Metal Accumulation Capacity Research Articles

Tilapia as a model fish for biomonitoring of metal pollution in dams associated with mining watersheds: contrasting diagnosis from different tissues and health risk assessment.

Tilapia is a model fish species used as a pollution biomonitor due to its tolerance and availability in many contaminated sites. Blue tilapia Oreochromis aureus specimens (n = 320) were collected in eleven dams influenced by mining in the SE Gulf of California region (dams 1, 2 and, 3 comprise 55 mining sites; dam 4 comprises 8; dams 6, 8, 10, and 11, ≤ 6; and dams 5, 7, and 9 include 19, 20, and 16 mining sites, respectively). Cadmium, Cu, Pb, and Zn concentrations were analyzed in the muscle, liver, gills, and guts to identify metal pollution and evaluate risks and seasonal changes. The distinct tissues exhibited different metal accumulation capacities, therefore allowed develop a diagnosis comparative between the eleven dams. In general, metal concentrations were higher in dams 1, 2, 5, and 9, which are associated with more mining sites in their sub-basins. The four metals exhibited the highest levels in the tilapia liver in dams 1 and 2, which can be related to the present and past mining activity in the lower watershed (55 sites) and the geothermal activity in these dams. In general, Zn exhibited the highest level in the tilapia livers from dams 1, 2, 3, 4, 5, and 10 compared to the maximum mean (220µg/g) concentrations previously recorded. The non-carcinogenic risks indicated that the Pb risk was enhanced when the intake was ≥ 231.5gweek-1 of tilapia muscle, indicating a potential risk of adverse health effects for the entire population.

Macrophytes as Bioindicators of Heavy Metal Pollution in Belarusian Rivers

ABSTRACTMacrophytes are well‐known for accumulating a large number of various substances, including metals, and they may consequently serve as biogeochemical indicators of aquatic system pollution. In general, the sequence of analyzed metal accumulation in river macrophytes is as follows (mg/kg): Mn (141) > Cu (2.53) > V (0.89) > Cr (0.70) > Pb (0.68) > Ni (0.23). Submersed species are conspicuous for their increased metal accumulation capacity, with statistically significant differences compared to other ecological groups. Among the aquatic plant genera examined (Potamogéton, Ceratophýllum, Elodea, Núphar, Butomus, Glycéria, and Spargánium), an increased capacity to accumulate Mn, Cu, and Pb is observed in all submersed macrophytes, while Cr, V, and Ni are particularly accumulated by Ceratophýllum and Elodea. Potamogéton has the largest range of V, Cr, Mn, Ni, and Cu variations. The overall bioaccumulation capability evaluated by the metal accumulation index was ordered as follows: Núphar (6.94) > Potamogéton (5.53) > Butomus (3.48) > Glycéria (2.86) > Spargánium (2.62) > Elodea (2.33) > Ceratophýllum (1.98). Bio‐accumulation factors (BAFs) (macrophytes/sediment) vary depending on the metal and macrophyte ecological groups. For submersed macrophytes, the sequence of BAFs is Mn > Cu > Ni > Pb > Cr > V. In the submersed plants of watercourses taken at the anthropogenic impact sites, the accumulation of Ni, V, Mn, Pb, and Cu is statistically significantly higher compared to those in natural conditions. Compositional data analysis has revealed such biogeochemical signatures of the anthropogenic impact as the formation of the anthropogenic Cr–Ni association, which is associated with the identified multivariate anomalies, as well as an increase in Cu variability and a decrease in Mn.

Influence of biochar amendment on removal of heavy metal from soils using phytoremediation by Catharanthus roseus L. and Chrysopogon zizanioides L.

Advances in sustainable toxic heavy metal treatment technologies are crucial to meet our needs for safer land to develop an urban resilient future. The heavy metals bioaccumulate in the food chain due to their persistence in the soil, which poses a serious challenge to its removal and control. Utilisation of hyperaccumulators to reduce the mobility, accumulation and toxic impact of heavy metals is a promising and ecologically safe technique. Amendments such as biochar and chelates have been shown to enhance the phytoremediation efficiency. However, the potential soil improvement is influenced by the properties of the amendment, plant and metal heterogeneities. In this study, an organic sugarcane bagasse biochar amendment for the 60-day pot experiment using Catharanthus roseus L. (NT) and Chrysopogon zizanioides L. (VT) in a heavy metal-contaminated soil was applied. The influence of biochar on the phytoremediation of lead (Pb), zinc (Zn) and cadmium (Cd) from the soil was explored. The plant survival rate enhanced to 100% with biochar amendment, and the biomass increased from 5.83 to 15g in Zn-contaminated samples. Nutrients such as potassium concentration are directly correlated to the amendment rates, whereas phosphate decreases beyond the 2% biochar amendment rate in both plants. High heavy metal accumulation capacities with improved growth with biochar indicate the sustainability of the process. The translocation factor (TF) > 1 for Zn in NT represents the phytoextraction efficiencies whereas VT indicates high BCF values in the range of 0.5-3.53 for the amended Zn-contaminated soils. The findings indicate that the amendment rate of 2% improves nutrient cycling, plant biomass and heavy metal removal efficiencies. The insights from this study establish that the synergy between biochar amendment and the selected medicinal plants improved the phytoremediation efficiency.

Effects of heavy metals and high temperature on Atlantic Forest species: Analysis of their tolerance capacity

Changes in temperature and the deposition of potential pollutants in the soil, such as heavy metals, may damage plant communities, altering their physiological processes. High temperature may also cause a series of morpho-anatomical, physiological and biochemical changes in plants. However, tolerant plant species tend to restrict these harmful effects. The present study investigates the impact of atmospheric warming on the accumulation capacity of heavy metals (Zn, Ni, Cu) in the roots and leaves of a pioneer species (Croton floribundus) and a non-pioneer species (Esenbeckia leiocarpa) native to the Atlantic Forest of southeastern Brazil. The experimental design involved exposing the plants to two soil treatments: without excess metals (-M) and with excess metals (+M), along with varying thermoperiods of 26 °C day/19 °C night and 32 °C day/20 °C night in growth chambers. Over a 28-day period, we assessed weekly metal content, translocation, growth parameters, a non-enzymatic antioxidant (glutathione) and indicators of cell damage or oxidative stress (chlorophylls a and b, total chlorophyll (a+b), carotenoids, malondialdehyde and conjugated diene hydroperoxide contents). Both species exhibited increased metal accumulation under excess metals, employing distinct translocation strategies. C. floribundus showed high translocation rates of Ni to leaves and E. leiocarpa immobilized Ni in the roots. Atmospheric warming reduced Cu and Ni translocation from roots to leaves in both species. C. floribundus displayed lower physiological damage compared to E. leiocarpa, demonstrating robust growth. We concluded that the pioneer species possessed greater tolerance to oxidative stress induced by temperature and metal-related environmental factors than the non-pioneer species, confirming our hypothesis. In addition, our finding provides valuable insights for conservation and management of ecosystems affected by climatic and pollutant changes.

The effect of heavy metals (Cd, Cu, and Pb) on plant growth parameters and the phytoremediation capacity of corn

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Влияние тяжелых металлов (Cd, Cu и Pb) на параметры роста растений и фиторемедиационную способность кукурузы

Heavy metal contamination is currently a major global environmental issue. Heavy metals contaminate the soils where crops and vegetables grow. Maize (Zea mays L.) is widely employed for phytoremediation because of its high biomass output and metal accumulation capacity. Depending on the plant and soil properties, some metals can be dangerous in high amounts. During our in vitro experiment, different levels of Cd, Cu, and Pb were introduced to a growth medium to allow maize plants to develop under diverse conditions. The study examined numerous growth features under certain metal stress conditions, including seed germination, plant height, biomass, and chlorophyll content, as well as the toxicity symptoms and mechanisms of the most common heavy metals. The study revealed that, while the maize plant is a good heavy metal accumulator, high heavy metal concentrations had a negative impact on several growth indicators: at 250 ppm, Cd inhibited captive seed germination by 50% and wild seed germination by 42.9%; Pb suppressed captive seed germination by 57% and wild seed germination by 42.9%; and Cu inhibited germination in both seed types by 40%. Similarly, plant height decreased in the following order: Pb (36.2%), Cd (24.8%), and Cu (9.7%) for the captive seed plant, and Pb (46.7%), Cd (28%), and Cu (13%) for the wild seed plant. Keywords: MAIZE, STRESS, TOXICITY, HEAVY METAL, POLLUTION, PHYTOREMEDIATION, BIOACCUMULATION

Potential of Plant Based Metallophytes for Phytoremediation in Agriculture

Metallophytes are the unique group of plants that have evolved to thrive in metal rich environments and have drawn plenty of attention. Remediating heavy metal contaminated places with plants is an effective choice due to phytoremediation, an environmentally friendly method that uses plants to mitigate the pollution. Metallophytes are ideal options for phytoremediation applications due to their inherent traits such as hyper-accumulation, efficient metal absorption and tolerance mechanisms impacting both the plant and soil. These plants absorb and translocate heavy metals, detoxifying the soil while accumulating them in tissues. This reduces metal toxicity in soil and holds potential for resources recovery. The role of metallophytes in phytoremediation is analysed in this review with particular focus given to their ways of metal absorption, translocation and detoxification. Metallophytes have high metal tolerance and accumulation capacities due to their unique physiological and biochemical adaptations including enhanced metal sequestration in vacuoles, metal chelation by phytochelatins and activation of anti-oxidant defence systems. This review also highlights the significance of metallophytes in enhancing the soil health, reducing metal bioavailability, and promoting the ecological sustainability as well as their potential for restoring contaminated ecosystems. Utilizing the unique capabilities of metallophytes obtained from plants possesses enormous possibilities to minimise the negative effects of heavy metal pollution, protect ecosystems, and promote sustainable development for future generations. Eventually, it outlines future research approaches that aim to enhance metallophytes based phytoremediation strategies, widen their implementation and include them in holistic approaches for environmental restoration and sustainable land management.

Biomonitoring potentially toxic elements in atmospheric particulate matter of greater Dhaka region using leaves ofhigher plants.

In this study, four different plant species, namely Artocarpus heterophyllus, Mangifera indica, Psidium guajava, and Swietenia mahagoni, were selected from seven different locations to assess the feasibility of using them as a cost-effective alternative for biomonitoring air quality. Atmospheric coarse particulate matter (PM10), soil samples, and leaf samples were collected from residential, industrial, and traffic-congested sites located in the greater Dhaka region. The heavy metal concentrations (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the leaves of the different species, PM10, and soil samples were analyzed. The highest Pb (718ng/m3) and Zn (15,956ng/m3) concentrations were found in PM10 of Kodomtoli which is an industrial area. On the other hand, the highest Fe (6,152ng/m3) and Ni (61.1ng/m3) concentrations were recorded in the PM10 of Gabtoli, a heavy-traffic area. A significant positive correlation (r = 0.74; p < 0.01) between Pb content in plant leaves and PM fraction was found which indicated that atmospheric PM-bound Pb may contribute to the uptake of Pb by plant leaves. The analysis of the enrichmentfactor (EF)revealed that soils were contaminated with Cd, Ni, Pb, and Zn. The abaxial leaf surfaces of Psidium guajava growing at the polluted site exhibited up to a 40% decrease in stomatal pores compared to the control site. Saet's summary index (Zc) demonstrated that Mangifera indica had the highest bioaccumulation capacity. The metal accumulation index (MAI) was also evaluated to assess the overall metal accumulation capacity of the selectedplants. Of the four species, Swietenia mahagoni (3.05) exhibited the highest MAI value followed by Mangifera indica (2.97). Mangifera indica and Swietenia mahagoni were also found to accumulate high concentrations of Pb and Cr in their leaves and are deemed to be good candidates to biomonitor Pb and Cr contents in ambient air.

Investigation of Heavy Metal Concentrations and Accumulation Capacities of Naturally Growing Species in Old Garbage Area

In underdeveloped and/or developing countries, garbage is often randomly piled up in open areas. This method has been used to dispose of garbage/solid waste in Turkey for many years. Although pollution is not at the forefront in Bingöl province, the area located in the city center of the city has been used as a wild garbage storage area for approximately 18 years. Since the garbage in the area poses a danger to people and the environment, this area has become inactive with the establishment of a new solid waste disposal facility in the city. There are plants that have adapted to this area, which has been empty for about ten years. In this study, it was tried to determine in what proportions and organs the plant species distributed in the area accumulate heavy metals that may have come from garbage leachate. Plants identified in the field; Alyssum simplex, Cirsium libanoticum, Descurainia sophia, Fumaria asepala, Fumaria officinalis, Matricaria chamomilla, Papaver dubium, Scrophularia canina, Trifolium repens and Ziziphora capitata species. Fe, Cr, As, Cd and Pb concentrations (mg kg-1) of these species were measured in root, stem, leaf and flower organs and translocation factors (TF) were calculated for these species. In conclusion; Alyssum simplex, Cirsium libanoticum and Fumaria asepala for Fe, Cirsium libanoticum, Fumaria asepala, Fumaria officinalis and Matricaria chamomilla Cr and As, Cirsium libanoticum, Papaver dubium and Scrophularia canina for Cd and all other species except Alyssum simplex and Scrophularia canina for Pb translocation factors (TF) were found to be greater than 1 (TF&amp;gt;1). The accumulation potential of these species is thought to be promising so that they can be evaluated in phytoremediation.

Human health risk assessment of heavy metals accumulation in different genders and tissues of whiting fish (Merlangius merlangus euxinus Nordmann, 1840) from Rize, Turkey

The contamination of fish resulting from marine pollution is a major concern, as it poses potential adverse effects on human health. Therefore, heavy metal concentrations (Cr, Fe, Ni, Cu, Zn, and Pb) in different genders and tissues (muscle, liver, gonads and gills) of whiting fish collected from fish markets in Rize province were determined by Inductively–coupled plasma optic emission spectrometry (ICP–OES). The concentration ranges of heavy metals in all tissue samples, based on the overall average, were as follows (mg/kg wet weight): Cr: 0.081–0.25, Fe: 2.3–40, Ni: 0.070–0.095, Cu: 0.33–1.01, Zn: 3.0–20, and Pb: 0.015–0.043. The results indicated that the liver and gills exhibited a higher metal accumulation capacity compared to other tissues, whereas the muscle consistently displayed the lowest metal concentrations. The metal concentrations in the muscle were found to be below the maximum permissible levels set by international organizations for seafood. Additionally, calculated estimated daily intake (EDI), metal pollution index (MPI), target hazard quotient (THQ), total exposure hazard index (HI), and target carcinogenic risk (TR) indicate no potential risk to humans from whiting fish consumption.

Response of Propsilocerus akamusi (Diptera: Chironomidae) to the leachates from AMD-contaminated sediments: Implications for metal bioremediation of AMD-polluted areas

Acid mine water (AMD) is a global environmental problem caused by coal mining with the characteristics of low pH and high concentrations of metals and sulfates. It is a pertinent topic to seek both economical and environmentally friendly approaches to minimize the harmful effects of AMD on the environment. Insect larvae are considered a promising solution for pollution treatment. Chironomidae is the most tolerant family to contaminants in pools and its larvae have a strong capacity for metal accumulation from sediment. This paper aimed to evaluate the larvae of Propsilocerus akamusi, a dominant species in the chironomid community, as a new species for entomoremediation in AMD-polluted areas. We detected the toxic effects of AMD on P. akamusi larvae based on their survival and the trace metals bioaccumulation capabilities of P. akamusi larvae. Moreover, we analyzed the expression patterns of four stress-response genes, HSP70, Eno1, HbV, and Hb VII in P. akamusi larvae. Our results revealed that AMD exposure did not significantly affect the survival of the P. akamusi larvae and individuals exposed to some AMD gradients even exhibited higher survival. We also observed the significantly accumulated concentrations of Fe, Ni, and Zn as well as higher bioaccumulation factors (BAFs) for Ni and Zn in the P. akamusi larvae exposure to AMD. Induced expression of Eno1 and Hb VII may play important roles in the AMD tolerance of P. akamusi larvae. This study indicated the potential application of P. akamusi larvae in the metal bioremediation of AMD-polluted areas. Statement of environmental implicationAcid mine drainage (AMD) is a global environmental problem related to coal mining activities. AMD pollution has become a long-term, worldwide issue for its interactive and complex stress factors. Bioremediation is an effective method to remove the metals of AMD from wastewater to prevent downstream pollution. However, the disadvantages of the slow growth rate, susceptibility to seasonal changes, difficult post-harvest management, and small biomass of hyperaccumulating plants greatly limit the usefulness of phytoremediation. Insect larvae may be useful candidate organisms to overcome these shortcomings and have been considered a promising pollution solution. Propsilocerus akamusi is a dominant species in the chironomid community and is distributed widely in many lakes of eastern Asia. This species has extraordinary abilities to resist various stresses. This research is the first time to our knowledge to evaluate the application of P. akamusi as a new species in entomoremediation in AMD-contaminated areas.

Strategy matters: Phytoremediation potential of native halophytes is jointly associated with their distinct salt tolerances

Halophytes are effective candidates for phytoremediation of heavy metal-contaminated saline soils. Still, little is known about the relationships between their potential for metal enrichment and salt-tolerance strategies. This study comprehensively investigated the plant community and concentrations and accumulation characteristics of heavy metals (As, Cd, Cr, Cu, Pb, and Zn) in the soil and dominant native plants with different salt-tolerance strategy groups, namely salt-dilution (SD), salt-excretion (SE), salt-exclusion (SC), and non-halophyte, in a semiarid region of Northwest China. The results showed that the soil in this area was primarily polluted by As and Cd, which were 5.80 and 21.18 times higher than the corresponding background values, respectively. The primary vegetation was desert steppe, and 95 species of 34 families were investigated, most of which were herbaceous (64.2%) with the Asteraceae dominating. Eleven of the thirteen dominant plants, except Zea mays and Helianthus annuus, were halophytes with distinct salt tolerances, exhibiting differing metal accumulation and transport capacities. All the bioconcentration factors of the selected species for six metals were lower than 1, and their accumulation ability decreased in the order of Cu (0.466) > Cr (0.315) ≈ Cd (0.093) ≈ Zn (0.082) ≈ As (0.076) > Pb (0.049). Salt-tolerance strategies were significantly correlated with As and Cd accumulations in the soil-plant environment, but in diametrically opposite directions. Also, metal accumulations and translocations partly depended on plant salt resistance strategies. Salt-diluting halophytes such as Suaeda glauca and Kochia scoparia seem applicable for phytoextraction of single or mixed metal pollution, particularly Cd. In comparison, salt-excreting halophytes such as Chenopodium glaucum and Salsola collina would be more suited to As phytostabilization due to the potential for second pollution. In conclusion, SD halophytes could be used in various metal-contaminated soils in salt-affected regions, while SE halophytes would be well suited for phytostabilization. This study would enhance the exploitation advantages of halophyte germplasms with different salt tolerances in multiple-stressed environments.

Assessing the Use of Ziziphus spina-christi as a Sustainable Solution for Biomonitoring of Urban Air Quality: A Case Study from Qatar

Globally, urbanization, industrialization, and transportation have worsened urban air quality in recent decades. Using sustainable, cost-effective methods to monitor and reduce air pollution is crucial. The best Nature-based Solution (NbS) for urban environmental cleanup is plants. Roadside plants are key carriers of air pollution and have various tolerances. Ziziphus spina-christi’s air pollution tolerance was assessed using the Air Pollution Tolerance Index (APTI). The Bioconcentration Factor (BCF) examined the heavy metal accumulation capacity of Ziziphus spina-Christi’s fruits and leaves. Two sampling sites were studied: a reference location remote from human activity and a densely populated metropolitan region. Ziziphus spina-christi is considered a tolerant species in Qatar, based on its calculated value of APTI in this study. Both total chlorophyll and ascorbic acid influence APTI levels and have a strong positive correlation with APTI. BCF values in leaves were higher than fruits indicating that the leaves of Ziziphus spina-christi have a greater potential for metal absorption than its fruits. Moreover, the leaves of Ziziphus spina-christi showed a potential for mercury accumulation (BCF &gt; 1), thus it is a good candidate to be used for phytoremediation in areas of mercury contamination. The integration of both APTI and BCF methods is significant and beneficial in advising policymakers and urban planners regarding suitable tree species for sustainable urban development.

Toxic metals from atmospheric particulate matter in food species of tomato (Solanum lycopersicum) and strawberry (Fragaria x ananassa) used in urban gardening. A closed chamber study

In this work, two plant foods, strawberry and tomato, were subjected to exposure to metals from synthetic airborne particles in a closed chamber experiment. The synthetic particles were obtained in the laboratory. Within the closed chamber, particles were added and recirculated for 4 days in a turbulent air stream, causing deposition on the different parts of the plants. They were evaluated because of their increasingly frequent cultivation in urban gardens of cities. The main objectives were to determine whether the species accumulate metals significantly, which species accumulate the most, and in which parts of the plant. Finally, an attempt was made to differentiate the accumulation of pollutants by surface deposition on leaves and fruits from the adsorbed metals into the leaf or the fruit by their stomata or cuticles. The concentration of heavy metals was quantified in fruits, leaves and the soil after exposure. Metals were evaluated as a whole and individually, both in dry and fresh weight basis. The decrease of particulate matter and metals in the air inside the chamber was also studied in order to evaluate the use of both food species as air purifier by vertical gardens. The concentration of metals in plants (mg kg−1) and airborne particles (mg m−3) was measured by microwave plasma optical emission spectroscopy (MP-AES). For the sake comparison of total amount of metals in the samples concentrations were normalized. Strawberries was the food species that accumulated the largest amount of metals. In a dry weight basis, tomato leaves and strawberry fruits were the parts of the plants with higher accumulation capacity of particles and metals. The potential toxic elements Cd, Ni and Cr in tomato leaves and in strawberry fruits had a higher presence in the interior of the plant system. In a fresh weight basis, the strawberry fruit had the most accumulation capacity for metals.

Effect of different levels of EDTA on phytoextraction of heavy metal and growth of Brassica juncea L.

Heavy metal pollution of soil is a major concern due to its non-biodegradable nature, bioaccumulation, and persistence in the environment. To explore the probable function of EDTA in ameliorating heavy metal toxicity and achieve the sustainable development goal (SDG), Brassica juncea L. seedlings were treated with different concentrations of EDTA (0, 1.0, 2.0, 3.0, and 4.0 mM Kg-1) in heavy metal-polluted soil. Plant samples were collected 60 days after sowing; photosynthetic pigments, H2O2, monoaldehyde (MDA), antioxidant enzymes, and ascorbic acid content, as well as plant biomass, were estimated in plants. Soil and plant samples were also examined for the concentrations of Cd, Cr, Pb, and Hg. Moreover, values of the phytoremediation factor were utilized to assess the accumulation capacity of heavy metals by B. juncea under EDTA treatments. In the absence of EDTA, B. juncea seedlings accrued heavy metals in their roots and shoots in a concentration-dependent manner. However, the highest biomass of plants (roots and shoots) was recorded with the application of 2 mM kg-1 EDTA. Moreover, high levels (above 3 mM kg-1) of EDTA concentration have reduced the biomass of plants (roots and shoots), photosynthetic area, and chlorophyll content. The effect of EDTA levels on photosynthetic pigments (chlorophyll a and b) revealed that with an increment in EDTA concentration, accumulation of heavy metals was also increased in the plant, subsequently decreasing the chlorophyll a and b concentration in the plant. TLF was found to be in the order Pb> Hg> Zn> and >Ni, while TF was found to be in the order Hg>Zn>Ni>Pb, and the best dose was 3 mM kg-1 EDTA for Hg and 4 mM kg-1 for Pb, Ni, and Zn. Furthermore, hyperaccumulation of heavy metals enhanced the generation of hydrogen peroxide (H2O2), superoxide anions (O2•-), and lipid peroxidation. It also interrupts mechanisms of the antioxidant defense system. Furthermore, heavy metal stress reduced plant growth, biomass, and chlorophyll (chl) content. These findings suggest that the exogenous addition of EDTA to the heavy metal-treated seedlings increases the bioavailability of heavy metals for phytoextraction and decreases heavy metal-induced oxidative injuries by restricting heavy metal uptake and components of their antioxidant defense systems.

Coastal Wetland Species Rumex hydrolapathum: Tolerance against Flooding, Salinity, and Heavy Metals for Its Potential Use in Phytoremediation and Environmental Restoration Technologies.

Plants with high biomass adapted to conditions of increased moisture and with significant salt tolerance appear to be particularly attractive candidates for phytoremediation studies. The aim of the present study was to examine the tolerance of Rumex hydrolapathum plants to freshwater, saltwater inundation, and soil contaminated with heavy metals, as well as its metal accumulation potential in controlled conditions. Six separate vegetation container experiments in controlled conditions were performed with R. hydrolapathum plants to study the effects of soil moisture, waterlogging with NaCl, soil Cd, soil Cr, soil Ni, and soil Pb in the form of a nitrate or acetate. Optimum plant growth occurred in waterlogged soil conditions. As the concentration of NaCl used for waterlogging increased, the mass of living leaves decreased, but that of dry leaves increased. As a result, the total biomass of leaves did not significantly change. R. hydrolapathum plants were extremely tolerant to Cd and Pb, moderately tolerant to Ni, and relatively sensitive to Cr. The plants had high capacity for metal accumulation in older and senescent leaves, especially for Na+, K+, Cd, and Ni. R. hydrolapathum plants can tolerate soil waterlogging with seawater-level salinity, which, together with the metal tolerance and potential for metal accumulation in leaves, make them excellently suited for use in a variety of wastewater treatment systems, including constructed wetlands.

Comparison of Machine Learning Models in the Prediction of Accumulation of Heavy Metals in the Tree Species in Kanchipuram, Tamilnadu

Arsenic, aluminum, iron, lead, chromium, copper, zinc, manganese, and cadmium are some of the heavy metal pollutants in the air that cause severe impacts on the biotic and abiotic environment. This study intended to find the accumulation capacity of the heavy metals on the leaves of tree species such as Terminalia catappa, Syzygium cumini, Saraca asoca, Pongamia glabra, and Ficus religiosa and predict their accuracy by comparing different machine learning (ML) models. The samples were collected at six different locations (likely Vellagate, Cancer Institute, CSI hospital area, Moongilmandapam, Collectorate, and Pallavarmedu) and distributed in a manner within Kanchipuram town, Tamil Nadu, in February and March of 2018 and 2019, respectively. Six ML methods were selected, such as KStar (K*), Lazy IKB, Logistic Regression Algorithm (LR), LogitBoost Classifier (LB), Meta Randomizable Filtered Classifier (MRFC), and Random Tree (RT), for prediction and to compare the efficiency of their predictions. Out of six models, Logistic functions perform well in terms of TP rate when compared to other classifiers (93.21%-99.81% TPR– 0.93–0.99) and Logitboost attained a low TP rate that ranged from 0.76 to 0.82. This study indicates the feasibility of different ML methods in the prediction of species capabilities toward the accumulation of heavy metals.

Stable Artificial Autopolyploids of the Zn/Cd Accumulator Arabidopsis arenosa—A Promising Genetic Resource for Phytoremediation

Arabidopsis arenosa is a good candidate for phytoremediation due to its high tolerance to Zn and Cd as well as its accumulation ability. However, its small size and low biomass are the largest obstacles to applying it on a broad scale. The aim was to obtain polyploid specimens, which tend to have higher biomass to increase the accumulation and translocation capacity of heavy metals in this metal-tolerant plant. Doubled polyploids (octaploids) were obtained via indirect organogenesis on a ½ MS medium supplemented with 1 mg L−1 TDZ, followed by rooting on the same medium without growth regulators. Callus tissue of a high endopolyploidy level (the (Ʃ&gt;2C)/2C ratio over 2.5) obtained on seedling fragments on ½ MS supplemented with 2 mg L−1 2,4-D + 2 mg L−1 BAP served as a source material. Among the regenerants successfully obtained (without using antimitotic agents), over half, regardless of the stage of regenerant development, were octaploid (54–78%; 2C DNA = 1.642 pg). Octaploids were not affected by ploidy or in vitro culture conditions; they were fully fertile, produced normal pollen (~97% of viability), and set seeds capable of germinating (78%). Their cell and organ size was affected by genome doubling resulting in longer stomata, bigger pollen grains, and flowers with a larger area and width in comparison with tetraploid regenerants and initial plants. The promising results of measurements of morpho-anatomical, physiological, and reproductive parameters indicate that, in the future, after passing tolerance tests, the obtained polyploids could be used in phytoremediation of metal-contaminated areas.

Phytoremediation technologies and their mechanism for removal of heavy metal from contaminated soil: An approach for a sustainable environment.

The contamination of soils with heavy metals and its associated hazardous effects are a thrust area of today's research. Rapid industrialization, emissions from automobiles, agricultural inputs, improper disposal of waste, etc., are the major causes of soil contamination with heavy metals. These contaminants not only contaminate soil but also groundwater, reducing agricultural land and hence food quality. These contaminants enter the food chain and have a severe effect on human health. It is important to remove these contaminants from the soil. Various economic and ecological strategies are required to restore the soils contaminated with heavy metals. Phytoremediation is an emerging technology that is non-invasive, cost-effective, and aesthetically pleasing. Many metal-binding proteins (MBPs) of the plants are significantly involved in the phytoremediation of heavy metals; the MBPs include metallothioneins; phytochelatins; metalloenzymes; metal-activated enzymes; and many metal storage proteins, carrier proteins, and channel proteins. Plants are genetically modified to enhance their phytoremediation capacity. In Arabidopsis, the expression of the mercuric ion-binding protein in Bacillus megaterium improves the metal accumulation capacity. The phytoremediation efficiency of plants is also enhanced when assisted with microorganisms, biochar, and/or chemicals. Removing heavy metals from agricultural land without challenging food security is almost impossible. As a result, crop selections with the ability to sequester heavy metals and provide food security are in high demand. This paper summarizes the role of plant proteins and plant-microbe interaction in remediating soils contaminated with heavy metals. Biotechnological approaches or genetic engineering can also be used to tackle the problem of heavy metal contamination.

Examination of the Metallothionein Gene Family in Greater Duckweed Spirodela polyrhiza.

Duckweeds are aquatic plants that proliferate rapidly in a wide range of freshwaters, and they are regarded as a potential source of sustainable biomass for various applications and the cost-effective bioremediation of heavy metal pollutants. To understand the cellular and molecular basis that underlies the high metal tolerance and accumulation capacity of duckweeds, we examined the forms and transcript profiles of the metallothionein (MT) gene family in the model duckweed Spirodela polyrhiza, whose genome has been completely sequenced. Four S. polyrhiza MT-like genes were identified and annotated as SpMT2a, SpMT2b, SpMT3, and SpMT4. All except SpMT2b showed high sequence homology including the conserved cysteine residues with the previously described MTs from flowering plants. The S. polyrhiza genome appears to lack the root-specific Type 1 MT. The transcripts of SpMT2a, SpMT2b, and SpMT3 could be detected in the vegetative whole-plant tissues. The transcript abundance of SpMT2a was upregulated several-fold in response to cadmium stress, and the heterologous expression of SpMT2a conferred copper and cadmium tolerance to the metal-sensitive ∆cup1 strain of Saccharomyces cerevisiae. Based on these results, we proposed that SpMT2a may play an important role in the metal detoxification mechanism of duckweed.