Phytoextraction of rare earth elements in herbaceous plant species growing close to roads

Rare Earth and Platinum Group Elements In Sub-Saharan Africa and Global Health: The Dark Side of the Burgeoning of Technology

Despite steady progress in the development and promotion of the circular economy as a model, an overwhelming proportion of technological devices discarded by the Global North still finds its way to the Global South, where technology-related environmental health problems start from the predation of resources and continue all the way to recycling and disposal. We reviewed literature on TCEs in sub-Saharan Africa (SSA), focussing on: the sources and levels of environmental pollution; the extent of human exposure to these substances; their role in the aetiology of human diseases; their effects on the environment. Our review shows that even minor and often neglected technology-critical elements (TCEs), like rare earth elements (REEs) and platinum group elements (PGEs), reveal the environmental damage and detrimental health effects caused by the massive mining of raw materials, exacerbated by improper disposal of e-waste (from dumping to improper recycling and open burning). We draw attention of local research on knowledge gaps such as workable safer methods for TCE recovery from end-of-life products, secondary materials and e-waste, environmental bioremediation and human detoxification. The technical and political shortcomings in the management of TCEs in SSA is all the more alarming against the background of unfavourable determinants of health and a resulting higher susceptibility to diseases, especially among children who work in mines and e-waste recycling sites or who reside in dumping sites.This paper demonstrates, for the first time, that the role of unjust North-South dynamics is evident even in the environmental levels of minor trace elements and that the premise underlying attempts to solve the problem of e-waste dumped in Africa through recycling and disposal technology is in fact misleading. The influx of foreign electrical and electronic equipments should be controlled and limited by clearly defining what is a 'useful' second-hand device and what is e-waste; risks arising from device components or processing by-products should be managed differently, and scientific uncertainty and One Health thinking should be incorporated in risk assessment.

Concentration and health risk assessment of 16 rare earth elements in six types of tea in China

Rare Earth Elements (REEs) have been implicated in potential health effects. However, the health risk of REE exposure among tea drinkers in China remains poorly understood. This study aimed to characterize the concentration of REEs in different tea categories and evaluate the associated health risks for tea consumers in China. By analyzing the content of 16 REEs in 4326 tea samples from China, the exposure level of REEs to the general population was estimated. The content of these 16 REEs was similar across six types of tea, with oolong tea exhibiting the highest levels. The concentration of light rare earth elements (LREEs) in six types of tea was higher than that of heavy rare earth elements (HREEs). The daily mean and 95th percentile (P95) exposure to REEs from tea for the general population in China were 0.0328 μg/kg BW and 0.1283 μg/kg BW, respectively, which are significantly lower than the temporary acceptable daily dose (tADI). Our findings suggest that REEs from tea do not pose a known health risk to Chinese consumers.

Advancing phytomining: Harnessing plant potential for sustainable rare earth element extraction

Rare earth elements (REEs) are pivotal for advanced technologies, driving a surge in global demand. Import dependency on clean energy minerals raises concerns about supply chain vulnerabilities and geopolitical risks. Conventional REEs productionis resource-intensive and environmentally harmful, necessitating a sustainable supply approach. Phytomining (agromining) utilizes plants for eco-friendly REE extraction, contributing to the circular economy and exploiting untapped metal resources in enriched soils. Critical parameters like soil pH, Casparian strip, and REE valence influence soil and plant uptake bioavailability. Hyperaccumulator species efficiently accumulate REEs, serving as energy resources. Despite a lack of a comprehensive database, phytomining exhibits lower environmental impacts due to minimal chemical usage and CO2 absorption. This review proposes phytomining as a system for REEs extraction, remediating contaminated areas, and rehabilitating abandoned mines. The phytomining of REEs offers a promising avenue for sustainable REEs extraction but requires technological advancements to realize its full potential.

Insight study of rare earth elements in PM2.5 during five years in a Chinese inland city: Composition variations, sources, and exposure assessment

The booming development of rare earth industry and the extensive utilization of its products accompanied by urban development have led to the accelerated accumulation of rare earth elements (REEs) as emerging pollutants in atmospheric environment. In this study, the variation of REEs in PM2.5 with urban (a non-mining city) transformation was investigated through five consecutive years of sample collection. The compositional variability and provenance contribution of REEs in PM2.5 were characterized, and the REEs exposure risks of children and adults via inhalation, ingestion and dermal absorption were also evaluated. The results showed an increase in the total REEs concentration from 46.46 ± 35.16 mg/kg (2017) to 81.22 ± 38.98 mg/kg (2021) over the five-year period, with Ce and La making the largest contribution. The actual increment of industrial and traffic emission source among the three pollution sources was 1.34 ng/m3. Coal combustion source displayed a downward trend. Ingestion was the main exposure pathway for REEs in PM2.5 for both children and adults. Ce contributed the most to the total intake of REEs in PM2.5 among the population, followed by La and Nd. The exposure risks of REEs in PM2.5 in the region were relatively low, but the trend of change was of great concern. It was strongly recommended to strengthen the concern about traffic-related non-exhaust emissions of particulate matter.

Accumulation and Translocation of Rare Trace Elements in Plants near the Rare Metal Enterprise in the Subarctic

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.

The rare-earth yttrium induces cell apoptosis and autophagy in the male reproductive system through ROS-Ca2+-CamkII/Ampk axis

China has the world's largest reserves of rare earth elements (REEs), but widespread mining and application of REEs has led to an increased risk of potential pollution. Yttrium (Y), the first heavy REEs to be discovered, poses a substantial threat to human health. Unfortunately, little attention has been given to the impact of Y on human reproductive health. In this study, we investigated the toxic effects of YCl3 on mouse testes and four types of testicular cells, including Sertoli, Leydig, spermatogonial and spermatocyte cells. The results showed that YCl3 exposure causes substantial damage to mouse testes and induces apoptosis and autophagy, but not pyroptosis or necrosis, in testicular cells. Genome-wide gene expression analysis revealed that YCl3 induced significant changes in gene expression, with Ca2+ and mitochondria-related genes being the most significantly altered. Mechanistically, YCl3 exposure induced mitochondrial dysfunction in testicular cells, triggering the overproduction of reactive oxygen species (ROS) by impairing the Nrf2 pathway, regulating downstream Ho-1 target protein expression, and increasing Ca2+ levels to activate the CamkII/Ampk signaling pathway. Blocking ROS production or Ca2+ signaling significantly attenuates apoptosis and autophagy, while supplementation with Ca2+ reverses the suppression of apoptosis and autophagy by ROS blockade in testicular cells. Notably, apoptosis and autophagy induced by YCl3 treatment are independent of each other. Thus, our study suggests that YCl3 may impair the antioxidant stress signaling pathway and activate the calcium pathway through the ROS-Ca2+ axis, which promotes testicular cell apoptosis and autophagy independently, thus inducing testicular damage and impairing male reproductive function.

Enrichment and distribution characteristics of heavy metal(loid)s in native plants of abandoned farmlands in sewage irrigation area

Soil samples and native plants were collected from abandoned farmlands with a long history of sewage irrigation along Dongdagou stream, Baiyin City. We investigated the concentrations of heavy metal(loid)s (HMMs) in soil-plant system to evaluate the accumulation and transportation ability of HMMs in native plants. Results indicated that soils in study area were severely polluted by Cd, Pb, and As. With the exception of Cd, the correlation between total HMM concentrations in soil and plant tissues was poor. Among all investigated plants, no one was close to the criteria for the HMM concentrations of hyperaccumulators. The concentrations of HMMs in most plants were reached the phytotoxic level and the abandoned farmlands could not be used as forages, which showed that native plants may possess resistance capabilities or high tolerance for As, Cu, Cd, Pb, and Zn. The FTIR (Fourier transform infrared spectrometer) results suggested that the detoxification of HMMs in plants may depend on the functional groups (-OH, C-H, C-O, and N-H) of some compounds. Bioaccumulation factor (BAF), bioconcentration factor (BCF), and biological transfer factor (BTF) were used to identify the accumulation and translocation characteristics of HMMs by native plants. S. glauca had the highest mean values of BTF for Cd (8.07) and Zn (4.75). C. virgata showed the highest mean BAFs for Cd (2.76) and Zn (9.43). P. harmala, A. tataricus, and A. anethifolia also presented high accumulation and translocation abilities for Cd and Zn. High HMMs (As, Cu, Cd, Pb, and Zn) accumulation in the aerial parts of plants may lead to increased accumulation of HMMs in the food chain; additional research is desperately required. This study demonstrated the HM enrichment characteristics of weeds and provided a basis for the management of abandoned farmlands.

Salinity and Heavy Metal Tolerance, and Phytoextraction Potential of Ranunculus sceleratus Plants from a Sandy Coastal Beach

The aim of the present study was to evaluate tolerance to salinity and different heavy metals as well as the phytoextraction potential of Ranunculus sceleratus plants from a brackish coastal sandy beach habitat. Four separate experiments were performed with R. sceleratus plants in controlled conditions: (1) the effect of NaCl gradient on growth and ion accumulation, (2) the effect of different Na⁺ and K⁺ salts on growth and ion accumulation, (3) heavy metal tolerance and metal accumulation potential, (4) the effect of different forms of Pb salts (nitrate and acetate) on plant growth and Pb accumulation. A negative effect of NaCl on plant biomass was evident at 0.5 g L^-1 Na⁺ and growth was inhibited by 44% at 10 g L^-1 Na⁺, and this was associated with changes in biomass allocation. The maximum Na⁺ accumulation (90.8 g kg^-1) was found in the stems of plants treated with 10 g kg^-1 Na⁺. The type of anion determined the salinity tolerance of R. sceleratus plants, as Na⁺ and K⁺ salts with an identical anion component had a comparable effect on plant growth: nitrates strongly stimulated plant growth, and chloride treatment resulted in slight but significant growth reduction, but plants treated with nitrites and carbonates died within 4 and 5 weeks after the full treatment, respectively. The shoot growth of R. sceleratus plants was relatively insensitive to treatment with Mn, Cd and Zn in the form of sulphate salts, but Pb nitrate increased it. Hyperaccumulation threshold concentration values in the leaves of R. sceleratus were reached for Cd, Pb and Zn. R. sceleratus can be characterized as a shoot accumulator of heavy metals and a hyperaccumulator of Na⁺. A relatively short life cycle together with a high biomass accumulation rate makes R. sceleratus useful for dynamic constructed wetland systems aiming for the purification of concentrated wastewaters.

Road traffic and abiotic parameters of underlying soils determine the mineral composition and nutritive value of the mushroom Macrolepiota procera (Scop.) Singer

The effectiveness of accumulating mineral elements by wild-growing mushrooms depends mainly on species, their growth place, and the underlying soil's chemical characteristics. The aim of the study was to determine the effect of road traffic and the role of chemical characteristics of soil on the mineral composition of Macrolepiota procera fruit bodies growing in close proximity to a road and an adjacent forest during a four-year period. The concentrations of the majority elements (mainly Al, Cd, Co, Cr, Cu, Pb, Ti, and Zn) in the soil near the road were significantly higher than those in the forest soil, which was reflected in the fruit bodies which contained a higher amount of these elements. While the accumulation of heavy metals and other elements in the M. procera fruit bodies did not depend on the total soil organic carbon content, the degree of their decomposition determined by the C:N ratio and the individual fractions of organic carbon had a significant influence. Our studies show that soil properties are highly variable in the natural habitats of M. procera, which affects the efficiency of element accumulation. Macrolepiota procera fruit bodies growing in soil with similar chemical properties were characterized by different mineral compositions. Moreover, the obtained results indicate that the fruit bodies of edible M. procera, not only those close to roads but also at a greater distance, may contain significant amounts of toxic As and Cd, which could pose a health risk if consumed. Although most studies describing the mineral composition of M. procera fruit bodies have found no evidence to question the safety of their consumption, this species can effectively accumulate selected elements when growing immediately beside roads or in their close proximity.

Distribution of rare earth elements (REEs) and their roles in plant growth: A review

The increasing use of rare earth elements (REEs) in various industries has led to a rise in discharge points, thus increasing discharge rates, circulation, and human exposure. Therefore, REEs have received widespread attention as important emerging pollutants. This article thus summarizes and discusses the distribution and occurrence of REEs in the world's soil and water, and briefly introduces current REEs content analysis technology for the examination of different types of samples. Specifically, this review focuses on the impact of REEs on plants, including the distribution and fractionation of REEs in plants and their bioavailability, the effect of REEs on seed germination and growth, the role of REEs in plant resistance, the physiological and biochemical responses of plants in the presence of REEs, including mineral absorption and photosynthesis, as well as a description of the substitution mechanism of REEs competing for Ca in plant cells. Additionally, this article summarizes the potential mechanisms of REEs to activate endocytosis in plants and provides some insights into the mechanisms by which REEs affect endocytosis from a cell and molecular biology perspective. Finally, this article discusses future research prospects and summarizes current scientific findings that could serve as a basis for the development of more sustainable rare earth resource utilization strategies and the assessment of REEs in the environment.

A critical review of phytoremediation for acid mine drainage-impacted environments

Acid mine drainage (AMD), a waste product of mining activities containing sulfates, iron and heavy metals, causes severe environmental degradation and pose risks to human health and sustainable development. Areas impacted by AMD are lacking remediation techniques that holistically address the ecologic, social, and economic needs of affected communities, for which phytoremediation is a promising solution. This review article introduces AMD and AMD-impacted environments and critically discusses phytomanagement, phytoprotection, and phytorestoration approaches towards AMD-impacted environments. Continued research and application of such approaches will help optimize resource and revenue-generating potentials, address biodiversity loss and carbon storage concerns of climate change, and promote sustainable agricultural management. With a focus on energy crops, phytomining critical elements, carbon storage, co-cropping, allelopathy, and ecosystem restoration, this review examines phytoremediation research that addresses positive economic and environmental opportunities for AMD-impacted environments.

Phytoextraction and recovery of rare earth elements using willow (Salix spp.)

Soil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix cultivars (Klara and Karin) were hydroponically exposed to different concentrations of six-REE for 4 weeks. The treatments were: T1 (Control: tap water), T2 (La: 50 mg/L) and T3 (La 11.50 + Y 11 + Nd 10.50 + Dy 10 + Ce 12 and Tb 11.50 in mg L^-1). The effects of the REE on Salix growth indicators (height, biomass, shoot diameter and root length), concentrations of REE in the produced biomass, and accumulation of REE in different parts of the Salix (stem, root, and leaf) tissues, were determined. In addition, the retention of REE in ashes following Salix combustion (800 and 1000 °C) was determined. The result indicates that with La and REE exposure, the height growth, dry biomass, shoot diameter and root length of all Salix remained equivalent to the control treatment excluding Klara, which displayed relatively higher growth in all parameters. Further, among the REE studied, the highest La concentration (8404 μg g^-1 DW) and La accumulation (10,548 μg plant^-1) were observed in Karin and Klara root respectively. Translocations and bioconcentration factors were discovered at <1 for all Salix, which indicates their phytostabilization potential. The total REE concentrations in bottom ashes varied between 7 and 8% with retention rates between 85 and 89%. This study demonstrates that Salix are suitable candidates for REE phytostabilization and the remediation of wastewater sites to limit metals percolating to the water layers in the ecosystem.

Trace Metal Contamination of Bottom Sediments: A Review of Assessment Measures and Geochemical Background Determination Methods

This paper provides an overview of different methods of assessing the trace metal (TM) contamination status of sediments affected by anthropogenic interference. The geochemical background determination methods are also described. A total of 25 papers covering rivers, lakes, and retention tanks sediments in areas subjected to anthropogenic pressure from the last three years (2019, 2020, and 2021) were analysed to support our examination of the assessment measures. Geochemical and ecotoxicological classifications are presented that may prove useful for sediment evaluation. Among the geochemical indices, several individual pollution indices (CF, Igeo, EF, Pi (SPI), PTT), complex pollution indices (PLI, Cdeg, mCdeg, Pisum, PIAvg, PIaAvg, PIN, PIProd, PIapProd, PIvectorM, PINemerow, IntPI, MPI), and geochemical classifications are compared. The ecotoxicological assessment includes an overview of Sediment Quality Guidelines (SQG) and classifications introduced nationally (as LAWA or modified LAWA). The ecotoxicological indices presented in this review cover individual (ERi) and complex indices (CSI, SPI, RAC, PERI, MERMQ). Biomonitoring of contaminated sites based on plant bioindicators is extensively explored as an indirect method for evaluating pollution sites. The most commonly used indices in the reviewed papers were Igeo, EF, and CF. Many authors referred to ecotoxicological assessment via SQG. Moreover, PERI, which includes the toxic response index, was just as popular. The most recognised bioindicators include the Phragmites and Salix species. Phragmites can be considered for Fe, Cu, Cd, and Ni bioindication in sites, while Salix hybrid cultivars such as Klara may be considered for phytostabilisation and rhizofiltration due to higher Cu, Zn, and Ni accumulation in roots. Vetiveria zizanoides demonstrated resistance to As stress and feasibility for the remediation of As. Moreover, bioindicators offer a feasible tool for recovering valuable elements for the development of a circular economy (e.g., rare earth elements).

A review of in situ phytoextraction of rare earth elements from contaminated soils

Rare earth elements (REE), with their distinct physical and chemical properties, are critical components of green economic development. Intensive exploitation and application of REE are wreaking havoc on the environment. But research on REE is still limited to a small number and in a few countries. With the growing interest of REE in modern technologies and their potential ecological risks, phytoextraction seems promising for both REE pollution reduction and resource circulation. This paper summarizes the recent findings in the literature concerning REE hyperaccumulating plants and relevant accumulation mechanisms. Additional interests should be focused on a broader range of plant species and a global scale to achieve a sustainable REE supply.Novelty statementThis paper summarized the referenced potential rare earth elements (REE) hyperaccumulator plants that accumulated higher than REE 100 µg/g and discussed their accumulation and translocation mechanisms.We addressed the synonyms of Dicranopteris pedata, Dicranopteris dichotoma Bernh., and Dicranopteris linearis.Although Dicranopteris pedata has been extensively studied in the sense of REE hyperaccumulation, active phytoextraction outside of its native range, as well as in accumulation of the precious heavy rare earth elements, may be difficult. Thus, further interests should take these disadvantages into account.

Interaction of traffic intensity and habitat features shape invasion dynamics of an invasive alien species (Ambrosia artemisiifolia) in a regional road network

Road corridors are important conduits for plant invasions, and an understanding of the underlying mechanisms is necessary for efficient management of invasive alien species in road networks. Previous studies identified road type with different traffic volumes as a key driver of seed dispersal and abundance of alien plants along roads. However, how the intensity of traffic interacts with the habitat features of roadsides in shaping invasion processes is not sufficiently understood. To elucidate these interactions, we analyzed the population dynamics of common ragweed (Ambrosia artemisiifolia L.), a common non-indigenous annual species in Europe and other continents, in a regional road network in Germany. Over a period of five years, we recorded plant densities at roadsides along four types of road corridors, subject to different intensities of traffic, and with a total length of about 300 km. We also classified roadsides in regard to habitat features (disturbance, shade). This allowed us to determine corridor- and habitat-specific mean population growth rates and spatial-temporal shifts in roadside plant abundances at the regional scale. Our results show that both traffic intensity and roadside habitat features significantly affect the population dynamics of ragweed. The combination of high traffic intensity and high disturbance intensity led to the highest mean population growth whereas population growth in less suitable habitats (e.g. shaded roadsides) declined with decreasing traffic intensity. We conclude that high traffic facilitates ragweed invasion along roads, likely due to continued seed dispersal, and can compensate partly for less suitable habitat features (i.e. shade) that decrease population growth along less trafficked roads. As a practical implication, management efforts to decline ragweed invasions within road networks (e.g. by repeated mowing) should be prioritized along high trafficked roads, and roadside with disturbed, open habitats should be reduced as far as possible, e.g. by establishing grassland from the regional species pool.

How polluted are cities in central Europe? - Heavy metal contamination in Taraxacum officinale and soils collected from different land use areas of three representative cities

The level of environmental contamination can vary according to different types of land use. The aim of the present study was to determine the relations among Cd, Pb, Ni and Cr content in plants (Taraxacum officinale) and soils for 10 types of land use in the urban areas of representative cities for central Europe region (Warsaw, Poznan and Wroclaw in Poland). Descriptive statistical analysis, as well as cluster analysis and principal component analysis, heatmaps and Andrews curves, was performed to identify relations between HMs and land use, as well as differences between particular cities. The investigations revealed variation among sites, plant organs and cities. The content (mg kg^-1 DW) in soils, roots and leaves for Cd varied between 0.4 and 3.6, 0.4-2.8 and 0.5-3.9, Cr ranged between 23.2 and 40.6, 14.0-26.1 and 15.8-24.8, Ni varied between 2.1 and 13.2, 0.2-42.1 and 0.0-3.9, while Pb varied between 27.0 and 231.5, 4.3-34.2 and 3.0-9.5, respectively. It was possible to note some tendencies. Nickel was the element with the highest content in the roots (up to 42.1 mg kg^-1 DW) in comparison to leaves and soils and the highest bioaccumulation factor (up to 15.0). This means that the main source of Ni might be contamination of the soil. The cluster analysis of standardized HM levels in leaves revealed that cadmium is a different from the other three elements, which might be related to the translocation factor, for which this element was found to have the highest levels at many sites.

Possible sources of rare earth elements near different classes of road in Poland and their phytoextraction to herbaceous plant species

The growing use of rare earth elements (REE) in industry determines their increased transport to the environment. The higher concentration of this group of elements in soils near roads may also suggest that traffic plays a significant role in their distribution. The aim of this study was to examine the content of REEs in selected consumables (car parts, asphalt) and environmental samples (plants, soils) in order to estimate the extent to which these elements derive from traffic and also to analyze their phytoextraction from soil by selected herbaceous plants species. Research materials were car parts (5 brake pads, 10 new tires - summer and winter), 20 samples of asphalt and road dust settled on its surface; soil, and 7 plants species growing at a distance of 1 m from the edge of the 5 roads located in the Wielkopolska Voivodeship, Poland. The content of REEs in the collected samples was determined using inductively coupled plasma optical emission spectrometer. The content of REEs in asphalt and brake pads was similar and significantly higher than in tires. According to the mass of particular stripped materials, the main source of these elements was asphalt. The amount of REEs released from tires to the environment was found to be much lower than REEs released from asphalt but generally higher than from brake pads. The content of REEs in the soil was found to increase in accordance with traffic intensity, but chemical composition of soil was the main determinant of the uptake these elements, mainly via the root systems of plants. The obtained results suggest that densely vegetated roadsides and verges could be an effective strategy for decontamination of soils polluted with REEs, although the most effective remedy would involve significant changes in the production technologies of automotive parts and asphalt that would limit the emission of elements to environment.

Solution structure of a europium–nicotianamine complex supports that phytosiderophores bind lanthanides

The structures of europium–EDTA (known lanthanide chelator) and europium–nicotianamine (biochemical precursor of phytosiderophores) complexes are resolved, in solution, with ab initio molecular dynamics as well as excitation and emission spectroscopy.

Plant Biosystems Design Research Roadmap 1.0

Human life intimately depends on plants for food, biomaterials, health, energy, and a sustainable environment. Various plants have been genetically improved mostly through breeding, along with limited modification via genetic engineering, yet they are still not able to meet the ever-increasing needs, in terms of both quantity and quality, resulting from the rapid increase in world population and expected standards of living. A step change that may address these challenges would be to expand the potential of plants using biosystems design approaches. This represents a shift in plant science research from relatively simple trial-and-error approaches to innovative strategies based on predictive models of biological systems. Plant biosystems design seeks to accelerate plant genetic improvement using genome editing and genetic circuit engineering or create novel plant systems through de novo synthesis of plant genomes. From this perspective, we present a comprehensive roadmap of plant biosystems design covering theories, principles, and technical methods, along with potential applications in basic and applied plant biology research. We highlight current challenges, future opportunities, and research priorities, along with a framework for international collaboration, towards rapid advancement of this emerging interdisciplinary area of research. Finally, we discuss the importance of social responsibility in utilizing plant biosystems design and suggest strategies for improving public perception, trust, and acceptance.

Capability of Secale montanum trusted for phytoremediation of lead and cadmium in soils amended with nano-silica and municipal solid waste compost

The purpose of this study is to evaluate the capability of Secale montanum trusted for phytoremediation of contaminated soils with lead (Pb) and cadmium (Cd). To conduct this study, soil samples were taken from contaminated rangelands soils around National Lead & Zinc Factory, Zanjan, Iran. In this study, which was performed in a greenhouse, after preparing the pot and treating soils with nano-silica (NS) and municipal solid waste compost (MSWC) amendments, 20 Secale seeds were cultured in each pot. The translocation factor (TF), the bio-concentration factor (BCF), and remediation factor (RF) were calculated to determine the phytoremediation capability of Secale. Six months after establishment, plant organs were harvested and Pb and Cd concentrations were measured in shoot and roots of Secale. For statistical analysis and to compare the obtained means, ANOVA and Tukey's tests were performed, respectively. The pot experiment results showed that Pb uptake and accumulation by roots of S. montanum were highest in pots amended with NS500. In comparison, Pb concentration in shoots of Secale was highest in pots amended with MSWC 2%. In general, it seems that NS500 and MSWC 2% help phytoremediation capability of Secale in the Pb-contaminated soils.

Differential exposure to 33 toxic elements through cigarette smoking, based on the type of tobacco and rolling paper used

Environmental pollution due to various elements is increasing all across the planet owing to their use in industrial processes. The tobacco plants and the vegetables used in the manufacturing of smoking paper may accumulate these elements from the environment. Thus, tobacco and smoking paper may be relevant contributors among the content of elements in cigarettes, including some emerging pollutants such as rare earth elements (REEs). Thirty-two elements related to hi-tech industrial processes were analyzed in tobacco, rolling paper, and filters (n = 257 samples) by ICP-MS. A variety of industrial brands and "roll-your-own" cigarette papers were considered. The potential maximum daily exposure to these elements by a hypothetical heavy smoker was calculated for each type of cigarette. We found significant differences in the levels of most elements, both in the tobacco and in the paper. Black tobacco cigarettes contained the maximum levels. We found that the paper used in roll-your-own cigarettes may significantly modify their concentration of elements. Fast-burning, bleached, and flavored papers also contribute to higher levels of these pollutants. Thus, the differences in theoretical exposure depending on the type of cigarette consumed-either branded or hand-rolled-may be very striking, of up to 35-40 times. In addition to the number of cigarettes consumed per day, it is necessary to consider the type of cigarette consumed to assess the risk of exposure to toxic elements. Tobacco paper is a prominent source of exposure to toxic elements. Cigarette smoke is another source of exposure to emerging contaminants such as REE.

Relationship between concentration of rare earth elements in soil and their distribution in plants growing near a frequented road

Rare earth elements (REEs) are a group of elements whose concentration in numerous environmental matrices continues to increase; therefore, the use of biological methods for their removal from soil would seem to be a safe and reasonable approach. The aim of this study was to estimate the phytoextraction efficiency and distribution of light and heavy (LREEs and HREEs) rare earth elements by three herbaceous plant species: Artemisia vulgaris L., Taraxacum officinale F.H. Wigg. and Trifolium repens L., growing at a distance of 1, 10, and 25 m from the edge of a frequented road in Poland. The concentration of REEs in soil and plants was highly correlated (r > 0.9300), which indicates the high potential of the studied plant species to phytoextraction of these elements. The largest proportion of REEs was from the group of LREEs, whereas HREEs comprised only an inconsiderable portion of the REEs group. The dominant elements in the group of LREEs were Nd and Ce, while Er was dominant in the HREEs group. Differences in the amounts of these elements influenced the total concentration of LREEs, HREEs, and finally REEs and their quantities which decreased with distance from the road. According to the Friedman rank sum test, significant differences in REEs concentration, mainly between A. vulgaris L., and T. repens L. were observed for plants growing at all three distances from the road. The same relation between A. vulgaris L. and T. officinale was observed. The efficiency of LREEs and REEs phytoextraction in the whole biomass of plants growing at all distances from the road was A. vulgaris L. > T. officinale L. > T. repens L. For HREEs, the same relationship was recorded only for plants growing at the distance 1 m from the road. Bioconcentration factor (BCF) values for LREEs and HREEs were respectively higher and lower than 1 for all studied plant species regardless of the distance from the road. The studied herbaceous plant species were able to effectively phytoextract LREEs only (BCF > 1); therefore, these plants, which are commonly present near roads, could be a useful tool for removing this group of REEs from contaminated soil.

Heavy metal contents and enrichment characteristics of dominant plants in wasteland of the downstream of a lead-zinc mining area in Guangxi, Southwest China

A field investigation on the content of heavy metals in soils and 17 kinds of dominant plants from wasteland of the downstream of a Pb-Zn mine in Northwest Guangxi Zhuang Autonomous Region was carried out. The absorption and accumulation characteristics of heavy metals between plants and soil were compared, and the candidate species for ecosystem restoration of the area were selected. The results indicated that the soils had been subjected to pollution of heavy metals in varying degrees. The concentrations of Cd, Pb, Zn were 46.5, 57.3 and 23.7 times higher than their corresponding background values, respectively. The contents of Cd, Pb and Zn in the most analyzed plants exceed the normal ranges and the phytotoxic level. C. crepidioides, S. nigrum, B. pilosa, C. Canadensis, A. conyzoides, I. denticulata and E. crusgali showed strong capability in accumulation and transport of Cd, and they could be used as good candidates for Cd- phytoextraction. Among which, Cd concentration in the aerial part of C. crepidioides exceeded the threshold of Cd-hyperaccumulator. Thus, C. crepidioides demonstrated the basic characteristics of a Cd-hyperaccumulator. The lower translocation ratios for Cd, Cu, Zn and Pb in P. vittata and C. chinensis make them suitable for phytostabilization in the study area.