Metal Uptake Efficiency Research Articles

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.

Differential growth and metal uptake efficiency of castor bean genotypes on a lead contaminated soil

<p>Present study investigated the unknown responses of five castor bean genotypes to lead (Pb) contaminated soil, focusing on their growth and metal uptake efficiency. A unique aspect is the simultaneous assessment of multiple genotypes, offering a holistic view of their reactions to soil contamination. Five castor genotypes (NIAB Gold, NIAB Spineless, NIAB-2020, DS-30, and C-3) were grown in pots filled with soil spiked with varying concentrations of Pb (0, 100, 200, 400, and 800 mg kg-1). Results have shown that increasing Pb concentrations led to a general decrease in plant biomass and photosynthetic pigments in all castor genotypes, however NIAB-2020 and DS-30 showcased remarkable resilience. Interestingly, the activities of antioxidant enzymes revealed a contrasting pattern. While superoxide dismutase and peroxidase activity declined, catalase and ascorbate peroxidase activity increased with higher Pb levels. Notably, DS-30 and NIAB-2020 exhibited the maximum catalase and ascorbate peroxidase activity at highest Pb concentration. Furthermore, these genotypes displayed impressive Pb uptake, particularly in their roots, exceeding the other tested genotypes. With metal translocation factor less than 1, NIAB-2020 and DS-30 showed promising potential for phytostabilization through efficient Pb accumulation, coupled with strengthened antioxidant defense mechanisms and restricted translocation, making them compelling candidates for eco-friendly remediation strategies.</p>

Differential growth and metal uptake efficiency of castor bean genotypes on a lead contaminated soil

Differential growth and metal uptake efficiency of castor bean genotypes on a lead contaminated soil

Soil water stress alters differentially relative metabolic pathways affecting growth performance and metal uptake efficiency in a cadmium hyperaccumulator ecotype of Sedum alfredii.

Modeling plants for biomass production and metal uptake from surrounding environment is strongly dependent on the moisture content of soil. Therefore, experiments were conducted to find out how soil moisture affects the phenotypic traits, photosynthetic efficiency, metabolic profile, and metal accumulation in the hyperaccumulating ecotype of Sedum alfredii (S. alfredii). A total of six water potential gradients were set: 0 ~ -15 kPa (T1), -15 ~ -30 kPa (T2), -30 ~ -45 kPa (T3), -45 ~ -60 kPa (T4), -60 ~ -75 kPa (T5), and -75 ~ -90 kPa (T6). Different water potential treatments had a significant effect on plant growth and metal uptake efficiency. Compared to T3, T2 was more effective in promoting plant growth and development, with an increase in biomass of 23% and 17% in both fresh weight (FW) and dry weight (DW), respectively. T2 and T3 had the highest cadmium (Cd) content in the shoot (280.2 mg/kg) and (283.3 mg/kg), respectively, whereas T1 had the lowest values (204.7 mg/kg). Cd availability for plants in the soil was affected by moving soil moisture cycles. Changes in soil moisture that were either too high or too low compared to the ideal soil water content for S. alfredii growth resulted in a significant reduction in Cd accumulation in shoots. Tryptophan, phenylalanine, and other amino acids were accumulated in T5, whereas only tryptophan and phenylalanine slightly increased in T1. Sugars and alcohols such as sucrose, trehalose, mannitol, galactinol, and mannobiose increased in T5, while they decreased significantly in T1. Interestingly, in contrast to T1, the two impaired metabolic pathways in T5 (galactose and starch metabolism) were identified to be glucose metabolic pathways. These findings provide scientific information (based on experiments) to improve biomass production and metal uptake efficiency in hyperaccumulating ecotype of S. alfredii for phytoremediation-contaminated agricultural fields.

Role of cationic surfactants in palladium adsorption of commercial ion exchange resins using electroless plating solutions

AbstractThis work investigates the role of cationic surfactants in the adsorption of palladium ions from synthetic electroless plating solutions using a commercial resin, Lewatit TP-214. This would also help us in determining the batch adsorption experiments elaborated on the optimal parameters such as surfactant concentration, pH, dosage, initial metal ion concentration for the development of an ion-exchange resin with high metal removal efficiency. Critical micelle concentration (CMC) appears to be an important parameter in determining the adsorption behavior of ion-exchange resins with palladium ions. Equilibrium models were measured for their fitness with the obtained Pd (II) batch adsorption characteristics and Freundlich isotherm confirms the heterogeneous Pd (II) adsorption on Lewatit TP-214. FTIR analysis confirmed that the Pd (II) metal uptake of Lewatit TP-214 resin largely depends on amine groups (-NH2+ and -NH+) and the donor atoms attached to cationic surfactant. The optimized choice of adsorption parameters (pH of 8, dosage of 1 g/L, and contact time of 300 min) of Lewatit TP-214 adsorbent provided the highest metal uptake and removal efficiency as 201.7 mg/g and 90.16%, respectively, for the lowest Pd concentration of 300 mg/L.

Phytohormones enhance heavy metal responses in Euglena gracilis: Evidence from uptake of Ni, Pb and Cd and linkages to hormonomic and metabolomic dynamics

Over the last decade, significant effort has been made to understand phytohormonal functions (e.g., cytokinins (CKs) and abscisic acid (ABA)) in metal stress responses of higher plants and algae. Despite the potential for these phytohormones to improve industrial remediation by Euglena gracilis (Euglenophyceae), no such roles have been elucidated for this highly adaptive species and its response to heavy metals. This study demonstrates that toxic metals (nickel, lead, cadmium) modify hormonal activity profiles (i.e., CK forms and their concentrations) in E. gracilis. Furthermore, exogenous ABA or CK (tZ) enabled higher metal uptake efficiency (i.e., 9.35% in lead and 9.2% in cadmium uptake with CK) and alleviated metal toxicity through the regulation of endogenous CKs (i.e., total CK, isoprenoid CK) and gibberellin (GAs, GA1 and GA3) levels. These responses suggest that E. gracilis regulates multiple phytohormone signals during metal stress acclimation. A deeper approach, using untargeted metabolomic analyses, gave more detailed insight into phytohormone-controlled pathways and associated modified metabolites, which were frequently related to metal accumulation and the physiological acclimation to metal presence. Significant changes in the levels of cellular metabolites, especially those involved in acclimation to metal stress, were under the influence of phytohormones in algal cells. When grown under metal stress conditions, the presence of exogenous ABA or CKs, caused changes in cellular metabolites which included those from: lipid pathways, riboflavin metabolism, the biosynthesis of cofactors/vitamins, and carbohydrate metabolism. Also, bioactive secondary metabolites (e.g., terpenoids, alkaloids, flavonoids, carotenoids) were modified in algal cells treated with phytohormones. Thus, the study gives a detailed view on the regulatory functions of ABA and CKs in algal metal bioremediation strategies, which are attributed to enhanced metal uptake and in the fine-tuning of plant hormone levels during metal stress response. The results can guide efforts to develop efficient, low-cost and environmentally friendly methods for bioremediation.

Species- and Metal-Specific Responses of the Ionome of Three Duckweed Species under Chromate and Nickel Treatments

In this study, growth and ionomic responses of three duckweed species were analyzed, namely Lemna minor, Landoltia punctata, and Spirodela polyrhiza, were exposed for short-term periods to hexavalent chromium or nickel under laboratory conditions. It was found that different duckweed species had distinct ionomic patterns that can change considerably due to metal treatments. The results also show that, because of the stress-induced increase in leaf mass-to-area ratio, the studied species showed different order of metal uptake efficiency if plant area was used as unit of reference instead of the traditional dry weight-based approach. Furthermore, this study revealed that μXRF is applicable in mapping elemental distributions in duckweed fronds. By using this method, we found that within-frond and within-colony compartmentation of metallic ions were strongly metal- and in part species-specific. Analysis of duckweed ionomics is a valuable approach in exploring factors that affect bioaccumulation of trace pollutants by these plants. Apart from remediating industrial effluents, this aspect will gain relevance in food and feed safety when duckweed biomass is produced for nutritional purposes.

Metal uptake efficacy and phytoremediation potential of plants grown around soil dumpsites in Anyigba, Kogi State, Nigeria

Plant’s accumulation and translocation potentials were investigated for phytoremediation purposes, recovery of metals, potential for edibles/vegetables to cause harm to humans. Plant and soil were collected, prepared, digested in mixturesof H2O2-HNO3 and Li2B4O7-LiBO2 for plants and soils respectively. The concentrations of Co, Cd, Cr, and As, accumulation and translocation were determined. Data were evaluated using bioconcentration (BCF), translocation factor (TF), bioaccumulation coefficient (BAC), metal uptake efficiency (ME%), multivariate analyses to establish hyperaccumulators, phytoextractors, phytostabilizers, source of metals and theirtoxicity. Analysis of variance (ANOVA) showed data were significant at p <0.05. Correlation,factor and cluster analyses were employed to understand the accumulation and translocation of metals in soils and plants tissues.From this study, Colocasia asculenta, Corchorus aestuans and Laportea aestuans were hyperaccumulators of Co. Arsenic had only phytostabilizers. COA and LA were phytostabilizers and Sida acuta was phytoextractorof Cd respectively. Chromium, Co and Cd could be phytomined from some of the plants. Vegetables/edibles values in shoots and leaves were above permissible levels for Cr, Co and Cd. Only Sida acuta was not edible.Metal uptake efficacy (%) order were Co (28.99 to 89.08) > Cd (21.74 to 50.96) >Cr (22.90 to 49.06) > and As (9.65 to 39.19).

Assessment of rhizosphere bacterial diversity and composition in a metal hyperaccumulator (Boehmeria nivea) and a nonaccumulator (Artemisia annua) in an antimony mine.

Heavy metal hyperaccumulators are widely used in mining restoration due to their ability to accumulate and transport heavy metals, compared to nonaccumulators. Rhizosphere bacteria in metal hyperaccumulators play a key role in the uptake of heavy metals from soil; however, assessments of the differences of rhizosphere bacteria between metal hyperaccumulators and nonaccumulator are scarce. To understand the difference of bacterial composition between hyperaccumulator and nonaccumulator in rhizosphere, the diversity and composition of rhizosphere bacteria in a metal hyperaccumulator (Boehmeria nivea) and a nonaccumulator (Artemisia annua) grown in the same field in Xikuangshan were evaluated using Illumina Miseq high-throughput sequencing technology. Boehmeria nivea and A. annua had 3926 overlapping OTUs, 19,736 and 17,579 unique OTUs, respectively. Boehmeria nivea had lower Chao1 index, Shannon index and Pielou index than A. annua. The dominant phyla and genera of rhizosphere bacteria in B. nivea and A. annua were similar, but some rhizosphere bacterial communities with heavy metal remediation ability mainly appeared in the rhizosphere of the hyperaccumulator. Compared to A. annua, B. nivea showed a significantly higher relative abundance of rhizosphere bacteria, such as Acidobacteria and Bacteroidete at the phylum level and RB41 at the genus level. Some specific rhizosphere bacteria with the ability to bind metal, such as Leifsonia and Kibdelosporangium, were only found in the rhizosphere of B. nivea. Results indicated that B. nivea, as a metal hyperaccumulator, has a key function in governing metal-resistant rhizosphere bacteria in response to antimony compound pollution stress. Understanding the diversity of rhizosphere bacteria between hyperaccumulators and nonaccumulators is beneficial to formulate strategies to improve metal uptake efficiency by selecting specific plant species and rhizosphere bacteria grown on polluted soil.

Rhizobium rhizogenes-mediated root proliferation in Cd/Zn hyperaccumulator Sedum alfredii and its effects on plant growth promotion, root exudates and metal uptake efficiency

In this study, Rhizobium rhizogenes-mediated root proliferation system in Sedum alfredii has been established. Twenty strains of R. rhizogenes were screened for root proliferation. A significant difference (P < 0.01) was observed in plant morphological characters under influence of different bacterial strains. The highest root fresh weight (3.236 g/plant) was observed with strain AS12556. Furthermore, significant difference (P < 0.05) was observed in the chemical composition of organic acids, Tartaric acid (TA), Succinic acid (SA), Malic acid (MA), Citric acid (CA) and Oxalic acid (OA), pH, Total Nitrogen (TN), Total Organic Carbon (TOC) and soluble sugars in root exudates with different R. rhizogenes mediated roots. Furthermore, a series of hydroponics experiments were conducted with varying concentrations of Cd (25, 50 and 75 µM) and Zn (100, 200 and 500 µM) to assess the phytoextraction efficiency of proliferated roots with Rhizobium. Several plants with proliferated roots showed enhanced growth and improved metal extraction efficiency. Five strains (LBA 9402, K599, AS12556, MSU440 and C58C1) were identified as potential strains for root proliferation in Sedum alfredii. R. rhizogenes strain AS12556 improved Cd/Zn phytoextraction by exogenous production of phytochemicals to promote root proliferation, improved shoot biomass, lowered oxidative damage and enhanced phytoextraction efficiency in S. alfredii. Therefore, it has been selected as a potential microbial partner of S. alfredii to develop extensive rooting system for better growth and enhanced phytoremediation potential. Results suggest that R. rhizogenes mediated root proliferation system can be used for optimizing metal extraction from contaminated soils.

Phytoremediation of soil treated with metalliferous leachate from an abandoned industrial site by Alternanthera sessilis and Ipomoea aquatica: Metal extraction and biochemical responses

Metalliferous soil (MS) was collected from near an abandoned pulp and paper mill, and leachates were extracted in water to simulate natural water percolation. Metalliferous soil leachates (MSL) were added to the garden soil, and phytoremediation trials were carried out by Alternanthera sessilis and Ipomoea aquatica for 28-d in pot experiments. The aqueous leachates could extract 18–33% of the metals from the MS. The maximum accumulation of 38–43 μg Cd/g, 211–294 μg Pb/g, 199–218 μg Cr/g, 92–95 μg Ni/g, 422–511 μg Cu/g, 2366–3531 μg Zn/g, 6910–6105 μg Fe/g, and 4410–5576 μg Mn/g in the plants exceeded the respective toxic ranges, indicating their tolerance. Plants showed >50% removal efficiency for Pb, Cr, and Cu. For other metals, variable removal efficiency between 25 and 48% was also noted. The root morphology and X-ray microanalysis revealed Pb, Cr, and Fe deposits that influenced their uptake and possible interactions with other elements. The treated plants showed reduced chlorophylls, carotenoids, protein, and ascorbate, along with an increase in superoxide radical, hydrogen peroxide, and lipid peroxidation. A concomitant increase in the activities of all the vital antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidise, and guaiacol peroxidise helped to combat multi-metal stress in them. Overall, owing to their metal uptake efficiency, significant oxidative stress mitigation properties, rapid growth rate, and large biomass, A. sessilis, and I. aquatica can be recommended for use in the decontamination of multiple metals.

The cup plant (Silphium perfoliatum L.) – a viable solution for bioremediating soils polluted with heavy metals

Heavy metal pollution, manifested by the accumulation, toxicity and persistence in soil, water, air, and living organisms, is a major environmental problem that requires energetic resolution. Mining tailing areas contain metal minerals such as Cu, Zn, Pb, Cr and Cd in high concentrations that pollute the environment and pose threats to human health. Phytoremediation represents a sustainable, long-term, and relatively inexpensive strategy, thus proving to be convenient for stabilizing and improving the environment in former heavy metal-polluted mining sites. This study presents the bioremediation potential of Silphium perfoliatum L. plants, in the vegetative stages of leaf rosette formation, grown on soil polluted with heavy metals from mining dumps in Moldova-Noua, in the Western part of Romania. The bioaccumulation factor (BAF), translocation factor (TF), metal uptake (MU) and removal efficiency (RE) of Cu, Zn, Cr and Pb by S. perfoliatum plants were determined in a potted experiment in controlled environmental conditions. The reference quantities of heavy metals have been determined in the studied soil sample. The experiment followed the dynamics of the translocation and accumulation of heavy metals in the soil, in the various organs of the silphium plants, during the formation of the leaf rosette (13-18 BBCH). The determination of the amount of heavy metals in soil and plants was achieved by the method of digestion with hydrochloric and nitric acid 3/1 (v/v) quantified by atomic absorption spectroscopy (AAS). The obtained experimental results demonstrate that the substrate has a high heavy metal content being at the alert threshold for Zn (260.01 mg kg-1 in substrate compared with alert threshold 300 mg kg-1) and at intervention thresholds for other metals (Cu -234.66 mg kg-1/200 mg kg-1; 299.08 mg kg-1/300 mg kg-1 and Pb-175.18 mg kg-1/100 mg kg-1). The average concentration of the metals determined in dynamics in the dry biomass of plants varied between roots, petioles, and laminas. The root is the main accumulator for Cu and Cr (Cu – 37.32 mg kg-1 -13 BBCH to 43.89 mg kg-1-15 BBCH and 80.71 mg kg-1 – 18 BBCH; Cr – 57.43 mg kg-1 – 13 BBCH to 93.36 mg kg-1 -18 BBCH), and for Zn and Pb the lamina seems to carry the same function. Preliminary results show that Silphium perfoliatum may be a viable alternative in the bioremediation and treatment of heavy metal-contaminated area.

Properties and Potential Applications of Carboxymethyl-kappa-carrageenan Hydrogels Crosslinked by Gamma Radiation

Carboxymethyl κ-carrageenan (CMKC), with different degrees of substitution (DSs), were gamma-irradiated in viscous or paste solutions. Successfully synthezised chemically crosslinked hydrogels showed dependence on the DS, concentration, and radiation dose. The highest gel fraction was 76% exhibited by CMkC-3s hydrogel with a DS of 1.58. The hydrogels showed different swelling degrees in water and saline. Swelling behavior vs. time, in both solvents, corresponded to 2nd-order kinetics. The CMkC-3s at 20% concentration irradiated at 15 kGy had the highest water absorption of 334 g water/g dry gel. Selected hydrogels were evaluated for applications as wound dressing, as water retainer in sandy soil, and as metal adsorbent. As a wound dressing, CMkC-2s and CMkC-3s hydrogels exhibited considerable tensile strengths, abilities to absorb pseudo extracellular fluid, and extractables with pH/conductivity conducive for healing promotion. Also, the CMkC-3s hydrogel had no cytotoxic potential based on the MTT test. As water retainer in sandy soil, test samples with 0.1, 0.3, and 0.5% CMkC-3s granules initially retained 25.1%, 32.2%, and 42.6% water, respectively, compared to 19.2% of the sandy soil alone. On Day 7, the three sandy soil-CMkC groups still had 13.7–29.3% water, while the control had only 3.85%. In the batch adsorption studies, the hydrogels adsorbed Cu2+, Zn2+, Cd2+, and Pb2+ heavy metals in the solution at different capacities, with Cd2+ as the highly adsorbed and Pb2+ as the least. The CMkC-3s hydrogel showed the highest metal uptake and adsorption efficiency, followed by CMkC-2s, then CMkC-1s. The CMkC-3s hydrogel, further tested on pH effect, exhibited optimum metal uptake at neutral pH.

Utilization of Leptolyngbya boryana mat for modulating nutrient uptake and its translocation in rice (Oryza sativa)

The effect of algalization on paddy yield and its nutrition were analyzed. The application of Leptolyngbya boryana mat in conjunction with different doses of fertilizer (R + A + 75%N, R + A + 100%N, R + 100%N, and R + A + 125%N) was performed in the paddy fields of Andhra Pradesh, India. Leptolyngbya boryana mat acted as a promising metal sequester and demonstrated an elicited photosynthetic activity (2-fold increase in Chl-a), carbohydrate (2-fold increase) and lipid (1.7-fold increase) content (% w/w) after 2-month cultivation. It also displayed proficient metal (ppm) uptake efficiency in the order Ca > Fe > Mg > K > Na > Mn > Zn > Cr. In grains, higher nutrient accumulation for Fe (~2-fold), Mg (~1.5-fold) and Ca (~5-fold), and a significantly higher translocation factor (Tf) in the order Ca > K > Mg were recorded under R + A + 125%N. In essence, algalization substantially improved the overall nutritive quality of the rice grains, especially its iron content.

Effects of sophorolipids augmentation on the plant growth and phytoremediation of heavy metal contaminated soil

Heavy metal toxicity to plants and low metal bioavailability in soil decreases the efficiency of phytoremediation. Thus, the present study evaluates the effects of sophorolipids (SL) amendment in heavy metal contaminated soil on the growth of Medicago sativa and Bidens pilosa, and metal uptake efficiency and response towards metal stress in B. pilosa. Results showed that root and shoot lengths of SL augmented plants were found to be higher in comparison to untreated plants. The increase in plant heights was 17% and 11% for M. sativa and B. pilosa, respectively after 60 d of experiment. In another experiment (40 d), presence of Cd in soil (29.2 mg kg−1) negatively affected the phytobiomass of B. pilosa. However, SL augmentation restored the phytobiomass by reducing the toxic effects of Cd on B. pilosa. The dry weights of B. pilosa were 445, 285, and 456 mg plant−1 in control, Cd contaminated soil and Cd and SL treated soil, respectively. SL augmentation decreased the proline concentration in B.pilosa. The observed proline concentration were 18.2 and 40.2 μmoles proline g−1 in SL treated soil and without SL treatment, respectively. Soil urease activity in SL augmented experiment (1.89 μg g−1 h−1) was significantly (p < 0.05) higher than the Cd contaminated (5.7 times) and control (1.5 times) experiments. The Cd accumulation in B. pilosa was also highest in SL augmented soil. The study indicates that SL augmentation is a viable option to induce phytoremediation as it increases Cd accumulation and plant growth, improves the soil microbial activity and reduces metal stress in B. pilosa.

A study of a newly synthesized ligand and its metal complexes in bulk and nano size and metal uptake efficiency

A newly synthesized ligand derived from 2‐amino thiophenol and benzoic anhydride and its Co(II), Cd(II), La(III) (in bulk and nano size), and Gd(III) complexes was investigated and characterized. The maximum elimination capacity of the newly synthesized ligand was investigated towards the removal of Co(II), Cd(II), La(III), and Gd(III) ions from aqueous solutions. It was found that the ligand has the best removal ability for Cd(II) metal of 98.66% at a concentration of 0.03 mg/L.

Heavy metal removal from water by adsorption using a low-cost geopolymer.

In the present study, a geopolymer from dolochar ash was synthesized and used for the removal of heavy metal ions such as Co(II), Ni(II), Cd(II), and Pb(II) from the aqueous solution through the adsorption process. The geopolymer was characterized by a series of analytical techniques. The XRD pattern revealed the loss of dolochar ash crystallinity on geoploymerization. The peak at 982cm-1 observed in the FTIR spectrum due to Si-O-Si and Si-O-Al bonds confirmed the formation of geopolymer. BET surface area analyses indicated the mesoporous nature of the sample. The adsorption experiments revealed the higher removal efficiency of the geopolymer in comparison with the feed dolochar ash. The effects of different experimental factors such as pH, temperature, reaction time, and initial concentration of metal ions on metal uptake efficiency were evaluated to optimize the removal efficiency. The maximum removal of 98-99% was achieved when the pH, temperature, and initial metal ion concentration were 7.8, 343K, and 10ppm, respectively. The adsorption process followed the pseudo-second-order rate equation and validated the Langmuir adsorption model. Thermodynamic parameters such as ΔH, ΔS, and ΔG confirmed that the process to be spontaneous and endothermic. This geopolymer was found to compete efficiently with many adsorbents reported in the literature for water treatment.

The counter defence system of antioxidants in Coelomycetous emerging human and plant pathogenic fungus Macrophomina phaseolina against copper toxicity.

Macrophomina phaseolina (Tassi) Goid. is primarily a phytopathogen but also exhibits potential to cause infection in human being due to its aggressive and robust nature. Adaptation potential in M. phaseolina was assessed after exposing to heavy metal copper through analysing macro- and microscopic as well as physiological attributes. Considerable modifications were observed in morphology with an increase in concentrations (25, 75, and 100ppm) of copper as compared with control. Total content of protein and activities of the antioxidant enzymes were affected differently at different copper concentrations. The fungal biomass, metal accumulation, metal uptake efficiency, and bioaccumulation factors were decreased due to the increase in copper concentrations. Fourier transformed infrared spectroscopic assessment showed hydroxyl, carboxyl, and amine groups as major metal accumulation sites. It is concluded that Cu-based fungicides can manage this pathogen but excessive application may accumulate in the plant that will transfer along the food chain, reaching ultimately the human body.

Phytoremediation of cadmium (Cd) and uranium (U) contaminated soils by Brassica juncea L. enhanced with exogenous application of plant growth regulators.

This investigation was made to examine the role of indole-3-acetic acid (IAA), gibberellin A3 (GA3), 6-Benzylaminopurine (6-BA), and 24-epibrassinolide (EBL) in improving stress tolerance and phytoremediation of the cadmium (Cd) and uranium (U) by mustard (Brassica juncea L.). The optimum concentrations of IAA, GA3, 6-BA, and EBL were determined based on plant biomass production, metal uptake, translocation, and removal efficiency. The biomass and total chlorophyll content decreased under Cd and U stress. Nevertheless, the application of IAA, GA3, and 6-BA significantly (p < 0.05) increased the growth and total chlorophyll content of mustard. The malondialdehyde (MDA) and H2O2 content of mustard were enhanced under Cd and U stress, but they were significantly (p < 0.05) decreased in plant growth regulators (PGRs) treatments (except for EBL). PGRs treatments increased activities of antioxidant enzymes such as superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase, thus reducing the oxidative stress. Furthermore, the shoot uptake of Cd and U of IAA and EBL treatments was significantly (p < 0.05) higher than that of other treatments. IAA and EBL also have more significant effects on the translocation and remediation of Cd and U compared to GA3 and 6-BA. The removal efficiency of Cd and U reached the maximum in the 500 mg L-1 IAA treatment, which was 330.77% and 118.61% greater than that in the control (CK), respectively. These results suggested that PGRs could improve the stress tolerance and efficiency of phytoremediation using B.juncea in Cd- and U- contaminated soils.

Mycoremediation of heavy metal (Cd and Cr)-polluted soil through indigenous metallotolerant fungal isolates.

Remediation of heavy metals, other than microbial bioleaching method, is expensive and unsuitable for large contaminated areas. The current study was aimed to isolate, identify, and test the potential of indigenous fungal strains for heavy metal removal from contaminated soil. A total of three metallotolerant fungal strains, i.e., Aspergillus niger (M1DGR), Aspergillus fumigatus (M3Ai), and Penicillium rubens (M2Aii), were isolated and identified by phenotyping and genotypingfrom heavy metal-contaminated soil of Hattar Industrial Estate, Pakistan. A. niger was found to be the most successful strain for the removal of heavy metals from the contaminated soil with maximum bioaccumulation efficiency of 98% (Cd) and 43% (Cr). In contrast, A. fumigatus showed comparatively low but still considerable bioleaching potential, i.e., 79% and 69% for Cd and Cr removal, respectively. Maximum metal uptake efficiency, i.e., 0.580mgg-1 and 0.152mgg-1 by A. niger strain was noticed for Cd and Cr with Czapek yeast extract (CYE) and Sabouraud dextrose broth (SDB) media, respectively. A. fumigatus (M3Ai) exhibited the maximum bioleaching capacity (0.40mgg-1) for Cr with CYE medium. The results reveal that A. niger M1DGR and A. fumigatus M3Ai could be used to develop new strategies to remediate soil contaminated with heavy metals (Cd and Cr) through either in situ or ex situ mycoremediation.