Highest Translocation Factor Research Articles

Urban weedy plantains (Plantago spp.) do not hyperaccumulate heavy metals nor shelter their soil microarthropod communities from these metals

Heavy metal hyperaccumulation by plants is a powerful tool in phytoremediation, where plants store heavy metals in large amounts in their aboveground tissue. Plant species in the Plantago genus exhibit this phenomenon, and their commonness in metropolitan centers around the world make them strong candidates for use in cities. Additionally, alteration of soil conditions by these plants can have cascading consequences on their soil microarthropod communities, which are strong bioindicators of soil health. To this end, we investigated the hyperaccumulation ability of two plantain species, Plantago lanceolata (non-native to North America) and Plantago rugelii (native to North America), and their soil microarthropod communities from field-collected specimens in Baltimore, MD, USA, which has an extensively documented legacy of heavy metal contamination. Notably, this is the first study to assess the influence of plant hyperaccumulation on soil microarthropod abundance and diversity using soil health bioindication metrics. First, we found that all sites sampled in Baltimore, MD exceed US governmental soil limits for As and Fe. Second, neither Plantago spp. hyperaccumulates any heavy metal in standard heavy metal screenings, though both species show signs of sequestration of some metals in their roots (i.e., phytoexclusion). Additionally, while native P. rugelii did not hyperaccumulate metals in this study, the relatively high translocation factor (TF or root: shoot) suggests it may have the capacity for it. We also found that soil microarthropod abundance was significantly greater in P. lanceolata rhizospheres (p<0.05), but bioindication of soil health (acari: collembola) was dependent on a combination of plant species identity and contamination level. Lastly, we found that soil microarthropod diversity was significantly affected by Al and As concentration.

Natural restoration of arsenic-contaminated environment with Quercus robur L. and Tilia cordata Mill.: 5-Year longitudinal study of dendroremediation dynamics

Investigating natural processes in arsenic (As) polluted areas and plants that have naturally chosen to grow there pose practical restoration recommendations. This study aimed to assess long-term changes in natural As dendroremediation dynamics for Quercus robur L. and Tilia cordata Mill., tree species capable of growing in areas polluted by mining activities. We examined total As and its forms, as well as B, Ca, K, Mg, Na and P, in soil and trees over 5 years. We also characterized pH and EC of soil, examined proline content in tree organs, and calculated Bioconcentration Factor (BCF) and Translocation Factor (TF) for As.Initial As concentrations in soil were 37.0 mg kg⁻1 under Q. robur and 34.7 mg kg⁻1 under T. cordata, significantly decreasing after 5 years to 10.5 mg kg⁻1 and 9.51 mg kg⁻1, respectively. This corresponds to pollution reduction of up to 71.8%. A notable decrease in As(III) and dimethylarsinic acid, along with increase in other organic As forms in soil, was observed. Additionally, concentrations of essential elements in soil, as well as its pH and EC, decreased over time.Both tree species accumulated substantial amounts of As in their organs, but the dynamics of this process were species-specific. During first 4 years, T. cordata accumulated more As and exhibited higher BCF, but in the 5th year, it was clearly surpassed by Q. robur. The highest TF was calculated for Q. robur in year 3, and for T. cordata in years 2 and 3. Generally, limited aboveground movement of As was indicated: BCF >1 were calculated for years 2 and 3, while TF were consistently <1. Proline content increased significantly in all organs, correlating with As, especially in Q. robur. In contrast, Q. robur leaves mapping revealed stable macroelement distributions, but clear variations were observed for T. cordata., which may suggest specific reaction to stress.These findings suggest that both species can effectively restore As-polluted areas, though with different dynamics. The selection of species for dendrorestoration should be based on whether the goal is faster remediation with lesser overall reduction (e.g. T. cordata) or slower remediation with ultimately greater pollution reduction (e.g. Q. robur).

Assessment of growth, metal uptake efficiency and yield traits of castor bean genotypes for phytoremediation of lead contaminated soils of Chakera-Faisalabad having history of long term irrigation with waste water

The agricultural soil of Chakera village, Faisalabad, Pakistan is under significant threat due to irrigation with wastewater containing Pb. Castor bean (Ricinus communis L.), a non-edible oil seed crop showed considerable capacity for phytoremediation of heavy metals. Restoration of Pb contaminated soil of Chakera using castor bean until physiological maturity could be an effective approach for mitigating hazardous impacts of Pb contamination in the soil. Hence, the present study aimed to evaluate the growth, biochemical traits, phytoremediation potential, and yield attributes of two castor bean genotypes (NIAB-2020 and DS-30) under the conditions of two different soil-filled pots; uncontaminated soil of NIAB (0 mg Pb kg−1) and contaminated soil of Chakera (250 mg Pb kg−1). Results have shown that plant agronomic, biochemical and seed compositional analysis have revealed a faint drop on Chakera soil. Metal accumulation response resulted in highest shoot Pb uptake in DS-30 compared to NIAB-2020. Conversely, maximum Pb uptake in roots of NIAB-2020 (4470 µg plant−1) was recorded when compared with DS-30 (3576 µg plant−1). Highest translocation factor (TF) was calculated for DS-30, whereas, for the metal tolerance index (MTI), both genotypes exhibited non-significant difference. Interestingly, concentration of Pb in seeds remained undetected for both genotypes. The study indicates that NIAB-2020 exhibited slightly higher tolerance than DS-30, potentially leading to economic gains through widespread use of castor oil across industries, positioning castor bean as a promising candidate for rehabilitation of contaminated soils. Nevertheless, additional in-situ investigations are necessary to validate the findings of current pot study.

Morphological Enrichment and Environmental Factors Correlation of Heavy Metals in Dominant Plants in Typical Manganese Ore Areas in Guizhou, China.

Bioavailable heavy metal and their efficient phytoremediation in mining areas have major implications for environmental and human health. In this study, we investigated 12 dominant plants in a typical Mn ore area of Zunyi, Guizhou Province, China, to determine the heavy metal contents, morphologies, and environmental factors affecting Mn, Cd, Pb, Cu, Zn, and Cr in the plant parts and rhizosphere soil. The bioavailabilities and degrees of metals were evaluated using the ratios of the secondary to primary phase distributions and potential ecological risk indices. Principal component analysis, cluster analysis, positive matrix factorisation modelling, and redundancy analysis were used to trace the origins and correlations among the metals. The results indicate that the bioavailabilities were the highest for Mn and Cd in the study area, and all of the target heavy metals had bioavailabilities above the moderate ecological harm level. Statistical modelling indicates that there are four main pollution sources: mining, smelting, processing operations, and atmospheric deposition. The dominant plants had high heavy metal enrichments, bioconcentration factors, and translocation factors for Mn, Cu, Cr, Cd, and Zn. The redundancy analysis indicates that soil total N, total P, and pH affect metal absorption and distributions in Compositae and non-Compositae plants in low-N, low-P, and slightly alkaline mining environments. This study provides a feasible basis for the screening of heavy metal enrichment plants and the improvement of remediation technology in manganese ore area under the extreme environment of poor nutrition.

How tree species have modified the potentially toxic elements distributed in the developed soil–plant system in a post-fire site in highly industrialized region

The biogeochemical cycles of trace elements are changed by fire as a result of the mineralization of organic matter. Monitoring the accumulation of trace elements in both the environment and the tree biomass during the post-fire (PF) forest ecosystem regeneration process is important for tree species selection for reforestation in ecosystems under anthropogenic pressure. We analyzed the soil concentrations of different groups of potentially toxic elements (PTEs), including beneficial (Al), toxic (Cd, Cr, Pb), and microelements (Cu, Mn, Ni, Zn), and their bioaccumulation in the tree species (Pinus sylvestris, Betula pendula, Alnus glutinosa) biomass introduced after a fire in a forest weakened by long-term emissions of industrial pollutants. The results indicated no direct threat from the PTEs tested at the PF site. The tree species introduced 30 years ago may have modified the biogeochemical cycles of the PTEs through different strategies of bioaccumulation in the belowground and aboveground biomass. Alder had relatively high Al concentrations in the roots and a low translocation factor (TF). Pine and birch had lower Al concentrations in the roots and higher TFs. Foliage concentrations and the TF of Cd increased from alder to pine to birch. However, the highest concentration and bioaccumulation factor of Cd was found in the alder roots. The concentrations of Cr in the foliage and the Cr TFs in the studied species increased from pine to birch to alder. Higher concentrations of Cu and Ni were found in the foliage of birch and alder than of pine. Among the species, birch also had the highest Pb and Zn concentrations in the roots and foliage. We found that different tree species had different patterns of PTE phytostabilization and ways they incorporated these elements into the biological cycle, and these patterns were not dependent on fire disturbance. This suggests that similar patterns might also occur in more polluted soils. Therefore, species-dependent bioaccumulation patterns could also be used to design phytostabilization and remediation treatments for polluted sites under industrial pressure.

Phytoremediation Potentiality of Bottle Gourd Plant (Lagenaria siceraria)

A pot experiment of bottle gourd plant with Pb, Zn, NPK and Vermicompost (VC) was carried out at the Department of Soil, Water and Environment, University of Dhaka. The aim of the study was to introduce a phytoremedial technique. The bottle gourd (Lagenaria siceraria) plant was used in the trial for evaluating its potentiality to accumulate Pb and Zn from soil and translocate these elements to different parts of the plant. Twelve treatments (T) were utilized in the experiment including control (T1). The remaining treatment groups were composed of different ratios of VC and recommended dose of NPK- with and without lead and Zinc. Tolerance to metal stress by the bottle gourd plant was evident in terms of higher biomass and yield production with the Pb and Zn. The maximum total biomass (leaf + stem + root) of fresh (67.49 g) and dry yield (8.41g) was achieved with Pb addition to T11. Bioconcentration factor (BCF) and Translocation Factor (TF) greater than one (BCF&gt;1 and TF&gt;1) were considered indicators of heavy metal accumulators and translocators, respectively. Among the Pb treatments, highest BCF achieved in leaf (1.67) with T12, in stem (1.82) with T8, in root (4.67) with T11 and maximum TF (2.87) found with T11. The Zn treatments exerted the highest BCF value in leaf (1.80), and in stem (1.64) with T10, in root (2.70) with T12, lowest value of BCF and TF were displayed in control (T1). Research exposed that bottle gourd plants had transferred both the heavy metals from soil significantly. The highest Pb accumulation in leaf was found to be 0.0023% (dry weight) in T10 and the lowest (0%) in T1. The highest translocation factor was found in T5 for Pb and in T11 for Zn. Moreover, bioconcentration factor (Pb) in shoots exhibited a significant, strong, and negative correlation (r = -0.804, p = 0.002) with the soil organic carbon content. There was also a strong, significantly negative correlation between total Pb content in soil and BCF (leaf) (r = -0.717, p = 0.009), as well as BCF (stem) (r = -0.692, p = 0.013). Similar relationship was found in case of Zn. The study revealed that bottle gourd plants possess phytoremedial potentiality which will be beneficial for the pollution context of Bangladesh. Further investigation is needed for greater research interest. Biodivers. Conserv. Bioresour. Manag. 2024, 10(1): 59-74

Dendroremediation of soil contaminated by mining sludge: A three-year study on the potential of Tilia cordata and Quercus robur in remediation of multi-element pollution

The vast amounts of mining and metallurgical wastes containing unimaginable quantities of toxic metal(loid)s require searching for managed ways. The study aimed to long-term assess the growth, elements accumulation (As, Cd, Hg, In, Mn, Mo, Pb, Sb, Sn, Ti, Tl, Zn) and proline content in 2-year-old Tilia cordata Mill. and Quercus robur L. seedlings growing under 1 and 3% extremely polluted mining sludge (MS) after 1, 2 and 3 years.Both species were able to grow efficiently without significant differences resulting from the impact of MS. The overall rise was higher for T. cordata than for Q. robur. The accumulation ability for As, Hg, In, Mn, Mo, Pb, Ti, and Zn in the whole plant was significantly higher for T. cordata, while Cd, Sb, Sn and Tl did not differ considerably between species. The highest content was found for As, Mn and Zn (68.7, 158, and 157 mg per plant, respectively) for T. cordata after 3 years of growth. The calculated Bioconcentration Factors were the highest for Cu (1.23), In (6.86), and Zn (38.4) for Q. robur, as well as for As (1.55), Hg (3.24), Mn (32.8), Mo (1.64) and Ti (18.0) for T. cordata after 3 years. The highest Translocation Factors were observed for In (1.35) and Sn (1.25) after 3 years, as well as for Mn (2.72, 3.38, and 3.03 after 1, 2, and 3 years) for Q. robur seedlings. The proline content was higher for Q. robur, regardless of which organ was examined, and the differences increased with the time of the experiment and the amount of MS addition (possibly more sensitive to stress).Young T. cordata seedlings show much greater potential than Q. robur. This is the first time that a demonstration of the high potential of long-living trees in multi-element MS remediation has been described.

Sustainable use of composted sewage sludge: Metal(loid) leaching behaviour and material suitability for application on degraded soils

Composted sewage sludge was investigated as a promising material for the reclamation or remediation of degraded sites. Using sewage sludge as soil amendment provides environmental benefits and risks while supporting circularity and waste minimisation. This study aims to comprehensively assess the suitability of locally available low-cost sludge treatment for sustainable and environmentally safe topsoil disposal in a brownfield area affected by coal mining. A nine-month composting was conducted before field application to the soil environment. The objectives were to assess: (i) composting time-dependent and pH-dependent metal(loid) leachability from composted sludges, (ii) the effect of sludges on metal(loid) leachability from soil over the first six months, and (iii) metal(loid) plant uptake during the first vegetation season as well as the bioaccumulation and translocation factors. The set of standardised leaching experiments confirmed the positive effect of compost maturity, i.e. despite some fluctuations over time, metal(loid) availability from the final composts was very low. Some metals showed unusual pH-dependent behaviour with the highest leachability at pH 8 due to excessive release of dissolved organic matter from the not-yet-stabilised matrix. Ecotoxicity testing confirmed the safety of the final composts for further soil application. The sludge-amended plots displayed similar metal(loid) leaching and pH evolution in time compared to the control biomass-amended plot. However, plant species (Artemisia vulgaris L.) that formed the natural vegetation cover of the experimental plots showed cumulative metal(loid) uptake. Cadmium and zinc were identified as the critical metals possibly related to the applied sludges, yielding high bioaccumulation and translocation factors. Yet, the quality of the compost feedstock, heterogeneity, and background values of the brownfield site need to be considered. Nevertheless, soil respiration indicated no adverse effects on soil health six months after sludge application. Overall, the composted material demonstrated potential suitability for remediation application in the studied area.

Bioaccumulation Characteristics of Typical Perfluoroalkyl Compounds in Alfalfa Under Salt Stress.

Medicago sativa, commonly known as alfalfa, is widely distributed worldwide, known for its strong stress resistance and well-developed root system, making it an important plant in ecological restoration research. To investigate the absorption and transport characteristics of alfalfa for typical perfluoroalkyl substances (PFAS) under salt stress, a 30-day indoor greenhouse experiment was conducted. The results showed that alfalfa exhibited varying degrees of absorption and transport for the selected PFAS. The highest BCF (Bioconcentration Factor) for shoot tissue reached 725.4 (for PFBA), and the highest TF (Translocation Factor) reached 53.8 (for PFPeA). Different PFAS compounds exhibited distinct bioaccumulation behaviors, with short-chain PFAS more readily entering the plant's root system and being transported upwards, while long-chain PFAS tended to adsorb to the surface of the root system. Furthermore, salt stress did not significantly affect the uptake of PFAS by alfalfa. This suggests that alfalfa is salt-tolerant and holds great potential for ecological restoration in short-chain PFAS-contaminated sites.

Evaluation of phytoremediation efficiency of shooting range soil using the bioaccumulation potential and sensitivity of different plant species

Shooting range soil is one of the most heavily contaminated sites in the world with heavy metals from shooting activities. The aim of the study was to evaluate remediation efficiency of contaminated shooting range soil using three plant species – Festuca arundinacea Schreb., Trifolium pratense L., and Medicago sativa L. assessing the impact of contamination on the development of plant species and the capacity of plants to accumulate potentially toxic elements from polluted soil. The field study was conducted in a Lithuanian civilian shooting range operating 65 years where lead (Pb) concentration in the shooting range soil was extremely high – 17,890 mg kg−1 and the elevated levels of antimony (Sb) was found in soil of berm. F. arundinacea had the highest biomass. The shoot height of all species grown in the contaminated shooting range soil was significantly lower than that of those grown in the uncontaminated soil. The shoot height of M. sativa and T. pratense was 30% lower compared to the control group, while the height reduction of F. arundinacea was only 10%. The same trend of the effect of contaminated soil on root length was observed - the roots were statistically significantly shorter than the control, while the mean root length of F. arundinacea did not differ from the control plants. The content of photosynthetic pigments in all three species tested was also significantly lower as that of the control plants due to contaminated shooting range soil. Shoots of T. pratense plants grown in the shooting range soil accumulated 10 times higher concentrations of Pb and 3 times higher concentrations of Sb in M. sativa compared to the control. Among all studied plants, F. arundinacea was the plant capable of accumulating significantly higher amounts of Pb, nickel (Ni) and Sb in roots than in shoots. The roots of all treated plants accumulated significantly higher concentrations of Pb compared to the control. The highest concentrations of Pb were determined in the shoots of F. arundinacea and T. pratense. Only the roots of M. sativa and F. arundinacea, accumulated higher concentrations of Ni and Sb, compared to controls. The significantly higher bioconcentration factor of Pb (BCFPb) was determined in F. arundinacea but it still was lower than 1.0. The Pb accumulation capacity of the different plant species was in the following order: F. arundinacea > T. pratense > M. sativa showing phytostabilization potential of plants. T. pratense had the highest translocation factor (TF) values, being able to translocate a high proportion of Pb and Sb from roots to shoots, while F. arundinacea had the lowest efficiency.

Dark septate endophyte inoculation improved Pb phytoremediation of Jatropha curcas and Reutealis trisperma on gold mine tailings

This study investigated the symbiotic potential of Jatropha curcas and Reutealis trisperma with two isolates of dark septate endophyte (DSE) fungi (Cladosporium sp. and Rhyzopycnis vagum) grown on gold mine tailings media based on their ability to remediate Pb and their morphological, physiological, and anatomical changes. The targeted plants were grown for 12 weeks on different media contained mixed soil and compost, gold mine tailings, and tailing with additional charcoal. The result showed that DSE inoculation increased the height of J. curcas up to 24.1% in contaminated soil compared to control treatment without DSE. All DSE fungi were able to colonize both root plant even under gold mine tailing treatment. DSE inoculation increased chlorophyll content of both plants ranging from 11% to 33% compared to the plants without DSE. Jatropha curcas inoculated with DSE had the potential to be used as phytoremediation plant with a phytoextraction mechanism indicated by higher translocation factor (TF) value. Meanwhile, the R. trisperma was able to be used for phytoremediation categorized as phytostabilization due to lower TF values. The results of this study highlighted the possible role of the DSE symbiotic with J. curcas and R. trisperma to improve the efficiency of phytoremediation in contaminated lands.

Combination of melatonin and plant growth promoting rhizobacteria improved the growth of Spinacia oleracea L. under the arsenic and cadmium stresses

Arsenic and cadmium are among highly toxic elements that causes detrimental effects to the plants, animals as well as human beings. Melatonin is a natural molecule that works as a strong antioxidant by forming antioxidant cascade reaction by scavenging free radicals of reactive oxygen species (ROS). In the same way, plant growth promoting rhizobacteria (PGPR) colonize plant roots and enhance plant growth by number of mechanisms. The objective of the current research was to study the impact of melatonin and Bacillus licheniformis in combination on Spinacia oleracea L. in the presence of arsenic (As) and cadmium (Cd) stress. Spinacia oleracea L. seeds were germinated in pots consisting of control and three different doses of arsenic and cadmium irrigated with combination of melatonin and Bacillus licheniformis. The results of the study showed that the combination of melatonin and Bacillus licheniformis has the potential to alleviate the toxic effects of As and Cd. Plant morphological and physiological parameters like plant height, root length, fresh weight, dry weight, chlorophyll content were enhanced because of combine application of melatonin and Bacillus licheniformis. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity increased because of combine application of melatonin and Bacillus licheniformis while malondialdehyde (MDA) content is decreased. In response to different stress conditions, expression of genes encoding the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) is increased in different As and Cd treatments. Results show that highest translocation factor (TF) 0.44 was observed at 125 mg/kg Cd and highest bioconcentration factor (BCF) 0.46 at 75 mg/kg Cd. All three treatments have TF and BCF less than one thus making Spinacia oleracea L. useful for uptake by human beings. Additionally, it was found the melatonin content in Spinacia oleracea L. was increased under As and Cd stress and exogenous melatonin application.

High phytoremediation and translocation potential of an invasive weed species (Amaranthus retroflexus) in Europe in metal-contaminated areas

We demonstrated the metal accumulation potential of Amaranthus retorflexus, a European weed species, both in moderately and strongly metal-contaminated sites. Metal accumulation in roots, stems, and leaves were studied. We also calculated the bioaccumulation factor (BAF), and translocation factor (TF) values to quantify the metal accumulation, and translocation between plant organs. Our findings indicated that metal accumulation correlated with metal concentration; that is plant organs accumulated higher concentration of metals in the contaminated area than in the control one. We found that the concentrations of Ba, Mn, Sr and Zn were the highest in leaves, and Al, Cr, Cu, Fe and Pb in roots. High BAF value was found for Sr in all studied areas, indicating this metal’s high accumulation potential of Amaranthus retorflexus. High TF values were found for Al, Ba, Cu, Fe, Mn, Sr and Zn; these metals were successfully transported to aboveground plant organs. We demonstrated that A. retroflexus, a fast-growing, rapidly spreading weed in Europe, was especially useful for heavy metal phytoremediation and phytoextraction.

Investigation of water-soil-plant relationships based on hazardous and macro-micro element concentrations on Orontes River, Türkiye

Arundo donax and Phragmites australis were examined in 4 different periods (June and October for 2 years), heavy metal and mineral element accumulations in plants were evaluated, and water-soil-plant relationships were revealed. Element distributions, bioaccumulation factors (BAF) and translocation factors (TF) in different parts of the investigated plant species were also determined. BAFs of elements calculated by using the concentration values in underground parts and sediment samples were between 1.02 and 4.96. While the highest TF was determined as 8.07 for Zn between washed leaf and stem in A. donax, the lowest TF was determined as 0.05 for Fe between stem and underground part. Corresponding highest and lowest TFs for P. australis were 11.80 for Cu between washed leaf and stem, and 0.02 for Fe between stem and underground part, respectively. The results were supported by MANOVA statistical analyzes. Additionally, the macro-micro elements and heavy metal accumulation levels in the parts of the Orontes River ecosystem were significantly higher in the fall periods compared to the spring periods. Our research revealed that the versatile accumulation properties and high accumulation ability of A. donax for Cd, Cr, and Ni and of P. australis for Cd, Co, Cu, Ni, Pb, and Zn.

Trifolium pratense and the Heavy Metal Content in Various Urban Areas

Effective biomonitoring strategies are essential for identifying and assessing the sources and levels of contamination of heavy metal pollutants in urban areas, given their negative impacts on human health and the environment. This study aimed to assess the potential of common weed, Trifolium pratense as a bioindicator of heavy metal contamination in various land uses in urban areas, with a focus on Cd, Cu, Cr, Ni, and Pb. The results have shown that Cr and Ni had high bioconcentration factor (BCF) values in most sites, in comparison with Cu, Cd and Pb. Contamination factor (CF) values varied across all sites. The industrial area and old town sites had the highest translocation factor (TF) values for Cr and Ni, indicating greater transport of these metals from roots to aerial parts of plants. Differences between heavy metals (HMs) according to land use were observed; especially, Pb and Cu were more concentrated in soils than other heavy metals in industrial areas. Overall, these findings suggest that Trifolium pratense is a promising bioindicator for heavy metal contamination in various land uses in urban areas, making it a potentially valuable tool for monitoring heavy metal pollution in cities of the northern hemisphere.

Response to Hypersalinity of Four Halophytes Growing in Hydroponic Floating Systems: Prospects in the Phytomanagement of High Saline Wastewaters and Extreme Environments.

Hypersaline environments occur naturally worldwide in arid and semiarid regions or in artificial areas where the discharge of highly saline wastewaters, such as produced water (PW) from oil and gas industrial setups, has concentrated salt (NaCl). Halophytes can tolerate high NaCl concentrations by adopting ion extrusion and inclusion mechanisms at cell, tissue, and organ levels; however, there is still much that is not clear in the response of these plants to salinity and completely unknown issues in hypersaline conditions. Mechanisms of tolerance to saline and hypersaline conditions of four different halophytes (Suaeda fruticosa (L.) Forssk, Halocnemum strobilaceum (Pall.) M. Bieb., Juncus maritimus Lam. and Phragmites australis (Cav.) Trin. ex Steudel) were assessed by analysing growth, chlorophyll fluorescence and photosynthetic pigment parameters, nutrients, and sodium (Na) uptake and distribution in different organs. Plants were exposed to high saline (257 mM or 15 g L-1 NaCl) and extremely high or hypersaline (514, 856, and 1712 mM or 30, 50, and 100 g L-1 NaCl) salt concentrations in a hydroponic floating culture system for 28 days. The two dicotyledonous S. fruticosa and H. strobilaceum resulted in greater tolerance to hypersaline concentrations than the two monocotyledonous species J. maritimus and P. australis. Plant biomass and major cation (K, Ca, and Mg) distributions among above- and below-ground organs evidenced the osmoprotectant roles of K in the leaves of S. fruticosa, and of Ca and Mg in the leaves and stem of H. strobilaceum. In J. maritimus and P. australis the rhizome modulated the reduced uptake and translocation of nutrients and Na to shoot with increasing salinity levels. S. fruticosa and H. strobilaceum absorbed and accumulated elevated Na amounts in the aerial parts at all the NaCl doses tested, with high bioaccumulation (from 0.5 to 8.3) and translocation (1.7-16.2) factors. In the two monocotyledons, Na increased in the root and rhizome with the increasing concentration of external NaCl, dramatically reducing the growth in J. maritimus at both 50 and 100 g L-1 NaCl and compromising the survival of P. australis at 30 g L-1 NaCl and over after two weeks of treatment.

Effects of Soil pH on the Growth and Cadmium Accumulation in Polygonum hydropiper (L.) in Low and Moderately Cadmium-Contaminated Paddy Soil

Wetland macrophytes have advantages when used in the remediation of cadmium (Cd)-contaminated paddy fields because they can adapt to overly wet soil environments; however, only a few studies have tested the efficiency of macrophytes in Cd phytoremediation. In this study, we investigated the effect of soil pH (pHs of 5, 6, and 7) on the accumulation and translocation of Cd by Polygonum hydropiper (L.) in low and moderately Cd-contaminated paddy soil (0.56 and 0.92 mg/kg, respectively). Our results indicated that Cd accumulation in stems and roots, as well as subcellular distribution in P. hydropiper, was affected by soil pH, with significant interactions between the soil pH and Cd level. At low soil Cd levels, stem and root Cd contents were higher at a soil pH value of 6. In addition, with higher soil pH values, the proportion of Cd distributed in the cell wall increased, whereas that distributed in the organelles decreased. The Cd content in the roots and stems of P. hydropiper significantly decreased with the increase in soil pH in the moderate Cd-contaminated soil. In addition, with higher soil pH values, the proportion of Cd distributed in the cell wall decreased, whereas that distributed in the organelles increased. The translocation factor (TF) of P. hydropiper was higher than one in all treatments, indicating that it can effectively transport root-absorbed Cd to the aboveground shoots. Based on the relatively high bioconcentration factor and TF, P. hydropiper has the potential to remediate Cd-polluted paddy soil. Furthermore, the remediation efficiency of P. hydropiper can be enhanced by adjusting the pH as per the soil-Cd pollution.

Role of different organic and inorganic amendments in the biofortification of iodine in Coriandrum sativum crop

Iodine deficiency disorder (IDDs) is one of the most prevailing and common health issues in mountainous communities. An effective way to control the prevalence and emergence of IDDs in remote areas is to use iodized salt. However, recent studies indicated that iodized salt is mostly lost during the cooking process. The current study of iodine biofortification differed from the previous studies in two main aspects: it involved exogenous organic iodine (OI), and inorganic iodine such as potassium iodide (KI), added in the amended soils, which previous studies did not consider. Moreover, the translocation, transformation, and distribution of iodine from soil to plants are poorly understood in amended soil. Thus, identifying an effective management option to enhance iodine (I) bioavailability in nutrient-deficient soils is currently a significant challenge. Therefore, a greenhouse study was conducted to investigate the effects of organic and inorganic soil amendments on the uptake of different iodine sources in coriander crops. Results showed that applying an inorganic iodine source significantly enhanced the iodine edible part of the crop compared to the control (p &amp;lt; 0.05). The application of soil amendments relatively improved iodine uptake by the coriander crop compared to the control. The highest iodine was found in crop tissues grown in wood ash-amended soil supplemented with KI (291.97 μg kg−1). The KI uptake was significantly higher than the OI (p &amp;lt; 0.05). Compared to OI, a higher translocation factor (0.96) and distribution coefficient (3.51) were found for plants treated with KI. Thus, this study indicates that a suitable soil amendment can be a better option for iodine biofortification and that it can serve as an alternative to iodized salt in preventing IDDs.

Mercury accumulation potential of aquatic plant species in West Dongting Lake, China

West Dongting Lake is a protected wetland with the potential for high levels of mercury release via wastewater and deposition from industry and agriculture during the last decade. To find out the ability of various plant species to accumulate mercury pollutants from soil and water, nine sites were studied in the downstream direction of the flow of the Yuan and Li Rivers, which are tributaries of the Yellow River flowing into West Dongting Lake, where mercury levels arere high in soil and plant tissues. The total mercury (THg) concentration in wetland soil was 0.078–1.659 mg/kg, which varied along the gradient of water flow along the river. According to canonical correspondence analysis and correlation analysis, there was a positive correlation between the soil THg concentration and the soil moisture in West Dongting Lake. There is high heterogeneity in the spatial distribution of soil THg concentration in West Dongting Lake, which may be related to the spatial heterogeneity of the soil moisture. Some plant species had higher THg concentrations in aboveground tissues (translocation factor >1), but none of these plant species fit the criteria as hyperaccumulators of mercury. And some species of the same ecological type (e.g., emergent, submergent, floating-leaved) exhibited very different strategies for mercury uptake. The concentrations of mercury in these species were lower than in other studies but these had relatively higher translocation factors. To phytoremediate soil mercury in West Dongting Lake, the regular harvest of plants could help remove mercury from soil and plant tissue.

Improving the uptake of PAHs by the ornamental plant Sedum spectabile using nano-SiO2 and nano-CeO2

Polycyclic aromatic hydrocarbons (PAHs) pollution is a global ecological soil problem. Screening and establishing an efficient phytoremediation system would be beneficial for alleviating this problem. The ornamental plant Sedum spectabile was selected as the remediation plant to study the removal efficiencies of PAHs after adding different concentrations of nano-SiO2, nano-CeO2, and traditional Na-montmorillonite (Na-MMT). The results demonstrated that shoot biomass was increased and photosynthesis was enhanced by the nanomaterial amendments. The uptake of 16 PAHs by S. spectabile was remarkably increased. Moreover, the two highest shoot concentrations were 7.61 (Phe) and 12.03 (Flo) times that of the control, and the two highest translocation factors were 31 (BbF) and 28 (BaP) times that of the control. Furthermore, 16S rRNA gene sequencing showed that the addition of nano-SiO2 increased the abundance of Acidobacteria, and the genera related to PAH degradation was higher under nanomaterial treatments. The very high Si concentration in the shoots of S. spectabile had a significant linear correlation with the concentration of PAHs. In conclusion, the S. spectabile remediation system assisted by two nanomaterials was effective for the removal of PAHs from soil, and the transfer of PAHs to easily harvested aboveground plant parts was especially worthy of attention.