Phytoremediation Capacity Research Articles

Effect of Adaptation to High Concentrations of Cadmium on Soil Phytoremediation Potential of the Middle European Ecotype of a Cosmopolitan Cadmium Hyperaccumulator Solanum nigrum L.

The Cd hyperaccumulator Solanum nigrum L. exhibits a cosmopolitan character and proven high and differentiated efficiency. This suggests the possibility of optimizing its Cd phytoremediation capacity and applicability through searching among remote ecotypes/genotypes. However, the extensive studies on this hyperaccumulator have been limited to Far East (Asian) regions. Pioneer pot experiments on the Middle European ecotype of S. nigrum within a concentration range of 0–50 mg kg−1 Cd in soil revealed its Cd phytoremediation capacity to be comparable to Asian ecotypes but with a fundamentally different Cd tolerance threshold. While biomass of the Asian ecotypes declined sharply at Csoil ≈ 10 mg kg−1 Cd, in the Middle European ecotype, a gradual mild biomass decrease occurred within the whole Csoil ≈ 0–50 mg kg−1 Cd range with no toxic symptoms. Its adapted A50 variety was obtained from the seeds of first-generation plants grown in soil with Csoil ≈ 50 mg kg−1 Cd. In this variety, Cd tolerance, accumulation performance, and all physiological parameters (chlorophyll, carotenoids, RuBisCO, and first- and second-line defense anti-oxidant activity) were significantly enhanced, while cell damage by ROS was considerably lesser. This makes the Middle European ecotype and its adapted variety A50 particularly useful to sustainable decontamination of heavily polluted “hot spots” in degraded post-industrial areas.

Impact of two arbuscular mycorrhizal fungi species on arsenic tolerance and accumulation in safflower (Carthamus tinctorius L.)

BackgroundArbuscular mycorrhizal fungi (AMF) can regulate metal(loid) tolerance in plants and their capacity for phytoremediation. These effects can vary depending on the host plant and the AMF species. The impact of different AMF species on the ability of safflower (Carthamus tinctorius L.) for arsenic (As) phytoremediation is still largely unknown. Therefore, this study aimed to assess the effect of two AMF species, Rhizophagus irregularis, and Funneliformis mosseae, on the tolerance and accumulation of As in safflower in soils spiked with varying arsenate concentrations (0, 25, 50, and 100 mg kg−1).ResultsThe results indicated that both AMF species established effective symbiotic relationships with safflower. However, plants inoculated with R. irregularis exhibited higher mycorrhizal dependency and root colonization, especially under 100 mg kg−1 As. Both AMF species significantly improved plant growth parameters, chlorophyll content, and phosphorus (P) nutrition, which resulted in increased P/As ratio and enhanced tolerance index in safflower plants. In addition, AMF inoculation reduced As-induced lipid peroxidation by enhancing catalase and peroxidase activity in leaves and roots. While the mycorrhizal symbiosis didn’t affect As availability in soils, it significantly reduced shoot As concentration and the translocation factor under all As levels. Furthermore, mycorrhizal inoculation, especially with R. irregularis, increased As concentration and modified-bioconcentration factor in the roots and enhanced total As uptake per plant.ConclusionsBased on the results and multivariate analyses, both AMF species, particularly R. irregularis, enhanced safflower's As tolerance by retaining As in roots, improving phosphorus nutrition, and increasing antioxidant enzyme activity, showcasing their potential to enhance phytostabilization in safflower plants.

Heavy metal phytoremediation potential of Cosmos bipinnatus for use in chromium-contaminated regions of Dravyavati River, Jaipur, Rajasthan, India.

Due to their toxicity and permanence, heavy metals pose a significant threat as pollutants. Metals leach into soil from human activities including mining, manufacturing, and farming. Phytoremediation involves removing contaminants from soils using herbaceous plants and trees; it is a cost-effective, non-invasive, and aesthetically pleasing technique. The current research investigated the phytoremediation capacity of Cosmos bipinnatus in soil that had been polluted with chromium (Cr) along the Dravyavati River in Jaipur. The plant uptake of heavy metals was studied for 20, 40, 60, and 80 days of growth in pot and field experiments using atomic absorption spectrophotometry (AAS) to analyze residual heavy metal concentrations in the plant's shoots and roots. Chromium exhibited variation in total absorption by plants depending on the type of treatment. Using the translocation factor, it was observed that after 80 days in Nala soil 80% + wheat husk 20% (H2), the plant's capacity to absorb Cr was equivalent and considerably higher. Nola soil 80% + wheat husk 20%; H2, and Nala soil 70% + wheat husk 30%; H3 were among the treatments with TFs more than 1; however, the BCF values were all lower than 1. Additionally, root uptake was greater than shoot uptake. Thus, at H3 and H2 treatments, C. bipinnatus was determined to be an efficient phytoextractor for Cr, but at other concentrations, it acted as an excluder.

Heavy Metals and Associated Risks of Wild Edible Mushrooms Consumption: Transfer Factor, Carcinogenic Risk, and Health Risk Index

This research aims to investigate the heavy metals (i.e., Cd, Cr, Cu, Ni, and Pb) in the fruiting bodies of six indigenous wild edible mushrooms including Agaricus bisporus, Agaricus campestris, Armillaria mellea, Boletus edulis, Macrolepiota excoriate, and Macrolepiota procera, correlated with various factors, such as the growth substrate, the sampling site, the species and the morphological part (i.e., cap and stipe), and their possible toxicological implications. Heavy metal concentrations in mushroom (228 samples) and soil (114 samples) were determined by Inductively Coupled Plasma—Mass Spectrometry (ICP-MS). In the first part of the study, the soil contamination (index of geo-accumulation, contamination factor, and pollution loading index) and associated risks (chronic daily dose for three exposure pathways—ingestion, dermal, and inhalation; hazard quotient of non-cancer risks and the carcinogenic risks) were calculated, while the phytoremediation capacity of the mushrooms was determined. At the end of these investigations, it was concluded that M. procera accumulates more Cd and Cr (32.528% and 57.906%, respectively), M. excoriata accumulates Cu (24.802%), B. edulis accumulates Ni (22.694%), and A. mellea accumulates Pb (18.574%), in relation to the underlying soils. There were statistically significant differences between the stipe and cap (i.e., in the cap subsamples of M. procera, the accumulation factor for Cd was five times higher than in the stipe subsamples). The daily intake of toxic metals related to the consumption of these mushrooms with negative consequences on human health, especially for children (1.5 times higher than for adults), was determined as well.

Evaluating the productivity of five forages for the phytoremediation of heavy metal-contaminated land

Post-tin mining land holds promise for cultivating forage crops, with the potential to address Pb metal contamination through plant-based phytoremediation. However, the presence of heavy metals and depleted soil fertility resulting from tin mining activities may pose challenges to plant productivity and contribute to residual heavy metal accumulation. This study aims to assess the productivity and phytoremediation capacity of Pb by various grass species on reclaimed mining land. Using a randomised block design with three replications, the study was conducted over a four-year period in a post-mining area in Central Bangka Regency, Indonesia. Three grass species: Megathyrsus maximus (‘Riversdale’ and ‘Purple guinea’), Pennisetum purpureum (‘Taiwan’ and ‘Mott’), and Chrysopogon zizanioides were evaluated for forage production, quality, digestibility, and heavy metal content. It was shown that ‘Riversdale’ and ‘Purple guinea’ cultivars had relatively stable production for over four years, with the crude protein content of all grass types remaining relatively low (<6%), apart from ‘Mott’ cultivar, which had a crude protein content of 10%. The Pb concentration in the plants remained below the permitted limits for ruminants. In the post-tin mining site, ‘Riversdale’ and ‘Purple guinea’ cultivars showed potential for development. It is concluded that mined land can be replanted with forage crops for phytoremediation purposes. ‘Purple guinea’ and ‘Riversdale’ cultivars emerge as potential livestock feed sources on ex-mining land due to their four-year productive stability and low lead (Pb) concentration in their shoots, which falls below the safe threshold for cattle.

Biological Wastewater Treatment Using Higher Aquatic Plants

This article presents the results of research on the biological treatment of various industrial and domestic wastewater using higher aquatic plants. The experiments examined the possibility of biological treatment of mining wastewater on a semi-industrial scale using <i>Eichhornia crassipes </i>Solms, <i>Pistia stratiotes</i> L. <i>Azolla</i> <i>caroliniana </i>and <i>Lemna minor </i>and their features in biological treatment are identified. Eichhornia and pistia plants are important because they show high efficiency in wastewater treatment due to their high adsorption properties, with frequent renewal of biomass in ponds, the phytoremediation capacity of higher aquatic plants is 51% per day due to the adsorption properties of plants, based on calculations, it is possible to propose cleaning pools with a volume of 1000 cubic meters of water for 5 days, through the renewal of plant culture every 1-3 days. The use of purification methods in this way recommends the construction of additional structures. In this case, depending on the volume of wastewater from the plant, it is necessary to build additional bioponds, create a water transfer system, and also build additional bioponds for the purpose of growing biomass or increasing plants. Only then can the biological purification method we recommend be used on an industrial scale or at an industrial enterprise to purify wastewater in an environmentally safe and cost-effective manner.

Impacts of Organic Amendments on the Phytoremediation Capacities of Two Salicaceae Taxa

Impacts of Organic Amendments on the Phytoremediation Capacities of Two Salicaceae Taxa

Tolerance and phytoremediation capacity of atrazine and S-metolachlor by two duckweeds.

The phytotoxicity and removal of atrazine and S-metolachlor in sterile duckweed systems were estimated in this study. Herbicides were added at environmentally relevant ranges: 0-400µg/L for atrazine or 0-200µg/L for S-metolachlor in systems with Spirodela polyrhiza or Lemna minor. Toxicity biomarkers, i.e., changes in plant biomass, surface area, chlorophyll fluorescence parameters, pigments, lipid peroxidation, protein concentration, and antioxidative enzyme activities in plants were estimated after 7days. S. polyrhiza (RGRbiomass-EC50 = 164.8µg/L) was more tolerant to atrazine than L. minor (RGRbiomass-EC50 = 101.0µg/L). Atrazine caused damage to photosystem II (ΦM), a reduction in electron transport between PSII and PSI (Φ'M), as well as disruption in energy distribution pathways (decrease in qPrel and increase in UQFrel), most prominently in L. minor. However, L. minor (RGRbiomass-EC50 = 128.9µg/L) was more tolerant to S-metolachlor than S. polyrhiza (RGRbiomass-EC50 = 15.5μg/L). The highest sensitivity of S. polyrhiza to S-metolachlor was attributed to a decrease in absorbed energy used in photochemistry (qPrel) and an increase in lipid peroxidation, indicating that S. polyrhiza plants were experiencing oxidative stress. Residual pesticide analysis in the water after seven days allowed us to conclude that plants were responsible for reducing up to 16.5% of atrazine and 28.7% of S-metolachlor in the duckweed system. S. polyrhiza showed higher atrazine phytoremediation capacity than L. minor. S. polyrhiza was more efficient at an environmentally relevant concentration of S-metolachlor (25μg/L) and L. minor at higher concentrations (200μg/L).

Use of Cannabis sativa L. for Improving Cadmium-Contaminated Mediterranean Soils—Effect of Mycorrhizal Colonization on Phytoremediation Capacity

Although the phytoremediation strategy has been studied worldwide, little research data are available regarding the influence of mycorrhizae on the phytoremediation capacity of various plants grown in Cd-contaminated soils in Mediterranean environments. Therefore, a pot experiment was carried out to study the possible effectiveness of hemp plant (Cannabis sativa L.) in the remediation of moderately and heavily Cd-contaminated soils and additionally to quantify the effect of Cd on Arbuscular Mycorrhizal Fungi (AMFs). For this purpose, an alkaline clay soil collected from the Farm of Institute of Plant Breeding and Genetic Resources (North Greece) was contaminated with two levels of Cd (3 and 30 mg Cd kg−1, corresponding to Levels A and B, respectively—first factor) at two incubation times (10 and 30 days—second factor) and six treatments (Control_30d, Control_10d, CdA_30d, CdB_30d, CdA_10d, CdB_10d) were created. Soil Cd concentrations, both pseudo-total and available to plants, were determined after extraction with Aqua Regia mixture and DTPA solution, respectively, before and after the cultivation of hemp plants and after the harvesting. Cd concentrations in the aboveground and underground plant parts were also estimated after digestion with Aqua Regia, while root colonization by AMFs was determined with a microscope. The highest plant’s Cd concentration, more than 50%, was observed in its underground part, at all Cd-contaminated treatments, indicating a strong capacity for cadmium to gather up in the roots. Among different Cd levels and incubation days, significant differences were recorded in the rates of root colonization by AMFs. Among different Cd levels and incubation days, 3 mg Cd Kg−1 soil promoted AMF root colonization, particularly at 10-day incubation, while 30 mg Cd Kg−1 soil diminished it. Colonization was lower with longer incubation times at both levels of Cd. Hemp appears to be a viable option for phytostabilization in Cd-contaminated soils, enabling further utilization of AMFs to assist the phytoremediation process.

Cytotoxicity, chemical, and nutritional profile evaluation of biomass extracts of the Lemna aequinoctialis (duckweed) aquatic plant

ABSTRACT Lemna aequinoctialis (duckweed) is the smallest and fast-growing aquatic plant species producing protein-rich biomass with high protein nutritional value, phytoremediation capacity, and nutrient removal from wastewater. Duckweed may also be used as a new potential bioreactor for biological products, such as vaccines, antibodies, and pharmaceutical proteins. Based upon the potential importanc of L. aequinoctialis in phytoremediation and as a bioreactor the aim of this study was to (1) characterize the chemical and nutritional profiles of L. aequinoctialis biomass utilizing an integrated multi-trophic aquaculture system (IMTA) and a pond, and (2) investigate the cytotoxic potential of different concentrations of organic extracts and fractions using the MTT bioassay. EDXRF and ICP-MS analyses indicated the presence of trace elements in lower amounts in relation to the biomass of L. aequinoctialis in the lagoon, emphasizing the importance of plant inclusion management to reduce bioaccumulation of these elements. Analysis of mineral profiles, fatty acids, and amino acids indicated a satisfactory nutritional composition for the use of biomass as a bioproduct. Pigment analysis showed a high concentration of carotenoids, especially astaxanthin. After standardizing the controls, the MTT cell viability test was carried out utilizing rat hepatoma cell line (HTC), which are metabolizing cells that were treated with aqueous or ethanolic extracts and the dichloromethane, ethyl acetate, and methanol fractions at different concentrations. No apparent cytotoxic potential was observed following treatments, since there was no significant reduction in cell viability. Therefore, this study provides information regarding the biomass of L. aequinoctialis derived from the IMTA system, which might support further research into the application of this species as a bioproduct.

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.

The impact of shade net use on total nitrogen removal by duckweed (Lemna perpusilla) at different levels of catfish farming effluent

Duckweed (Lemna perpusilla) has been shown to reduce nutrient levels in aquaculture effluent, particularly total nitrogen, which can be caused by a variety of organic contaminants in water. Duckweed biomass is an important source of bioenergy and phytoremediation in aquaculture. This aspect makes it a viable solution for sustainable integrated aquaculture, although appropriate duckweed biomass development is critical to its success and long-term survival. Duckweed growth, as an autotroph, is controlled by two factors: nutrition and sunlight. The aquaculture production cycle changes nutrient content in medium culture based on feed, fish age, and density, while weather influences solar radiation. The study aims to investigate duckweed growth response and phytoremediation capacity by analyzing changes in catfish farming waste-water quality grouped by fish age (L1: 2 months, L2: 3 months, and L3: 4 months) and shade net treatment at 25 % sunlight blocking (N25), 50 % (N50), and no shade net (N0). The experiment was carried out in triplicate in a semi-outdoor growth system placed in a greenhouse. It comprised of three series of duckweed culture containers filled with catfish farming wastewater, each with a working volume of 50 L. A total of 48 duckweed culture containers were floated inside a series of Recirculating Aquaculture System (RAS) tanks. Biomass harvesting and water quality monitoring were done every three days for a period of 18 days. N25 had the highest biomass weight, productivity, and average TN elimination efficiency, with values of 225.21 ± 140.04 g, 50.05 ± 10.06 g/(m2.d), and 61.94 ± 8.01 %, respectively (P < 0.05). The N0 values were 190.80 ± 117.52 g, 42.40 ± 9.29 g/(m2.d), and 55.61 ± 6.85 % (P < 0.05). The lowest values observed in N50 were 72.27 ± 55.70 g, 16.06 ± 4.90 g/(m2.d), and 51.67 ± 4.10 % (P < 0.05). This study proved the optimal duckweed growth and TN removal effectiveness with N25 under varying light intensity, allowing for the long-term use of duckweed in waste management and integrated aquaculture.

Biotechnological approaches for enhancement of heavy metal phytoremediation capacity of plants.

Heavy metals are extremely hazardous for human health due to their toxic effects. They are non-biodegradable in nature, thus remain in the environment and enter and accumulate in the human body through biomagnification; hence, there is a serious need of their remediation. Phytoremediation has emerged as a green, sustainable, and effective solution for heavy metal removal and many plant species could be employed for this purpose. Plants are able to sequester substantial quantity of heavy metals, in some cases thousands of ppm, due to their robust physiology enabling high metal tolerance and anatomy supporting metal ion accumulation. Identification and modification of potential target genes involved in heavy metal accumulation have led to improved phytoremediation capacity of plants at the molecular level. The introduction of foreign genes through genetic engineering approaches has further enhanced phytoremediation capacity manifolds. This review gives an insight towards improving the phytoremediation efficiency through a better understanding of molecular mechanisms involved, expression of different proteins, genetic engineering approaches for transgenic production, and genetic modifications. It also comprehends novel omics tools such as genomics, metabolomics, proteomics, transcriptomics, and genome editing technologies for improvement of phytoremediation ability of plants.

Enhancing the phytoremediation efficiency of Bacopa monnieri (L.) Wettst. using LED lights: a sustainable approach for heavy metal pollution control.

In this study, the impacts of LEDs on the phytoremediation of arsenic (As) and mercury (Hg) by Bacopa monnieri (L.) Wettst. were investigated, along with the examination of the biochemical characteristics of plants exposed to metal-induced toxicity. In vitro multiple and rapid plant propagations were successfully achieved by adding 1.0mg/L 6-Benzyl amino purine (BAP) to the Murashige and Skoog (MS) basal salt and vitamin culture medium. For plant-based remediation experiments, different concentrations of As (0-1.0mg/L) and Hg (0-0.2mg/L) were added to the water environment, and trials were conducted for four different application periods (1-21days). White, red, and blue LEDs, as well as white fluorescent light, were preferred as the light environment. The results revealed that LED lights were more effective for heavy metal accumulation, with red LED light significantly enhancing the plant's phytoremediation capacity compared to other LED applications. Moreover, when examining biochemical stress parameters such as levels of photosynthetic pigments, protein concentrations, and lipid peroxidation, plants under red LED light showed better results. Generally, the lowest results were obtained under white fluorescent light. These findings contribute to phytoremediation studies by highlighting the integration of LED lights, thereby enabling the development of a more effective, cost-efficient, and environmentally sustainable remediation system compared to other treatment methods.

Ectopic expression of the yeast Mn2+ transporter SMF2 enhances tolerance and resistance to cadmium and arsenic in transgenic Arabidopsis

Vesicular sequestration is a potential strategy for enhancing plant tolerance to cadmium (Cd) and arsenic (As). In this study, the ectopic overexpression of yeast-derived ScSMF2 in Arabidopsis thaliana was found to enhance the accumulation and tolerance of Cd and As in transgenic plants. ScSMF2 was localized on vacuole membranes and formed puncta structures in plant cells when agro-infiltrated for transient expression. Transgenic Arabidopsis showed less retardation on root elongation and shoot weight and more accumulation of Cd, As (III) and As (V) when cultured on medium containing Cd or As. Overexpression of ScSMF2 promoted accumulation of Cd and arsenic in transgenic Arabidopsis, which were over twice higher than in WT plants when cultured in soil. This study provides insights into the mechanisms involved in the vesicular sequestration of heavy metals in plant and presents a potential strategy for enhancing the phytoremediation capacity of plants toward heavy metals.

Green solutions for antibiotic pollution: Assessing the phytoremediation potential of aquatic macrophytes in wastewater treatment plants

We compared the ability of one emergent (Sagittaria montevidensis), two floating (Salvinia minima and Lemna gibba), and one heterophyllous species (Myriophyllum aquaticum) to simultaneously remove sulfamethoxazole, sulfadiazine, ciprofloxacin, enrofloxacin, norfloxacin, levofloxacin, oxytetracycline, tetracycline, doxycycline, azithromycin, amoxicillin, and meropenem from wastewater in a mesocosm-scale constructed wetland over 28 days. Antibiotic concentrations in plants and effluent were analyzed using an LC-MS/MS to assess the removal rates and phytoremediation capacities. M. aquaticum did not effectively mitigate contamination due to poor tolerance and survival in effluent conditions. S. minima and L. gibba demonstrated superior efficiency, reducing the antibiotic concentrations to undetectable levels within 14 days, while S. montevidensis achieved this result by day 28. Floating macrophytes emerge as the preferable choice for remediation of antibiotics compared to emergent and heterophyllous species. Antibiotics were detected in plant tissues at concentrations ranging from 0.32 to 29.32 ng g−1 fresh weight, highlighting macrophytes' ability to uptake and accumulate these contaminants. Conversely, non-planted systems exhibited a maximum removal rate of 65%, underscoring the persistence of these molecules in natural environments, even after the entire experimental period. Additionally, macrophytes improved effluent quality regardless of species by reducing total soluble solids and phosphate concentrations and mitigating ecotoxicological effects. This study underscores the potential of using macrophytes in wastewater treatment plants to enhance overall efficiency and prevent environmental contamination by antibiotics, thereby mitigating the harmful impact on biota and antibiotic resistance. Selecting appropriate plant species is crucial for successful phytoremediation in constructed wetlands, and actual implementation is essential to validate their effectiveness and practical applicability.

Bio-stimulating effect of endophytic Aspergillus flavus AUMC 16068 and its respective ex-polysaccharides in lead stress tolerance of Triticum aestivum plant

Heavy metal accumulation is one of the major agronomic challenges that has seriously threatened food safety. As a result, metal-induced phytotoxicity concerns require quick and urgent action to retain and maintain the physiological activities of microorganisms, the nitrogen pool of soils, and the continuous yields of wheat in a constantly worsening environment. The current study was conducted to evaluate the plant growth-promoting endophytic Aspergillus flavus AUMC 16,068 and its EPS for improvement of plant growth, phytoremediation capacity, and physiological consequences on wheat plants (Triticum aestivum) under lead stress. After 60 days of planting, the heading stage of wheat plants, data on growth metrics, physiological properties, minerals content, and lead content in wheat root, shoot, and grains were recorded. Results evoked that lead pollution reduced wheat plants’ physiological traits as well as growth at all lead stress concentrations; however, inoculation with lead tolerant endophytic A. flavus AUMC 16,068 and its respective EPS alleviated the detrimental impact of lead on the plants and promoted the growth and physiological characteristics of wheat in lead-contaminated conditions and also lowering oxidative stress through decreasing (CAT, POD, and MDA), in contrast to plants growing in the un-inoculated lead polluted dealings. In conclusion, endophytic A. flavus AUMC 16,068 spores and its EPS are regarded as eco-friendly, safe, and powerful inducers of wheat plants versus contamination with heavy metals, with a view of protecting plant, soil, and human health.

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

Phytoremediation capacity of hybrid aspen at sites affected by industry and agriculture.

Fast-growing Populus spp. are well-acknowledged to restore contaminated soils from heavy metals in industrial areas. Thus far, there is no knowledge about the phytoremediation capacity of Populus spp. plantations in hemiboreal Estonia conditions to restore industrially polluted areas. The objective of this study was to assess the soil contamination rate of heavy metals (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) and their uptake by mature hybrid aspen (Populus tremula × Populus tremuloides Michx.) in plantations in different industrial pollution areas (e.g. cement factory, oil shale mining). For the reference, industrially polluted plantations were compared with the low pollution area hybrid aspen plantation on former agricultural soil, which was influenced by fertilization and liming before afforestation. Twenty-one years after afforestation, soil samples were collected from the 0-10cm topsoil layer. Aboveground biomass sampling was performed for bark and stem wood by ingrowth cores to separate wood formed during early (1-10years) and late (11-21years) stand development. Two decades after the afforestation of industrially polluted areas, the heavy metal concentrations in the soil were higher than the reference plantation and the standard reference for unpolluted soils in most cases. The highest concentrations of heavy metals in woody biomass were in the oil shale quarry spoil; because of poor growth, the accumulated pools in aboveground biomass were low. Cd differed from other metals and accumulated less in wood and more in bark. The concentration of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni and Zn) was higher in the first decade of stand formation (1-10years) than in the last 10years (11-21years). High pools of heavy metals were accumulated in aboveground biomass in the reference plantation, indicating the considerable removal of heavy metal residues from the previous fertilization and liming source with harvest. Two decades of afforestation with hybrid aspen is too short for complete ecosystem restoration from heavy metals in industrially polluted areas.

Metal-rich biochar as an asphalt modifier to improve sustainability and reduce VOC emissions

Asphalt-surfaced areas have been recently reported as non-combustion sources emitting organic chemical compounds. These emissions from asphalt not only accelerate its aging but also negatively affect air quality and the health of people who inhale the emitted compounds. Trying to mitigate the latter emission and inspired by the phytoremediation capacity of the acacia plant, we have developed a metal-rich carbonaceous adsorbent (biochar) from the acacia plant. Here, we evaluate the efficacy of our acacia-derived adsorbent to reduce the hazardous volatile organic compounds (VOCs) emitted from asphalt-surfaced areas. We further compare the efficacy of our acacia-derived adsorbent with an adsorbent made from a low-metal plant (silver grass). The higher metal content of the adsorbent made from acacia correlated with its higher efficacy compared to that of silver grass in reducing the release of VOCs from the corresponding asphalt, displaying emissions of 16.9% in asphalt binder containing acacia biochar compared to emissions of 21.2% using silver-grass biochar. Using density functional theory (DFT)-based molecular modeling, we specifically investigated the adsorption behavior of three prominent metals present in acacia biochar: Ca with ≈8 wt%, Al with 6.9 wt%, and Fe with 4.4 wt%. Using DFT, we demonstrated the individual contribution of each metal to adsorbing each of six chemical air pollutants. The DFT results revealed the superiority of Fe at interacting with VOCs across all N-containing zones of the biochar surface: pyridine, pyrrole, amine, and amide. Specifically, in the pyridine and pyrrole zones of the biochar surface, the trend of interaction energy for gas pollutants is as follows: Fe > Ca > Al > no metal. Considering the high concentration of Ca in acacia biochar (≈8 wt%), this trend of energy (Fe > Ca > Al > no metal) highlights the crucial role of Ca in enhancing biochar adsorption. Our findings highlight the potential of using inherently metal-rich biomass feedstocks to reduce volatile emissions from asphalt-surfaced areas, improving air quality and extending the service life of roadway infrastructure.