in the parent material was maintained along compartments. Additionally, Nd anomalies observed in the sediment pore water suggest a potential different biogeochemical cycle of this element in aquatic systems. According to the potential bioaccumulation of REEs in the organisms of two studied plants belonging to terrestrial and aquatic compartments, Equisetum arvense L. and Typha latifolia L. (respectively), we observed that REEs were not accumulated and that they showed limited REE transfer inside plants, but with an increased uptake of Eu relative to the other REEs. Our results indicated a low mobility and transfer of REEs from REE-rich bedrocks in a natural area toward terrestrial and freshwater systems, but also pointed to a dilution of the REE content in the different compartments, maintaining the LREE fractionation. Our findings provide new knowledge about the REE biochemical cycle in a natural area (from rocks to plants) and represent a starting point for an environmentally friendly exploitation of future REE mining areas. Full article