The influence of two lithium forms on the growth, L-ascorbic acid content and lithium accumulation in lettuce plants

LC-MS/MS phenolic profileand remedial role of Urtica dioica extract against Li2CO3-induced toxicity

In this study, the protective role of Urtica dioica extract (Udex) against Li2CO3 toxicity in Allium cepa L. was investigated using various parameters such as germination rates, root growth, weight gain, mitotic index (MI), malondialdehyde (MDA), micronucleus (MN), antioxidant enzyme activity, chromosomal abnormalities (CAs) and anatomical changes. As the biological activity of Udex is related to its active content, the profile of phenolic compounds was determined by LC-MS/MS analysis. Li2CO3 caused abnormalities in the tested parameters and serious regressions in germination parameters. Application of 100 mg/L Li2CO3 reduced the chlorophyll a and b contents by 73.04% and 65.7%, respectively. Li2CO3 application exhibited a cytotoxic effect by inducing significant decreases in MI and increases in the frequency of MN, and also showed a genotoxic effect by causing CAs. After 100 mg/L Li2CO3 treatment, MDA, proline, superoxide dismutase, and catalase levels increased by 54.9%, 58.5%, 47.8%, and 52.3%, respectively. Li2CO3 and Udex co-administration resulted in a regression in increased biochemical parameters and genotoxicity parameters, and an improvement in germination parameters. Furthermore, Udex demonstrated efficacy in mitigating the detrimental effects of Li2CO3 on the root tip, particularly in the 200 µg/mL Udex-treated group. The thickening of the cortex cell wall and conduction tissue, which is commonly induced by Li₂CO₃, was not observed in the Udex-treated group. The protective effect of Udex can be explained by the phenolic compounds it contains. Rutin was detected as the major component in Udex and other phenolics were listed according to their presence rate as protecatechuic acid > caffeic acid > p-coumaric acid > syringic acid > rosemarinic acid > epicatechin. Li ions, which increase in the environment after industrialization, are an important environmental pollutant and exhibit toxicity that affects many pathways in organisms. Scientific research should not only detect these toxic effects but also develop solutions to such problems. In this study, it was determined that the Udex application had a toxicity-reducing role against Li2CO3 toxicity. Also, it has been demonstrated that A. cepa is an important indicator in determining this toxicity and toxicity-reducing applications.

Understanding the effects of lithium exposure on castor bean (Ricinus communis) plants, a potential bioindicator of lithium-contaminated areas

As lithium (Li) stands out as a crucial component of batteries, the inappropriate disposal of electronic gadgets might drive Li pollution in environmentally sensitive environments, such as dumps, where castor bean (Ricinus communis) plant communities are usually found. The exposure to high Li concentration is potentially harmful to the environment and humans. Therefore, it is opportune to evaluate the potential of bioindicator species to monitor Li contamination. In this scenario, the present study assessed the effects of Li exposure on the development of castor bean plants exposed to lithium chloride at five Li dosages (0, 5, 10, 20, and 30 mg dm-3). Significant symptoms of phytotoxicity were observed at all doses. Li dosage exhibited increasing impairment effects on plant biometrics, such as stem diameter and the number of leaves, as well as on the SPAD index, nutritional balance, and biomass production. Our findings suggest castor bean as a potential model species for biomonitoring Li-contaminated areas.

From power to plants: unveiling the environmental footprint of lithium batteries

Widespread adoption of lithium-ion batteries in electronic products, electric cars, and renewable energy systems has raised severe worries about the environmental consequences of spent lithium batteries. Because of its mobility and possible toxicity to aquatic and terrestrial ecosystems, lithium, as a vital component of battery technology, has inherent environmental problems. Leaching of lithium from discharged batteries, as well as its subsequent migration through soil and water, represents serious environmental hazards, since it accumulates in the food chain, impacting ecosystems and human health. This study thoroughly analyses the effects of lithium on plants, including its absorption, transportation, and toxicity. An attempt has been made to examine how lithium moves throughout plants through symplastic and apoplastic pathways and the factors that affect lithium accumulation in plant tissues, such as soil pH and calcium. This review focuses on the possible toxicity of lithium and its impact on ecosystems and human health. Aside from examining the environmental impacts, this review also emphasizes the significance of proper disposal and recycling measures in order to offset the negative effects of used lithium batteries. The paper also highlights the need for ongoing research to develop innovative and sustainable techniques for lithium recovery and remediation.

Upcycling Low-Quality Cotton Fibers into Mulch Gel Films in a Fast Closed Carbon Cycle

Low-quality cotton fibers, often overlooked as low-value materials, constitute a marginalized waste stream in the cotton industry. This study endeavored to repurpose these fibers into mulch gel films, specifically exploring their efficacy in covering moisture-controlled soil beds. Through a meticulously designed series of processing methods, cellulose/glycerol film was successfully fabricated by regenerating cellulose hydrogels in N,N-dimethylacetamide/lithium chloride solutions, followed by plasticization in glycerol/water solutions and hot pressing. The film was then employed to cover soil beds for a duration of up to 252 days, followed by soil burial assessments. Despite expectations of degradation, the film maintained structural integrity throughout the soil covering period but underwent complete biodegradation after 80 days of soil burial, thereby completing a closed carbon cycle. Intriguingly, both tensile strength and modulus exhibited no diminishment but instead increased after soil covering, contrary to expectations given the usual role of degradation. Mechanistic insights revealed that the removal of glycerol contributed to the mechanical enhancement, while microbial activity predominately decomposed the amorphous regions in soil covering and targeted the crystalline portions in soil burial, elucidating the main biodegradation mechanisms. In summary, this study presents, for the first time, the potential of upcycling low-quality cotton fibers into high-value mulch gel films for agricultural practices within a closed carbon cycle.

Lithium-induced alterations in soybean nodulation and nitrogen fixation through multifunctional mechanisms

The increasing footprints of lithium (Li) in agroecosystems combined with limited recycling options have raised uncertain consequences for important crops. Nitrogen (N2)-fixation by legumes is an important biological response process, but the cause and effect of Li exposure on plant root-nodule symbiosis and biological N2-fixation (BNF) potential are still unclear. Soybean as a model plant was exposed to Li at low (25 mg kg-1), medium (50 mg kg-1), and high (100 mg kg-1) concentrations. We found that soybean growth and nodulation capacity had a concentration-dependent response to Li. Li at 100 mg kg-1 reduced the nodule numbers, weight, and BNF potential of soybean in comparison to the low and medium levels. Significant shift in soybean growth and BNF after exposure to Li were associated with alteration in the nodule metabolic pathways involved in nitrogen uptake and metabolism (urea, glutamine and glutamate). Importantly, poor soybean nodulation after high Li exposure was due in part to a decreased abundance of bacterium Ensifer in the nodule bacterial community. Also, the dominant N2-fixing bacterium Ensifer was significantly correlated with carbon and nitrogen metabolic pathways. The findings of our study offer mechanistic insights into the environmental and biological impacts of Li on soybean root-nodule symbiosis and N2-acquisition and provide a pathway to develop strategies to mitigate the challenges posed by Li in agroecosystems.

Assessment of lithium bioaccumulation by quinoa (Chenopodium quinoa willd.) and its implication for human health

Lithium (Li) is the lightest alkali metal and 27th most abundant element in the earth crust. In traces, the element has medicinal value for various disorders in humans, however, its higher concentrations may lead to treatment-resistant depression and altered thyroid functioning. Quinoa (Chenopodium quinoa) has gained popularity owing to its halophytic nature and its potential use as an alternative to the traditional staple foods. However, quinoa response to Li-salt in terms of growth, Li accumulation potential and health risks associated with consumption of the quinoa seeds grown on Li-contaminated soils has not been explored yet. During this study, quinoa was exposed to various concentrations of Li (0, 2, 4, 8 and 16 mM) at germination as well as seedling stages. The results showed that seed germination was the highest (64% higher than control) at Li concentration of 8 mM. Similarly, at 8 mM doses of Li shoot length, shoot dry weight, root length, root dry weight and grain yield were increased by 130%, 300%, 244%, 858% and 185% than control. It was also revealed that Li increased the accumulation of calcium and sodium in quinoa shoots. Carotenoids contents were increased, but chlorophyll contents remained un-changed under Li application. The activities of antioxidants viz. Peroxide dismutase, catalase and super oxide dismutase were also increased with an increase in the levels of Li in the soil. Estimated daily intake and hazard quotient of Li in quinoa were less than the threshold level. It was concluded that Li concentration of 8 mM is useful for quinoa growth and it can be successfully grown on Li contaminated soils without causing any human health risks.

Impact of Low Lithium Concentrations on the Fatty Acids and Elemental Composition of Salvinia natans

The photosynthetic pigments, protein, macro and microelements concentrations, and fatty acids composition of Salvinia natans, a free-floating aquatic plant, were analyzed after exposure to Hoagland nutrient solution containing 1, 3, and 5 mg/L Li. The Li content of Salvinia natans grew exponentially with the Li concentration in the Hoagland nutrient solution. The exposure to Li did not induce significant changes in Na, Mg, K, Cu, and Zn content but enhanced the Ba, Cr, Mn, Ni and Mo absorption in Salvinia natans. The most abundant fatty acids determined in oils extracted from Salvinia natans were C16:0, C18:3(n6), C18:2(n6), and C18:3(n3). The photosynthetic pigments did not change significantly after exposure to Li. In contrast, chlorophyll and protein content decreased, whilst monounsaturated and polyunsaturated fatty acids content increased after the exposure to 1 mg/L Li. The results indicated that Salvinia natans exposed to low Li concentrations may be a good source of minerals, omega 6 and omega 3.

Reimagining safe lithium applications in the living environment and its impacts on human, animal, and plant system

Lithium's (Li) ubiquitous distribution in the environment is a rising concern due to its rapid proliferation in the modern electronic industry. Li enigmatic entry into the terrestrial food chain raises many questions and uncertainties that may pose a grave threat to living biota. We examined the leverage existing published articles regarding advances in global Li resources, interplay with plants, and possible involvement with living organisms, especially humans and animals. Globally, Li concentration (<10-300 mg kg-1) is detected in agricultural soil, and their pollutant levels vary with space and time. High mobility of Li results in higher accumulation in plants, but the clear mechanisms and specific functions remain unknown. Our assessment reveals the causal relationship between Li level and biota health. For example, lower Li intake (<0.6 mM in serum) leads to mental disorders, while higher intake (>1.5 mM in serum) induces thyroid, stomach, kidney, and reproductive system dysfunctions in humans and animals. However, there is a serious knowledge gap regarding Li regulatory standards in environmental compartments, and mechanistic approaches to unveil its consequences are needed. Furthermore, aggressive efforts are required to define optimum levels of Li for the normal functioning of animals, plants, and humans. This review is designed to revitalize the current status of Li research and identify the key knowledge gaps to fight back against the mountainous challenges of Li during the recent digital revolution. Additionally, we propose pathways to overcome Li problems and develop a strategy for effective, safe, and acceptable applications.

Highly Selective Transport and Enrichment of Lithium Ions through Bionic Ion Pair Receptor Nanochannels

Inspired by ion pair cotransport channels in biological systems, a bionic nanochannel modified with lithium ion pair receptors is constructed for selective transport and enrichment of lithium ions (Li⁺). NH₂-pillar[5]arene (NP5) is chosen as ion pair receptors, and the theoretical simulation and NMR titration experiments illustrate that NP5 has good affinity for the ion pair of LiCl through a strong host-guest interaction at the molecular level. Due to the confinement effect and ion pair cooperation recognition, an NP5-based receptor was introduced into an artificial PET nanochannel. An I-V test indicated that the NP5 channel realized the highly selective recognition for Li⁺. Meanwhile, transmembrane transport and COMSOL simulation experiments proved that the NP5 channel achieved the transport and enrichment of Li⁺ through the cooperative interaction between NP5 and LiCl. Moreover, the receptor solution of transmembrane transport LiCl in the NP5 channel was used to cultivate wheat seedlings, which obviously promoted their growth. This nanochannel based on the ion pair recognition will be much useful for practical applications like metal ion extraction, enrichment, and recycle.

Interplay of higher plants with lithium pollution: Global trends, meta-analysis, and perspectives

Lithium (Li) is gaining attention due to rapid rise in modern industries but their ultimate fingerprints on plants are not well established. Herein, we executed a meta-analysis of the existing recent literature investigating the impact of Li sources and levels on plant species under different growth conditions to understand the existing state of knowledge. Toxic effects of Li exposure in plants varies as a function of medium and interestingly, more negative responses are reported in hydroponic media as compared to soil and foliar application. Additionally, toxic effects of Li vary with Li source materials and LiCl more negatively affected plant development parameters such as plant germination (n = 48) and root biomass (n = 57) and recorded highly uptake in plants (n = 78), while LiNO₃ has more negative effects on shoot biomass. The Li at <50 mg L^-1 concentrations significantly influenced the plant physiological indicators including plant germination and root biomass, while 50-500 mg L^-1 Li concentration influence the biochemical parameters. The dose-response relationship (EC₅₀) ranges regarding the exposure medium of Li sources in plant species were observed 24.6-196.7 ppm respectively. The uptake potential of Li is dose-dependent and their translocation/bioaccumulation remains unknown. Future work should include full life cycle studies of the crops to elucidate the bioaccumulation of Li in edible tissues and to investigate possible trophic transfer of Li.

Kinetics of Ion-Exchange Extraction of Lithium from Aqueous Solutions by Protonated Potassium Polytitanates

In this work, protonated forms of potassium polytitanate were obtained by treating the precursor in HCl solution at pH 2.0, 3.0, 4.0, 5.0, 6.0, or 7.0. The synthesized materials were studied using XRD, FTIR, and XRF. The ion-exchange properties were studied using a LiCl solution with a concentration of C(Li+) = 0.01 mol/L. It was shown that extraction of lithium by potassium polytitanates is dependent on their protonation degree. It has been established that the samples with the highest degree of protonation obtained at pH = 2.0 and 3.0 have the highest efficiency in the ion-exchange extraction of Li+ ions from an aqueous solution. For determination of exchange ion rates and the mechanism of the ion-exchange process, pseudo-first- and pseudo-second-order models as well as the Weber–Morris intraparticle diffusion model, were employed. Experimental data with their participation are in good agreement with the pseudo-second-order kinetic model. The calculated kinetic parameters were qe = 0.47–0.52 mmol/g and k2 = 0.25–0.43, depending on the protonation degree of potassium polytitanate. The obtained experimental and calculated values of the sorption capacity were compared with the cation-exchange capacity of materials studied. According to the kinetics study, the mechanism of lithium adsorption by potassium polytitanates with a higher protonation degree is the ion-exchange chemical reaction. Low-cost protonated potassium polytitanates are promising to extract Li+ ions from aqueous solutions with a low concentration, as confirmed by the analysis of the results.

Lithium Accumulation in Salvinia natans Free-Floating Aquatic Plant

The new context of the intensive use of lithium-based batteries led to increased production of Li and Li-containing wastes. All these activities are potential sources of environmental pollution with Li. However, the negative impact of Li on ecosystems, its specific role in the plants' development, uptake mechanism, and response to the induced stress are not fully understood. In this sense, the Li uptake and changes induced by Li exposure in the major and trace element contents, photosynthetic pigments, antioxidant activity, and elemental composition of Salvinia natans were also investigated. The results showed that Salvinia natans grown in Li-enriched nutrient solutions accumulated much higher Li contents than those grown in spring waters with a low Li content. However, the Li bioaccumulation factor in Salvinia natans grown in Li-enriched nutrient solutions was lower (13.3-29.5) than in spring waters (13.0-42.2). The plants exposed to high Li contents showed a decrease in their K and photosynthetic pigments content, while their total antioxidant activity did not change substantially.

Proactive approach to minimize lithium pollution

With the advancements in lithium-ion battery technology, lithium has been extensively used in many electronic products. Lithium usage is expected to increase in the coming decades. Elevated levels of lithium in the environments, including source water and biota, have been recently reported. Lithium can cause soil dispersion and aggerate swelling and can be readily taken up by plants and filter-feeders, potentially causing toxicity to plants, organisms, and human. As learnt from the reactive approach of the Clean Water Act, many emerging pollutants have not been recognized until they have been widespread and reached dangerous levels in the environments. Aftermath cleanup costs are huge, and many of these damages are irreversible. To avoid lithium being the next global contaminant of emerging concern, environmental agencies shall implement proactive regulation and education soon.

Dose-dependent toxicity profile and genotoxicity mechanism of lithium carbonate

The increasing widespread use of lithium, which is preferred as an energy source in batteries produced for electric vehicles and in many electronic vehicles such as computers and mobile phones, has made it an important environmental pollutant. In this study, the toxicity profile of lithium carbonate (Li₂CO₃) was investigated with the Allium test, which is a bio-indicator test. Dose-related toxic effects were investigated using Li₂CO₃ at doses of 25 mg/L, 50 mg/L, and 100 mg/L. The toxicity profile was determined by examining physiological, cytotoxic, genotoxic, biochemical and anatomical effects. Physiological effects of Li₂CO₃ were determined by root length, injury rate, germination percentage and weight gain while cytotoxic effects were determined by mitotic index (MI) ratio and genotoxic effects were determined by micronucleus (MN) and chromosomal aberrations (CAs). The effect of Li₂CO₃ on antioxidant and oxidant dynamics was determined by examining glutathione (GSH), malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD) levels, and anatomical changes were investigated in the sections of root meristematic tissues. As a result, Li₂CO₃ exhibited a dose-dependent regression in germination-related parameters. This regression is directly related to the MI and 100 mg/L Li₂CO₃ reduced MI by 38% compared to the control group. MN and CAs were observed at high rates in the groups treated with Li₂CO₃. Fragments were found with the highest rate among CAs. Other damages were bridge, unequal distribution of chromatin, sticky chromosome, vagrant chromosome, irregular mitosis, reverse polarization and multipolar anaphase. The genotoxic effects were associated with Li₂CO₃-DNA interactions determined by molecular docking. The toxic effects of Li₂CO₃ are directly related to the deterioration of the antioxidant/oxidant balance in the cells. While MDA, an indicator of lipid peroxidation, increased by 59.1% in the group administered 100 mg/L Li₂CO₃, GSH, which has an important role in cell defense, decreased by 60.8%. Significant changes were also detected in the activities of SOD and CAT, two important enzymes in antioxidant defense, compared to the control. These toxic effects, which developed in the cells belonging to the lithium-treated groups, were also reflected in the tissue anatomy, and anatomical changes such as epidermis cell damage, cortex cell damage, flattened cell nucleus, thickening of the cortex cell wall and unclear vascular tissue were observed in the anatomical sections. The frequency of these changes also increased depending on the Li₂CO₃ dose. As a result, Li₂CO₃, which is one of the lithium compounds, and has become an important contaminant in the environment with increasing technological developments, caused a combined and versatile toxicity in Allium cepa L. meristematic cells, especially by causing deterioration in antioxidant/oxidant dynamics.

The Effect of Lithium Salt with Ascorbic Acid on the Antioxidant Status and Productivity of Gestating Sows

This research is aimed at the influence of different doses of lithium ascorbate on pigs’ diet estimation, at farrowing sows’ antioxidant status increase, and at lipid peroxidation product level decrease. The research was conducted in farrowing sows of the Irish landrace breed during the second farrow. Three groups of animals were formed, with ten livestock units in each. Thirty days after successful insemination, the sows of the E10, E5 and E2 experimental groups started receiving lithium ascorbate powder together with feed stuff in dosages of 10, 5 and 2 mg/kg of body weight, respectively. Their weighing and biochemical examinations were performed before the substance introduction as well as on the 60th and 110th days of pregnancy. The following were detected in sows’ blood plasma: malondialdehyde, reduced glutathione, oxidized glutathione, SH/SS ratio, superoxide dismutase and glutathione peroxidase activity. Lithium ascorbate usage during sows’ breeding cycle caused a significant increase in SH (reduced glutathione) level by 21% (p < 0.05), SS (oxidized glutathione) level decrease by 17% (p < 0.05), and malondialdehyde level decrease by 60% (p < 0.05). These data outline antioxidant defense system activization, reducing the risk of oxidative stress under the influence of feeding with lithium ascorbate. Lithium ascorbate in dosages of 10 mg/kg per body weight given together with feed stuff shows prominent adaptogene and stress protective features in the most effective way. The research conducted regarding lithium ascorbate usage for farrowing sows can reduce the negative consequences of oxidative stress, increase sows’ health preservation level, and contribute to fertility boost.

Lithium: Perspectives of nutritional beneficence, dietary intake, biogeochemistry, and biofortification of vegetables and mushrooms

Although lithium (Li) is not an essential nutrient for humans, low Li intakes are associated with increased suicide and homicide rates, aggressive behaviors, unipolar/bipolar disorders, acute mania, etc. On the other hand, Li is one of the most effective psychopharmacological agents used for the treatment of these psycho-behavioral disorders. The beneficial normothymic effect of Li could be achieved at lower doses, therefore, modern psychiatry has called to consider Li biofortification of foods to improve its dietary intake. The concept of agronomic biofortification of crops with Li is juvenile and there exist a limited number of studies, mainly focused on vegetables or mushrooms. This review, first of its kind, discusses the nutritional beneficence and dietary intake of Li, its biogeochemistry, and opportunities and challenges in the Li biofortification of food crops. Literature showed that dietary intake of Li in many countries of the world is insufficient, compared to the provisional recommended dietary allowance (RDA) of 1.0 mg day^-1 for a 70 kg adult. Lithium contents of soils are widely variable and the metal has high mobility in soils, making it more prone to leaching, and available for plant uptake. Biofortification studies reveal that plants can accumulate significant quantities of Li in their edible tissues without yield loss and quality associated negative effects. At lower application rates, Li tissue concentration could reach to the level that consuming 100-200 g of Li-biofortified fresh vegetables or mushrooms could support its RDA. It seems impossible to enrich the plants with Li to the levels that allow their application in psychiatric treatments, which requires the dosage of 600-1200 mg day^-1. However, there is need to refine the methods of Li biofortification strategies to obtains plant specific concentration of Li in edible parts so that consuming a specific amount could provide the proposed dietary intake requirement.

From mine to mind and mobiles - Lithium contamination and its risk management

With the ever-increasing demand for lithium (Li) for portable energy storage devices, there is a global concern associated with environmental contamination of Li, via the production, use, and disposal of Li-containing products, including mobile phones and mood-stabilizing drugs. While geogenic Li is sparingly soluble, Li added to soil is one of the most mobile cations in soil, which can leach to groundwater and reach surface water through runoff. Lithium is readily taken up by plants and has relatively high plant accumulation coefficient, albeit the underlying mechanisms have not been well described. Therefore, soil contamination with Li could reach the food chain due to its mobility in surface- and ground-waters and uptake into plants. High environmental Li levels adversely affect the health of humans, animals, and plants. Lithium toxicity can be considerably managed through various remediation approaches such as immobilization using clay-like amendments and/or chelate-enhanced phytoremediation. This review integrates fundamental aspects of Li distribution and behaviour in terrestrial and aquatic environments in an effort to efficiently remediate Li-contaminated ecosystems. As research to date has not provided a clear picture of how the increased production and disposal of Li-based products adversely impact human and ecosystem health, there is an urgent need for further studies on this field.

A Genome-Wide Screen in Saccharomyces cerevisiae Reveals a Critical Role for Oxidative Phosphorylation in Cellular Tolerance to Lithium Hexafluorophosphate

Lithium hexafluorophosphate (LiPF₆) is one of the leading electrolytes in lithium-ion batteries, and its usage has increased tremendously in the past few years. Little is known, however, about its potential environmental and biological impacts. In order to improve our understanding of the cytotoxicity of LiPF₆ and the specific cellular response mechanisms to it, we performed a genome-wide screen using a yeast (Saccharomyces cerevisiae) deletion mutant collection and identified 75 gene deletion mutants that showed LiPF₆ sensitivity. Among these, genes associated with mitochondria showed the most enrichment. We also found that LiPF₆ is more toxic to yeast than lithium chloride (LiCl) or sodium hexafluorophosphate (NaPF₆). Physiological analysis showed that a high concentration of LiPF₆ caused mitochondrial damage, reactive oxygen species (ROS) accumulation, and ATP content changes. Compared with the results of previous genome-wide screening for LiCl-sensitive mutants, we found that oxidative phosphorylation-related mutants were specifically hypersensitive to LiPF₆. In these deletion mutants, LiPF₆ treatment resulted in higher ROS production and reduced ATP levels, suggesting that oxidative phosphorylation-related genes were important for counteracting LiPF₆-induced toxicity. Taken together, our results identified genes specifically involved in LiPF₆-modulated toxicity, and demonstrated that oxidative stress and ATP imbalance maybe the driving factors in governing LiPF₆-induced toxicity.

Growth and physiological response of spinach to various lithium concentrations in soil

Lithium (Li) exploitation for industrial and domestic use is resulting in a buildup of the element in various environmental components that results in potential toxicity to living systems. Therefore, a soil culture experiment was conducted to evaluate the effects of increasing concentration of Li (0, 20, 40, 60, and 80 mg kg^-1 soil) on spinach growth, the effects of Li uptake, and its effects on various physiological attributes of the crop. The results showed that lower levels of Li in soil (20 mg Li kg^-1) improve the growth of spinach plants, while a higher concentration of applied Li enhanced the pigment contents. Higher concentrations of Li in soil interfered with potassium and calcium uptake in plants. Moreover, increasing Li concentration resulted in higher activities of antioxidant enzymes activity in spinach shoots. From these results, it is concluded that spinach shoot accumulated higher concentrations of Li without showing any visual toxicity symptoms. Therefore, the study concludes that Li ion was mostly deposited in leaves rather than in roots which may cause potential human health risk on the consumption of Li-contaminated plants. Therefore, the cultivation of leafy vegetables in Li-affected soils should be avoided to reduce the potential human health risks.

Cryptic footprints of rare earth elements on natural resources and living organisms

BACKGROUND

Rare earth elements (REEs) are gaining attention due to rapid rise of modern industries and technological developments in their usage and residual fingerprinting. Cryptic entry of REEs in the natural resources and environment is significant; therefore, life on earth is prone to their nasty effects. Scientific sectors have expressed concerns over the entry of REEs into food chains, which ultimately influences their intake and metabolism in the living organisms.

OBJECTIVES

Extensive scientific collections and intensive look in to the latest explorations agglomerated in this document aim to depict the distribution of REEs in soil, sediments, surface waters and groundwater possibly around the globe. Furthermore, it draws attention towards potential risks of intensive industrialization and modern agriculture to the exposure of REEs, and their effects on living organisms. It also draws links of REEs usage and their footprints in natural resources with the major food chains involving plants, animals and humans.

METHODS

Scientific literature preferably spanning over the last five years was obtained online from the MEDLINE and other sources publishing the latest studies on REEs distribution, properties, usage, cycling and intrusion in the environment and food-chains. Distribution of REEs in agricultural soils, sediments, surface and ground water was drawn on the global map, together with transport pathways of REEs and their cycling in the natural resources.

RESULTS

Fourteen REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Th and Yb) were plighted in this study. Wide range of their concentrations has been detected in agricultural soils (<15.9-249.1 μg g^-1) and in groundwater (<3.1-146.2 μg L^-1) at various sites worldwide. They have strong tendency to accumulate in the human body, and thus associated with kidney stones. The REEs could also perturb the animal physiology, especially affecting the reproductive development in both terrestrial and aquatic animals. In plants, REEs might affect the germination, root and shoot development and flowering at concentration ranging from 0.4 to 150 mg kg^-1.

CONCLUSIONS

This review article precisely narrates the current status, sources, and potential effects of REEs on plants, animals, humans health. There are also a few examples where REEs have been used to benefit human health. However, still there is scarce information about threshold levels of REEs in the soil, aquatic, and terrestrial resources as well as living entities. Therefore, an aggressive effort is required for global action to generate more data on REEs. This implies we prescribe an urgent need for inter-disciplinary studies about REEs in order to identify their toxic effects on both ecosystems and organisms.

Subcellular distribution and chemical forms of lithium in Li-accumulator Apocynum venetum

Apocynum venetum is a promising species to remediate an emerging environmental contaminant lithium (Li). However, no research has been conducted so far relating Li tolerance mechanism. In order to improve the understanding of Li transportation and detoxification, subcellular accumulation and distribution of different chemical forms of Li was studied in Apocynum venetum. Subcellular Li compartmentalization analysis showed that majority of Li was located in vacuole (45.52-72.65%) and cell wall (14.84-29.02%) under Li treatment. Furthermore, water soluble and ethonal extracted Li (inorganic Li) are the main chemical forms of Li taken up by A. venetum. With the increase of Li concentration in the medium, Li content in all subcellular fractions and proportion of F-ethanol form with high mobility increased. The greatest amount of Li was found in soluble fraction in leaves at 25 mg L^-1 Li treatment, followed by soluble fraction in leaves at 2.5 mg L^-1. These results suggest that Li compartmentation in leaf vacuoles is important in Li detoxification and Li accumulation of A. venetum.

Tolerance and accumulation of lithium in Apocynum pictum Schrenk

Primarily, lithium (Li) resource development and wider application of Li-ion batteries result in Li pollution and concomitantly poses increasing and inevitable problems to environmental health and safety. However, information is rare about the scope of the remediation of Li contaminated soil. Apocynum venetum is already proved to be a Li-accumulator with high Li tolerance and accumulation (Jiang et al., 2014). However, it is not clear whether Apocynum pictum, another species of the same genus with the same uses as A. venetum, is also a Li-accumulator. We investigated germination, growth and physiological responses of A. pictum to different levels of LiCl. Germination was not significantly affected by low Li concentration (0-100 mmol L-1). As LiCl increased from 100 to 400 mmol L-1, both germination percentage and index decreased gradually. For germination of A. pictum seeds, the critical value (when germination percentage is 50%) in LiCl solution was 235 mmol L-1, and the limit value (when germination percentage is 0%) was 406 mmol L-1. A. pictum could accumulate >1,800 mg kg-1 Li in leaves, and still survived under 400 mg kg-1 Li supply. The high Li tolerance of A. pictum during germination and growth stage was also reflected by activity of α-amylase and contents of soluble sugar, proline and photosynthetic pigments under different Li treatments. The bioconcentration factors (BCF) (except control) and translocation factors (TF) were higher than 1.0. High tolerance and accumulation of Li indicated that A. pictum is Li-accumulator. Therefore, this species could be useful for revegetation and phytoremediation of Li contaminated soil.

Lithium as an emerging environmental contaminant: Mobility in the soil-plant system

Contamination of soil with lithium (Li) is likely to increase due to its wider dispersal in the environment, associated in particular, with the disposal of the now ubiquitous Li-ion batteries. There is, however, a paucity of information on the behaviour of Li in the soil-plant system. We measured the sorption of added Li to soil, and uptake of Li by food and fodder species. Around New Zealand, soil concentrations were shown to range from 0.08 mg/kg to 92 mg/kg, and to be positively correlated with clay content. Most geogenic Li in soil is insoluble and hence unavailable to plants but, when Li⁺ is added to soil, there is only limited sorption of Li. We found that Li sorption increased with increasing soil pH, and decreased proportionately with increasing Li concentrations. Compared to other cations in soil, Li is mobile and may leach into receiving waters, be taken up by plants, or have other biological impacts. In a soil spiked with just 5 mg/kg, plants took up several hundred mg/kg Li into leaves with no reduction in biomass. Lithium appears to be a phloem immobile element, with the highest concentrations occurring in the older leaves and the lowest concentrations occurring in the seeds or fruits. These results may raise concerns and risks in situations where food and fodder crops are associated with waste disposal.

High lithium tolerance of Apocynum venetum seeds during germination

Identification and use of lithium (Li) accumulator plants is a promising strategy to remediate Li-contaminated soil. Apocynum venetum is reported as a Li accumulator. However, its tolerance to Li salt during germination is still unknown. The primary aim of this study was to investigate the effects of two Li salts on seed germination of A. venetum. At the same concentrations, germination percentages in LiCl solution were higher than that in Li₂CO₃ solution. At 25 °C, seeds germinated to 4-90% at 0-400 mmol L^-1 LiCl and 3-91% at 0-150 mmol L^-1 Li₂CO₃. Low concentration (0-50 mmol L^-1) of LiCl did not significantly affect germination percentage. The simulated critical value (when germination percentage is 50%) in LiCl solution is 196 mmol L^-1, and 36 mmol L^-1 for Li₂CO₃. Activity of α-amylase, contents of MDA, soluble sugar, and proline were dramatically affected by Li salts, especially at medium and late germination stages. When compared with control, α-amylase activity of seeds under 25 mmol L^-1 LiCl and 10 mmol L^-1 Li₂CO₃ did not show significant difference. Germination percentage and index, radicle length, and physiological parameters indicate A. venetum seeds are highly tolerant to Li salts during germination, especially LiCl.

Is lithium biologically an important or toxic element to living organisms? An overview

Industrialized world is exposing living organisms to different chemicals and metals such as lithium (Li). Due to their use in common household items to industrial applications, it is imperative to examine their bioavailability. Lithium belongs to the group IA and also has wider uses such as in batteries, air conditioners to atomic reactors. Lithium occurs naturally in soil and water, mostly at low concentrations, and enters the food chain. It is not one of the essential minerals though various studies indicate that low levels of Li have beneficial effects on living organisms, whereas high levels expose them to toxicity and related detrimental effects. This review suggests that Li could be biologically important to living organism depending upon its concentration/exposure. Little is known about its biological importance and molecular understanding of its accumulation and mode of action, which might have future implications for Li's long-term effects on living organisms.

D27E mutation of VTC1 impairs the interaction with CSN5B and enhances ascorbic acid biosynthesis and seedling growth in Arabidopsis

Our previous investigation revealed that GDP-Man pyrophosphorylase (VTC1), a vital ascorbic acid (AsA) biosynthesis enzyme, could be degraded through interaction with the photomorphogenic factor COP9 signalosome subunit 5B (CSN5B) in the darkness, demonstrating the posttranscriptional regulation of light signal in AsA production. Here, we further report that a point mutation in D27E of VTC1 disables the interaction with CSN5B, resulting in enhancement of AsA biosynthesis and seedling growth in Arabidopsis thaliana. To identify the interaction sites with CSN5B, we first predicted the key amino acids in VTC1 via bioinformatics analysis. And then we biochemically and genetically demonstrated that the 27th Asp was the amino acid that influenced the interaction of VTC1 with CSN5B in plants. Moreover, transgenic lines overexpressing the site-specific mutagenesis from D27 (Asp) into E27 (Glu) in VTC1 showed enhanced AsA accumulation and reduced H₂O₂ content in Arabidopsis seedlings, compared with the lines overexpressing the mutation from D27 into N27 (Asn) in VTC1. In addition, this regulation of VTC1 D27E mutation promoted seedling growth. Together, our data reveal that the 27th amino acid of VTC1 confers a key regulation in the interaction with CSN5B and AsA biosynthesis, as well as in Arabidopsis seedling growth.

Lithium toxicity in plants: Reasons, mechanisms and remediation possibilities - A review

Lithium (Li) is a naturally occurring element; however, it is one of the non-essential metals for life. Lithium is becoming a serious matter of discussion for the people who do research on trace metals and environmental toxicity in plants. Due to limited information available regarding its mobility from soil to plants, the adverse effects of Li toxicity to plants are still unclear. This article briefly discusses issues around Li, its role and its essentiality in plants and research directions that may assist in inter-disciplinary studies to evaluate the importance of Li's toxicity. Further, potential remediation approaches will also be highlighted in this review. Briefly, Li influenced the growth of plants in both stimulation and reduction ways, depending on the concentration of Li in growth medium. On the negative side, Li reduces the plant growth by interrupting numerous physiological processes and altering metabolism in plant. The contamination of soil by Li is becoming a serious problem, which might be a threat for crop production in the near future. Additionally, lack of considerable information about the tolerance mechanisms of plants further intensifies the situation. Therefore, future research should emphasize in finding prominent and approachable solutions to minimize the entry of Li from its sources (especially from Li batteries) into the soil and food chain.

Regional differences in plant levels and investigations on the phytotoxicity of lithium

The growing use of lithium (Li) in industrial and energetic applications and the inability to completely recycle the alkali metal will most likely increase anthropogenic emissions and environmental concentrations in the future. Although non-essential to plants, Li(+) is an important ultra-trace element in the animal and human diet and is also used in the treatment of e.g. mental disorders. Most of the lithium is consumed with the drinking water and vegetables, but concentrations in foodstuffs vary with the geochemistry of the element. In order to identify potential risks and to avoid an overmedication due to consumption of Li rich or Li contaminated foods it is advisable to identify background levels and to derive recommended Daily Allowances (RDAs) for the element. Although Germany does not possess large amounts of primary or secondary resources of lithium, geochemical investigations (mineral and ground waters and soils) in this country confirm a wide variation of environmental concentrations with generally higher levels in the southwest. Despite the large number of soil and water data, only very few data exist on lithium concentrations in plants and its phytotoxicity. Within the scope of present study common grassland plant species were sampled in regions of SW-Germany with reportedly high geogenic levels of Li. The data are discussed with regard to literature surveys and existing reference values. Since lithium has phytotoxic effects a greenhouse experiment was performed with different Li salts (LiCl and Li2CO3) and plant species (maize, bean and buckwheat) to derive dose-response relationships for the endpoint shoot growth. While corn growth was not reduced significantly by soil concentrations of 118 ppm, EC50 values in buckwheat were 47 and 16 ppm for lithium derived from LiCl and Li2CO3, respectively.