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Acute and chronic arsenic (As) toxicity is a global health issue affecting millions of people, which leads to inactivation of over 200 enzymes, particularly those involved in cellular energy pathways and DNA synthesis and repair. The fern Pteris vittata acts as a hyperaccumulator of As and may be useful for phytoremediation to reduce disposal risks by utilizing metal-enriched plant biomass in energy and metal recovery. However, these ferns grow in limited environments and its transplantation and transport can be challenging. Therefore, we generated a transgenic Arabidopsis plant as a seed plant model, capable of accumulating As in their vacuole lumen. This was achieved by transforming the As-resistant bacterial As transporter, ArsB, via fusion with a organelle-targeting signal to the vacuolar membrane, N-ethyl-maleimide-sensitive factor attachment protein receptors (SNAREs) protein, VAMP711. In this study, we developed the iVenus assay as a method for detecting whether the N- or C-terminus of a membrane protein is located on the cytoplasmic or exoplasmic side, and from the result of the iVenus assay, we generated the transgenic plant introduced N-terminal end of ArsB with VAMP711, localized to the central vacuolar membrane to accumulate As in the shoot and differentiation zone of root.

The hydrothermal liquefaction (HTL) of As enriched Pteris vittata L. (PVL, hyper-accumulator biomass) was performed with the recycled aqueous phase as reaction medium, aiming to dispose the biomass with high water content and produce high-quality bio-oil. After three times of aqueous phase recycling at 275 °C, 30 min, the bio-oil yield increased to 30.32% from 21.54% and the higher heating value (HHV, 28.51 MJ/kg) of the bio-oil was higher than that of the bio-oil from HTL with pure water (26.80 MJ/kg). The main compounds detected in bio-oils were phenols, ketones, hydrocarbons, and aldehydes. Acetic acid (17.21–24.77 mg/mL) was dominant in the aqueous phases, resulting in the low pH (4.31–4.89). The heavy metals (Cu, Pb, Zn, Cd) mainly remained in bio-char whereas As was transferred to aqueous phase. Thus, HTL by aqueous phase recycling could be a promising way for PVL treatment to obtain high-quality bio-oil and arsenic recovery.

This study investigated the concentrations of 22 elements in two Turin urban soils located in the city center (Campana Street garden (CA)) and in a peripheral area (Nobile Park (NOB)). The former was found contaminated by Pb, Zn, Ba, Cr and Ni and, to a lower degree, by As, Co, Cu and Cd, while the latter showed high concentrations of Co, Cr and Ni. The nature of Cr, Ni and Co in both sites is mainly geogenic, whereas the high content of Pb, Zn, Ba, As, Cu and Cd in the CA soil is probably due to exposure to atmospheric deposition linked to emissions from motor vehicles, domestic and industrial burning of fossil fuels and industrial emissions. We evaluated the uptake of potentially toxic elements (PTEs) by four plant species suitable for phytoremediation (Brassica juncea, Helianthus annuus, Zea mays and Pteris vittata) in controlled conditions in CA and NOB soils in order to assess their efficiency in the absorption of PTEs and suitability to restore the CA site. Results highlighted a different uptake ability of the plants according to the considered element, for example, Brassica juncea demonstrated a great capability in cadmium uptake. The effect of a soil improver, derived from the composting of green and organic waste, on absorption efficiency was also studied and it altered uptake preferences of specific elements by the tested plant species, thus suggesting that its use has to be evaluated according to the target.

In view of the uneven artificial sowing, low sowing, as well as the fact that the existing seeders cannot meet the sowing requirements of Pteris vittata, this paper designed an automatic plug seeder by using the method of spraying and sowing after mixing spores and water. In order to obtain the optimum working parameters of the seeder, response surface method (RSM) was employed to design the experiments and evaluate the results with the purpose of optimizing parameters for improving spraying uniformity. The parameters such as the distance between the nozzle and plug and the nozzle angle and transmission speed were selected, and then the regression equation of spraying uniformity was established. The results showed that the influence of various factors on spraying uniformity coefficient from high to low were nozzle angle, distance between the nozzle and plug and transmission speed. Through the experimental analysis, it can be concluded that when the distance between the nozzle and plug was 11.63 cm, the nozzle angle and the transmission speed were 79.23° and 0.21 m/s, respectively; the seeding uniformity coefficient was the largest, 83.43%. The verification test results indicated that the optimized result was reliable. This study can provide reference for the development of micro seed seeder.

Phytoremediation is a promising inexpensive method of detoxifying arsenic (As) contaminated soils using plants and associated soil microorganisms. The potential of Pteris vittata to hyperaccumulate As contamination has been investigated widely. Since As(V) is efficiently taken up by P. vittata than As(III), As speciation by associated rhizobacteria could offer enormous possibility to enhance As phytoremediation. Specifically, increased rhizobacteria mediated As(III) to As(V) conversion appeared to be a crucial step in As mobilization and translocation. In this study, Pseudomonasvancouverensis strain m318 with the potential to improve As phytoremediation was inoculated to P. vittata in a field trial for three years to evaluate its long-term efficacy and stability for enhancing As phytoextraction. The biomass, As concentration, and As accumulation of ferns showed to be increased by inoculation treatment. Although this trend occasionally declined which may be accounted to lower As concentration in soil and amount of precipitation during experiments, the potential of inoculation was observed in increased enrichment coefficients. Further, the arsenite oxidase (aioA-like) genes in the rhizosphere were detected to evaluate the influence of inoculation on As phytoremediation. The findings of this study suggested the potential application of rhizosphere regulation to improve phytoremediation technologies for As contaminated soils. However, the conditions which set the efficacy of this method could be further optimized.

The release of potentially toxic metal(loid)s (PTMs) such as As, Cd, Cr, Pb and Hg has become a serious threat to the environment. The anthropogenic contribution of these PTMs, especially Hg, is increasing continuously, and coal combustion in thermal power plants (TPPs) is considered to be the highest contributor of PTMs. Once entered into the environment, PTMs get deposited on the soil, which is the most important sink of these PTMs. This review centred on the sources of PTMs from coal and flyash and their enrichment in soil, chemical behaviour in soil and plant, bioaccumulation in trees and vegetables, health risk and remediation. Several remediation techniques (physical and chemical) have been used to minimise the PTMs level in soil and water, but the phytoremediation technique is the most commonly used technique for the effective removal of PTMs from contaminated soil and water. Several plant species like Brassica juncea, Pteris vittata and Helianthus annuus are proved to be the most potential candidate for the PTMs removal. Among all the PTMs, the occurrence of Hg in coal is a global concern due to the significant release of Hg into the atmosphere from coal-fired thermal power plants. Therefore, the Hg removal from pre-combustion (coal washing and demercuration techniques) coal is very essential to reduce the possibility of Hg release to the atmosphere.

A comparative evaluation of arsenic (As)-induced toxicity has been made in selected Western Himalayan ferns belonging to the family Pteridaceae (Pteris vittataL. andP. creticaL.) and Polypodiaceae (Polypodiodes microrhizoma(C. B. Clarke ex Baker) Ching andLepisorus contortus(H. Chirst) Ching) employing a rapid leaf (pinna) slice test. The exposure of pinna segments to As(V) (Na2HAsO4; 0-1000 mu M), led to a concentration-dependent increase in K(+)leakage into the incubation medium owing to membrane damage. Strong species-specific differences were evident. Thus, the magnitude of K(+)leakage enhancement was much lower in Pteridaceae members (lowest inP. vittata) than in those of Polypodiaceae. The As effects were like those of Cu, a redox active element like As, and H(2)O(2)suggesting them to be mediated by oxidative stress. Involvement of K(+)channels in As-induced K(+)leakage is unlikely, as no effect of tetraethylammonium chloride (TEA), a K(+)channel inhibitor was evident. Furthermore, the activities of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were markedly altered due to As treatment in a species-specific manner pointing to a role of antioxidant defence in differential response and thereby tolerance of the concerned ferns to As. Findings have implications for phytoremediation.

Arsenic (As) contaminated soil is a major issue in China. The discovery of As hyperaccumulator Pteris vittata L. opens a door for the phytoextraction of arsenic contaminated soils. The phytoremediation technology includes selecting proper P. vittata ecotype, reproduction and transplantation of P. vittata sporelings, fertilizer and chemical amendments, harvest and disposal. Depending on the local environmental conditions, scenarios for the irrigation, harvest time and frequency, and the disposal of As-enriched biomass were established. During field practices, the germination and cultivation of P. vittata sporelings, and the safe disposal of As–enriched P. vittata biomass were identified as essential processes. Therefore, fast reproduction technology of P. vittata sporeling, and safe incineration technology were paid focused attention. Furthermore, strengthening measures for the As phytoremediation technologies were proposed from the aspects of fertilizer application, harvest frequency, and ecotype selection. Finally, the biogeochemical cycles of As in the phytoremediation system was compared with the system with normal plants growing. It indicated that the application of phytoremediation led to an As net output of 7.02 kg ha−1 A−1, while on the field with normal plant growing, As was accumulating in soil at a rate of 0.24 kg ha−1 A−1.

In situ phytoextraction projects using Pteris vittata have been established with high removal rates of As. The first phytoextraction project in the world was established in Chenzhou of Hunan Province. Afterwards, more phytoextraction projects were established in Guangxi Zhuang Autonomous Region, Yunnan Province, and Henan Province. Through the phytoremediation practices, phytoremediation is confirmed to be an economical, easy and green technology, which well fit for the current farmland contamination status. Besides, the strengthening measures have expanded the application range of phytoextraction from south China to North China. And the utilization of this technology is not limited to farmland but also works for the brown sites. However, there are still a lot of questions waiting for further study. These questions proposed new demands for the science and technology development of phytoremediation technology.

In this study, the relationship between heavy metals (HMs) concentrations in soils and several weeds including Cyclosorus parasiticus, Dicranopteris linearis, Pityrogramma calomelanos, and Pteris vittata in three mining sites (Cam Gia (Thai Nguyen city), Tan Long (Dong Hy district), and Ha Thuong (Dai Tu district)) in Thai Nguyen province, Vietnam, have been investigated. The levels of HMs varied among soil origins and showed the contaminations of As, Cu, and Pb in soil samples collected in Dong Hy and Dai Tu districts. In addition, the HM distribution and cocontamination phenomena in different soils significantly affected the HM residues and transportation abilities into different species as well as tissues. Moreover, based on the analysis of bioaccumulation factor (BF) and translocation factor (TF), C. parasiticus and D. linearis were found potentially for phytoextraction by roots, while P. calomelanos and P. vittata were suitable for hyperaccumulation in shoots and leaves. Consequently, the strongest antioxidant property by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and superoxide anion (SRSA) radical scavenging assays were demonstrated in the methanol root extracts of C. parasiticus and P. vittata, respectively. In conclusion, the correlation among HM in soils and tissues with antioxidant property allows us to hypothesize that the presence of these elements can enhance the antioxidant activity of plant extracts, suggesting to apply the weeds in phytoremediation as well as in phytomedicine.

The arsenic (As) phytoremediation technology, based on the As hyperaccumulating ability of Pteris vittata, has been applied to more than 20 phytoremediation projects, achieving different levels of remediation efficiencies. However, currently, there are no commonly accepted evaluation methods of phytoremediation efficiency. The decrease in soil As concentration, the accumulation of As in hyperaccumulating plants, and the bioavailability of As in soil are factors to be considered. This chapter briefly introduced the application of these three indexes to the evaluation of phytoremediation efficiency. Recently, it has been further proposed that the remediation of agricultural soil should also take sustainability into consideration. Therefore, further study is needed to establish a streamline for a comprehensive evaluation of phytoremediation efficiency.

Les auteurs signalent une observation de Pteris vittata L. dans la Numidie algérienne. Cette découverte permet de faire le point sur sa répartition en Algérie.

The mechanism for arsenic (As) uptake by the hyperaccumulator Pteris vittata and its ability to tolerate high As concentrations is an active research field. The potential As hyperaccumulation mechanisms of P. vittata was summarized from the aspects of the distribution and transformation of As in P. vittata, the relationship between As and phosphorus (P), the driving force for the As translocation upwards, and the compartmentalization and chelation of As in P. vittata. It has been identified that the synergic absorption of As and P, the reduction of As in the endodermis of rhizoid, transportation-driven translocation upwards, and the compartmentation of As in trichrome, and the chelation of As with sulfur have contributed to the efficient hyperaccumulation of As by P. vittata. Besides, As is a redox-sensitive element whose toxicity largely depends on its oxidation state and chemical speciation. Synchrotron radiation based X-Ray technologies provide an advanced tool to accurately reflect the existence form and the transferring process.

An innovative approach, based on hyperspectral imaging (HSI) coupled with chemometrics, allowing the detection of arsenic (As) in the hyper-accumulator fern Pteris Vittata L., is presented in this study. The aim of this work was to investigate the possibility of monitoring by HSI the As sequestration capacity of plants grown on As-contaminated soils, in order to perform soil remediation. The proposed approach is based on the acquisition by HSI in the SWIR range (1000-2500 nm) of fern leaves, followed by the implementation of a classification model based on Partial Least Square Discriminant Analysis (PLS-DA). Following this procedure, false color maps, representative of the chemical elements distribution on the leaves were obtained, where As is clearly detected without performing any chemical analysis. The proposed approach is not invasive and not destructive. Comparative evaluations were carried out analyzing Pteris Vittata L. leaves collected from plants grown on natural soils containing different As concentrations. To evaluate reliability, robustness and analytical correctness of the proposed HSI approach, micro X-ray fluorescence (μXRF) analyses were carried out on the same samples in order to quantitatively and topologically assess As presence in the leaves of the plants. The achieved results are very promising for monitoring the phytoremediation process by detecting and controlling the uptake of As plants growing on contaminated soils.

Identifying the inflection points and main influencing factors for arsenic (As) accumulation in Pteris vittata L. under field conditions is important to improve the phytoremediation efficiency. In this study, data on the entire growth cycle (270 days) of P. vittata over a year were recorded through a field trial. The results showed that the As accumulation characteristics of P. vittata were obviously different from those observed in greenhouse experiments. The aboveground biomass of P. vittata began to stabilize on day 180; the As concentration increased to a peak on day 90 and subsequently declined until day 180. The As accumulation was 318.11 g/hm2 after 120 days, reaching 96.7% of the highest value predicted by the logistic model. The results indicated that soil humidity is the key influencing factor for As accumulation by P. vittata. Increasing the soil humidity can substantially improve the As extraction efficiency. Based on the results of As accumulation in P. vittata, it could be suggested that the effect of As efflux on P. vittata was not significant. According to theoretical calculations, the total As loss caused by rainfall leaching accounted for less than 2.2% of the total As accumulation. The parameters obtained herein are significant for guiding the remediation of As-contaminated soils under similar climatic conditions.

Developing P-efficient plants helps improve P uptake from soils with low-available P and reduce environmental damage by P runoff. Here, we investigated a novel root-specific phytase PvPHY1 from As-hyperaccumulator Pteris vittata, which can efficiently utilize phytate, a recalcitrant organic phosphorus in soil. Unlike other plants, expression of PvPHY1 in P. vittata was greater in the roots than the fronds. A pure phytase with considerable activity was obtained via prokaryotic expression. Expressing PvPHY1 in tobacco (PvPHY1-Ex) enhanced its growth (2.8 to 3.5–3.9 g per plant) and increased its P accumulation by 10–50% under low- and adequate-P conditions. Further, PvPHY1-Ex tobacco showed 25–32% lower intracellular phytate and 30–56% higher inorganic P in the roots, likely due to phytase-mediated hydrolysis of phytate. Decrease of phytate levels up-regulated phosphate transporter genes (NbPht1;1, NbPht1;2 and NbPht1;6), leading to greater P and As uptake. However, As translocation to the shoots was low, probably due to competition from increased inorganic P via phytate hydrolysis. As such, PvPHY1 facilitated P uptake from soils and phytate hydrolysis in plants, thereby promoting tobacco growth. Overall, PvPHY1 from P. vittata helps better understand the novel phytase to increase soil P utilization efficiency, thereby reducing P fertilizer requirements for crop production.

As-enriched Pteris vittata L. (PVL, a kind of hyper-accumulator biomass) was converted into high-quality biofuel by the catalytic hydrogenolysis, aiming to achieve effective treatment and high-value utilization of hyper-accumulators. After pretreatment of PVL to remove lipids and lignin, more than 64% of heavy metals were transferred into water, and the As content in the solid biomass was reduced from 1328 mg/kg to 483 mg/kg. The multifunctional catalysts RhCl3/NaI/HCl/H2 were used in a biphasic reaction system to convert PVL into biofuel with high selectivity. The main products are C5 and C6 furans and low oxygen content ketones, which have a high heating value (HHV) and can be directly used as biofuel. The highest yields of C5 and C6 products were obtained with 60.2% and 61.1% (based on the corresponding hemicellulose and cellulose) under the optimal reaction conditions (160 °C, 4 h, 300 psi H2, 4 mmol NaI, H2O/toluene = 1:1). The total biofuel yield based on dry PVL was 18.8 wt.%. After the reaction, more than 50% heavy metals (Cu, Pb, Zn, Cd, As) remained in the bio-char, while the heavy metals in the biofuel were less than 20% (As content was less than 55 mg/kg). Therefore, catalytic hydrogenolysis was perceived as a promising technique for PVL treatment to obtain high-quality biofuel and arsenic recovery.

In this paper, we report ecological and environmental investigations on Pteris vittata in the As–Pb–Hg-polluted Bone River area, Gorontalo Province, Indonesia. The density distribution of P. vittata decreases from around the artisanal and small-scale gold mining (ASGM) site to the lower reaches of the Bone River, and it is rarely found near Gorontalo City. The maximum concentrations of As, Hg, and Pb recorded in the soil samples were 401, 36, and 159 mg kg−1, respectively, with their maximum concentrations in P. vittata recorded as 17,700, 5.2, and 39 mg kg−1, respectively. Around the ASGM sites, the concentrations of As, Pb, and Hg in P. vittata were highest in the study area. These data suggest that P. vittata, a hyperaccumulator of As, may be useful as a bioindicator for assessing environmental pollution by Pb and Hg.

Phytoextraction using hyperaccumulator, Pteris vittata, to extract arsenic (As) from soil has been applied to large areas to achieve an As removal rate of 18% per year. However, remarkable difference among different studies and field practices has led to difficulties in the standardization of phytoextraction technology. In this study, data on As concentration in P. vittata and related environmental conditions were collected through literature search. A conceptual framework was proposed to guide the improvement of phytoextraction efficiency in the field. The following influencing factors of As concentration in this hyperaccumulator were identified: total As concentration in soil, soil available As, organic matter in soil, total potassium (K) concentration in soil, and annual rainfall. The geodetection results show that the main factors that affect As concentration in P. vittata include soil organic matter (q = 0.75), soil available As (q = 0.67), total K (q = 0.54), and rainfall (q = 0.42). The predictive models of As concentration in P. vittata were established separately for greenhouse and field conditions through multivariate linear stepwise regression method. Under greenhouse condition, soil available As was the most important influencing factor and could explain 41.4% of As concentration in P. vittata. Two dominant factors were detected in the field: soil available As concentration and average annual rainfall. The combination of these two factors gave better prediction results with R2 = 0.762. The establishment of the model might help predict phytoextraction efficiency and contribute to technological standardization. The strategies that were used to promote As removal from soil by P. vittata were summarized and analyzed. Intercropping with suitable plants or a combination of different measures (e.g., phosphate fertilizer and water retention) was recommended in practice to increase As concentration in P. vittata.

Pot experiments were conducted to assess the effects of monoammonium phosphate (NH4H2PO4) and citric acid (CA) on the arsenic uptake of Chinese brake fern (Pteris vittata L. in two typical arsenic-...

While phosphate (P) inhibits arsenic (As) uptake by plants, phytate increases As uptake by As-hyperaccumulator Pteris vittata. Here we tried to understand the underling mechanisms by investigating the roles of phytate in soil As desorption, P transport in P. vittata, short-term As uptake, and plant growth and As accumulation from soils. Sterile soil was used to exclude microbial degradation on phytate. Results showed that inorganic P released 3.3-fold more As than that of phytate from soil. However, P. vittata accumulated 2–2.5 fold more As from soils with phytate than that in control and P treatment. In addition, different from P suppression on As uptake, solution uptake experiment showed that As uptake in phytate treatment was comparable to that of control under 0.1–7.5 μM As after 1–24 h. Moreover, responding to phytate, P. vittata P transporter PvPht1;3 increased by 3-fold while PvPht1;1 decreased by 65%. The data suggested that phytate upregulated PvPht1;3, thereby contributing to As uptake in P. vittata. Our results showed that, though with lower As release from soil compared to P, phytate induced more As uptake and better growth in P. vittata by upregulating P transporters.

This study aimed to investigate the Sb and As co-accumulating processes of Pteris vittata under soil culture condition, including the transformation of Sb and As, and the difference in co-accumulating ability among different plant species/populations. Two populations of P. vittata and one population of As-tolerant species Holcus lanatus L. were grown on soil co-contaminated by Sb and As. Sb and As speciation in plants was assessed by X-ray absorption near-edge structure (XANES) spectroscopy. P. vittata displayed strong As- but limited Sb-accumulating ability, with the highest shoot concentrations of As and Sb reaching 455 and 26 mg kg−1, respectively. After 28 days culture, the concentrations of Sb and As in the soil solution were reduced by up to 22% and 36% in the P. vittata treatments, respectively. Holcus lanatus showed limited uptake for both metalloids. In P. vittata, the reduction of arsenate to arsenite occurred (with As in shoots all existing as arsenite), but limited reduction of antimonate to antimonite (with more than 90% of Sb in shoots existing as antimonate) was observed. In terms of the differences in metalloid uptake between the two P. vittata populations, the population from the habitat with higher soil As concentration showed 35% higher As uptake than the population from the habitat with lower As concentration. This populational difference may partly result from varying As transformation efficiencies. However, no significant difference was observed in Sb accumulation between the two populations.

Mobility of toxic metals, originating from natural or anthropogenic sources, from soil to groundwater is a matter of utmost concern to human health. Remediation of the contaminated groundwater is of the highest priority as groundwater is an alternate source of freshwater that is used all over the world for drinking purpose. Hence, in the present study, Pteris vittata L. is used as a simple, biodegradable and efficient biosorbent of toxic metals in its non-living and pelletized form by employing organic binders and a simple manual pellet press. The capacity of the pelletized Pteris vittata L. to sequester the metals Cd(II) and Cr(VI) from an aqueous solution is determined through the study on the effect of operating conditions, isotherm and kinetic models. The metal removal capacity of the biosorbent pelletized using corn starch as the binder is 13.51 mg/g for Cd(II) at pH 6 and 1.66 mg/g for Cr(VI) at pH 2 as obtained from the Langmuir isotherm model. The diffusion of the metal ions into the micropores of the pellets aids its biosorption. Physical adsorption, ion exchange, covalent bonding and complexation are deduced to be few of the biosorption mechanisms involved. The findings contribute to the existing data in the biosorption technology. The novelty lies in the use of a weedy fern, Pteris vittata L., pelletized with desired structural characteristics as a potential low-cost biosorbent of toxic metals from groundwater.

Hyperaccumulator biomass, as a promising resource for renewable energy that can be converted into valuable fuel productions with high conversion efficiency, must be considered as hazardous materials and be carefully treated before further reuse due to the high contents of heavy metals. In this study, Pteris vittata L., an As-hyperaccumulator biomass was treated by an effective and environmental friendly method-supercritical water gasification (SCWG) using a bench-scale batch reactor. The contents of heavy metals (Cd, Pb and Zn) and arsenic metalloid in solid, liquid and gaseous products during SCWG process were thoroughly investigated. The speciation fractions including exchangeable, reducible, oxidizable and residual fractions of each heavy metal as the proportion of the total contents in solid residue were presented and the transformations trend of these heavy metals during the SCWG process was especially demonstrated. The significant operating parameters, including reaction temperature (395–445 °C), pressure (21–27 MPa) and residence time (0–40 min) were varied to explore their effects on the contents and forms. Moreover, the environmental risks of heavy metals in solid residues were evaluated based on risk assessment code, taking into consideration the speciation fractions and bioavailability. It was highlighted that although heavy metals particularly Pb and Zn tended to accumulate in solid residues with a maximum increment of about 50% in the total content, they were mostly converted to more stable oxidizable and residual fractions, and thus the ecotoxicity and bioavailability were greatly mitigated with no obvious increase in direct toxicity fractions. Each tested heavy metal presented no or low risk to the environments after SCWG treatments, meaning that the environmental pollution levels were markedly reduced with no or low risk to the environment. This study highlights the remarkable ability of SCWG for the heavy metal stabilization.

In this study, multiple types of samples, including soils, plants, litter and soil invertebrates, were collected from a former arsenic (As) mine in China. The total As concentrations in the soils, earthworms, litter and the aboveground portions of grass from the contaminated area followed the decreasing order of 83-2224 mg/kg, 31-430 mg/kg, 1-62 mg/kg and 2-23 mg/kg, respectively. X-ray absorption near-edge structure (XANES) analysis revealed that the predominant form of As in the soils was arsenate (As(V)), while no arsenite (As(III)) was detected. In the grass and litter of the native plant community, inorganic As species (As(V) and As(III)) were the main species, while minor amounts of DMA, MMA, AsC, and an unknown As species were also detected in the extracts analyzed with high-performance liquid chromatography inductively coupled plasma mass spectrometry (HPLC-ICP-MS). The As speciation and As concentrations varied with the plant species, and very high As levels (197-584 mg/kg) and proportions of inorganic As (99%) were found in two As-hyperaccumulating ferns, Pteris vittata and Pteris cretica. The major As species extracted from earthworms were inorganic, with proportions of 51-53% As(III) and 38-48% As(V). AsB was the only organic species present in the earthworm samples, although at low proportions (8.99%). The internal bioconversion of other As species is hypothesized to contribute greatly to the formation and accumulation of AsB in earthworms, although the direct external absorption of organic As from soils might be another source. This study sheds light on the potential sources of complex organoarsenicals, such as AsB, in terrestrial organisms.

Soils used for rice (Oryza sativa L.) cultivation in some areas contain high concentrations of arsenic (As) due to irrigation with groundwater containing As and intensive use of agrochemicals or industrial residues containing As. To restrict rice uptake of As in these soils, approaches to reduce As input and bioavailability must be considered. One approach to reduce As input into rice soils or uptake by rice is cultivating rice under aerobic, intermittent flooding, or alternate wetting and drying (AWD) conditions, rather than in submerged soils, or use of irrigation water low in As. For reducing As bioavailability in soil, aerobic or AWD rice culture and application of biochar, sulfur (S), and/or rice polish to soil are promising. Moreover, use of As-hyperaccumulating plant species (e.g., Pteris vittata L.) in rotation or combinations with favourable plant species (e.g., Azolla, Chlorella, or Nannochloropsis species) can also be promoted, in addition to using rice cultivars that are tolerant to As. Though applications of high doses of phosphorus (P), iron (Fe), and silicon (Si) fertilizers have shown promise in many instances, these methods have to be practiced carefully, because negative effects have also been reported, although such incidents are rare. Major factors affecting As speciation and bioavailability in soil are chemical properties such as redox status, pH, and Fe, P, Si, and S concentrations, physical properties such as texture and organic matter, and biological properties such as methylation activity by soil microorganisms. However, as many of these factors interact, long-term examination under field conditions is needed before measures are recommended for and implemented in farmers' fields.

This study examined the effects of P. vittata and a polycyclic aromatic hydrocarbon (PAH)-degrading bacterium (Alcaligenes sp.) on arsenic (As) uptake and phenanthrene dissipation. Bacterial inoculation substantially increased As accumulation in plants by 27.8% (frond) and 27.5% (root) at 60 d, respectively, compared with the non-inoculated treatment, although temporal change of As translocation and reduction in plants was observed. Bacterial inoculation positively affected plants by improving growth, nutrition and antioxidative activities, and helped to modify soil As availability to the plants, which may benefit in plant tolerance and As accumulation. Plant and bacteria association enhanced phenanthrene dissipation from the soil, with the highest dissipation rate of 96.4% at 60 d in the rhizosphere, which might be associated with enhanced bacterial population and activity inspired by the growth of plant. The result reveals that combination of P. vittata and PAH-degrading bacteria can promote As accumulation and phenanthrene dissipation, and can be exploited as a promising strategy for As and PAH co-contamination remediation.

It is known that arsenic (As) promotes growth of As-hyperaccumulator Pteris vittata (PV), however, the associated mechanisms are unclear. Here we examined As-induced nutrient uptake in P. vittata and their potential role to enhance plant growth in sterile agar by excluding microbial effects. As-hyperaccumulator P. multifida (PM) and non-hyperaccumulator P. ensiformis (PE) belonging to the Pteris genus were used as comparisons. The results showed that, after 40 d of growth, As induced biomass increase in hyperaccumulators PV and PM by 5.2–9.4 fold whereas it caused 63% decline in PE. The data suggested that As played a beneficial role in promoting hyperaccumulator growth. In addition, hyperaccumulators PV and PM accumulated 7.5–13, 1.4–3.6, and 1.8–4.4 fold more As, Fe, and P than the non-hyperaccumulator PE. In addition, nutrient contents such as K and Zn were also increased while Ca, Mg, and Mn decreased or unaffected under As treatment. This study demonstrated that As promoted growth in hyperaccumulators and enhanced Fe, P, K, and Zn uptake. Different plant growth responses to As among hyperaccumulators PV and PM and non-hyperaccumulator PE may help to better understand why hyperaccumulators grow better under As-stress.

Although arsenic (As) hyperaccumulation is a constitutive property for Pteris vittata, there is intraspecific variation in As accumulation among metallicolous (from As-contaminated soils) and nonmetallicolous populations (from uncontaminated soils) and the related mechanisms is still not clear. Pot trials, hydroponic culture, and manual simulation were conducted to investigate the roles of arsenate reductase and root exudates in accumulating As in P. vittata, which were collected from two uncontaminated sites including Sun Yat-sen University campus, Guangdong Province (ZD), and a botanical garden in Guangxi Academy of Forestry Sciences, Nanning City, Guangxi Province (NN), and two As and Pb/Zn mining and/or smelting sites located in Shaoguan of Guangdong Province (SG) and Guiyang of Hunan Province (GY). The nonmetallicolous populations (ZD and NN) possessed more efficient uptake of arsenate and arsenite than the metallicolous populations (SG and GY). There were significant (p 67%). The NN population exuded 4.23 times more oxalate than the SG population. Root exudates from the NN population mobilized significantly (p

Phosphorus is an important macronutrient for plant growth and is acquired by plants mainly as phosphate (P). Phosphate transporters (Phts) are responsible for P and arsenate (AsV) uptake in plants including arsenic-hyperaccumulator Pteris vittata. P. vittata is efficient in AsV uptake and P utilization, but the molecular mechanism of its P uptake is largely unknown. In this study, a P. vittata Pht, PvPht1;2, was cloned and transformed into tobacco (Nicotiana tabacum). In hydroponic experiments, all transgenic lines displayed markedly higher P content and better growth than wild type, suggesting that PvPht1;2 mediated P uptake in plants. In addition, expressing PvPht1;2 also increased the shoot/root 32P ratio by 69–92% and enhanced xylem sap P by 46–62%, indicating that PvPht1;2 also mediated P translocation in plants. Unlike many Phts permeable to AsV, PvPht1;2 showed little ability to transport AsV. In soil experiments, PvPht1;2 also significantly increased shoot biomass without elevating As accumulation...

The ecological role of Arbuscular mycorrhizal fungi (AMF) has been widely reported to help Pteris vittata, an arsenic (As) hyperaccumulator, to effectively clean up As from contaminated environments. However, there is little information available on AMF community structures of in natural As-contaminated soils and their changing pattern along soil As concentration gradient, as well as their best predictor of environmental variables. In this study, soil samples from four sites with different As concentrations in Hunan Province of China were collected. Illumina MiSeq sequencing was used to investigate AMF community in the rhizosphere soils of P. vittata. Redundancy analysis (RDA) and mantel tests were used to determine the significance of environmental variables that may affect AMF community composition. A total of 95 OTUs were identified, with Glomeraceae, Gigasporaceae, Acaulosporaceae, and Scutellosporaceae shared by all sampling sites. Among Glomeraceae and Glomus were the dominant family and genus, respectively. The highest value of Shannon index was found when As concentration in soil was 147.92 mg/kg (site 2, p

Hyperaccumulation of arsenic (As) by brake fern Pteris vittata has been described as an important genetic trait that provides an option for development of a sustainable phytoremediation process for As mitigation. Accumulation of very high concentration of arsenic in above-ground tissues may be the result of arsenic vacuole compartmentalization, but the mechanism(s) of arsenic uptake and transport by underground tissues are largely unknown. In this study, we made an attempt towards understanding the molecular mechanism of As hyperaccumulation in this plant. A time-dependent As accumulation study indicates an exponential accumulation of As from 7 to 30 days of arsenic exposure in fronds, and day 3-7 in roots. Root transcriptome analysis identified 554,973 transcripts. Further, subsets of 824 transcripts were differentially expressed between treated and control samples. Many of the genes of critical As-stress response, transcription factors and metal transporters, biosynthesis of chelating compounds involved in uptake and accumulation mechanisms were identified. The genes that were highly expressed such as cysteine-rich RLK, and ABC transporter G family member 26 needs further studies along with arsenite transmembrane transporter. The analysis of generated transcriptome dataset has provided valuable information and platform for further functional studies.

This study investigates the V-resistant endophytic bacteria isolated from V-accumulator Pteris vittata grown on stone coal smelting district. Among all the ten isolates, the strain PRE01 identified as Serratia marcescens ss marcescens by Biolog GEN III MicroPlate™ was screened out by ranking first in terms of heavy metal resistance and plant growth promoting traits. The S. marcescens PRE01 had strong V, Cr and Cd resistance especially for V up to 1500mg/L. In addition, it exhibited ACC deaminase activity, siderophore production and high indoleacetic acid production (60.14mg/L) and solubilizing P potential (336.41mg/L). For heavy metal detoxification tests, PRE01 could specifically assimilate 97.6%, 21.7% and 6.6% of Cd(II), Cr(VI) and V(V) within 72h incubation. Despite the poor absorption of the two anions, most V(V) and Cr(VI) were detoxified and reduced to lower valence states by the strain. Furthermore, the isolate had the potential to facilitate the metals uptake of their hosts by changing heavy metal speciation. Our research may open up further scope of utilizing the endophyte for enhancing phytoextraction of vanadium industry contaminated soils.

Synchrotron μ-XRF and autoradiography complementally revealed the different behavior of arsenic and phosphorus in Pteris vittata L. at a high spatial resolution in its living state. We found that P...

Phytoextraction is a promising technology that uses hyperaccumulating plants to remove arsenic (As) and heavy metals (HMs) from soil. A field experiment has been conducted to evaluate impacts of water-soluble chitosan (WC) upon the growth and phytoextraction of As, Cd and Pb by the hyperaccumulator Pteris vittata L. and the economic plant castor bean ( Ricinus communis L.) in a co-planting system in polymetallic contamination of agricultural soil. The co-planting system was comprised of As-hyperaccumulator and Pb high-accumulating P. vittata and Cd high-accumulating R. communis . The results showed that yields of P. vittata were significantly increased by co-planting. The results revealed that the uptake of As and Pb by P. vittata was also significantly increased by co-planting. When the WC was applied to the co-planting system, the uptake of Cd and Pb by P. vittata and R. communis was significantly increased, but the uptake of As was not increased obviously. This study suggested that the combination of co-planting system with WC is a more promising approach than single hyperaccumulator. This approach not only enhanced the removal rates of soil As and HMs, but also simultaneously offered agricultural practices with no edible products in the As and HMs contaminated farmland soils.

The effects of arsenate-reducing bacterial inoculants (C13, F2, F2-As and compound microbial inoculant) on the remediation of arsenic (As) contaminated soil by Pteris vittata L. were studied in field experiments. The results showed that the application of F2, F2-As and the compound microbial inoculant significantly promoted plant growth, increased the As accumulation of P. vittata, and improved soil As removal efficiency. When compared with the uninoculated treatment, the frond biomass and As accumulation of P. vittata increased by 14.89% –50.98% and26.83%–54.26%, respectively, and the As removal rate increased by 0.55%–3.82%. The combination of the F2-As inoculant and P. vittata showed the highest remediation efficiency with the As removal rate reaching 6.66% during the 3-month experimental period. Application of arsenate-reducing bacterial inoculants increased the dissolved organic carbon content and available As content in rhizosphere soil of P. vittata by 15.67%–20.39% and 22.49%–44.09%, respectively, indicating that arsenate-reducing bacterial inoculants could modify As bioavailability and therefore might be beneficial for plant As accumulation. The results reveal that arsenate-reducing bacterial inoculants can improve the remediation efficiency of P. vittata, and can be exploited as a promising strategy for As contamination remediation.

Intercropping of Pteris vittata, an arsenic (As) hyperaccumulator, with crops is a method to realize the “production while remediation” of contaminated farmlands. However, the soil As remediation effects and the related mechanisms of P. vittata intercropping with different crops are rarely reported. In this study, by use of soil microplot experiment and root zone separation technique, the intercropping modes of P. vittata with maize (Zea mays L.), ramie (Boehmeria nivea (L.) Gaudich.) and castor (Ricinus communis L.) were designed to investigate the As and nutrient uptake and accumulation, antioxidant enzyme response, soil As fractionation, and the remediation effects of As contaminated soil by P. vittata-crop intercropping. The results showed that the intercropping increased As content of P. vittata by 3.1–25.3%, decreased As content of maize grains and leaves of ramie and castor by 70.9%–95.6%, 29.2%–32.0% and 18.8%–32.0%, respectively, indicating higher remediation efficiency by P. vittata-crop intercropping. The intercropping increased the total nutrient contents (NPK) of the three crops by 2.0%–91.1%, promoted plant biomass by 3.7%–111.0%, increased the transpiration rate by 4.9%–68.9%, and decreased the malondialdehyde (MDA) content by 7.0%–31.8%. Analysis also showed that the intercropping enhanced soil pH value and available As content in P. vittata rhizosphere. The proportion of iron-bound As was enhanced in P. vittata rhizosphere soil but decreased in three crops rhizosphere soil. The analysis of soil microbial diversity showed that the intercropping decreased the abundance of chloroflexi, increased the abundance of proteobacteria and actinobacteria. In summary, the P. vittata-crop intercropping had a positive significance for improving As remediation effect of P. vittata and reducing the As content in crops. Those modes could be applied in the practice of heavy metal contamination remediation along with crop production in farmland.