Remediation Mechanisms Research Articles

Microbial remediation of heavy metal-polluted water

Heavy metal pollution in water has become a global environmental problem, threatening aquatic ecosystems and human health. Physical and chemical methods can effectively remove heavy metal pollutants, while their applications are limited due to the high costs, complex operation, and susceptibility to secondary pollution. Bioremediation is the most promising method for eliminating toxic pollutants. Microorganisms including bacteria, fungi, and algae can convert toxic heavy metals into less toxic forms, which has become an effective and environmentally friendly solution for the remediation of heavy metal pollution in water environments. This paper expounds the toxicity and mechanism of heavy metal pollution, microbial remediation mechanisms, and primary microbial remediation strategies, providing a reference for the removal or reduction of metal pollutants in water environments as well as the development of related technologies.

Effects of Acid Modified Mineral Materials on Soil Cadmium Pollution and Plant Remediation

In response to the problem of soil heavy metal pollution, acid modified mineral materials were used to study the changes in adsorption performance, surface charge, and other indicators of four clay mineral materials, vermiculite, arsenic sandstone, shale, and zeolite, under acid modified conditions. The changes in soil physicochemical properties, heavy metal content, and plant growth before and after remediation were analyzed. The study showed that the introduction of acid modified adsorption materials increased the specific surface area and cation exchange capacity, enhanced adsorption performance, and provided theoretical reference for the mechanism and effect of remediation of cadmium contaminated soil. To optimize the application amount of remediation materials and develop cheap, effective, and scalable heavy metal remediation materials, it has important practical significance. Bangladesh J. Bot. 53(3): 803-809, 2024 (September) Special

APMCG-1 attenuates ischemic stroke injury by reducing oxidative stress and apoptosis and promoting angiogenesis via activating PI3K/AKT pathway

Ischemic stroke (IS) is a major cause of mortality and morbidity worldwide. Beyond thrombolysis, strategies targeting anti-oxidative apoptosis and angiogenesis are considered prospective therapeutic strategies. Nevertheless, existing natural and clinical remedies have limited efficacy in the management of IS. Moreover, despite their millennial legacy of IS remediation, natural remedies such as ginseng incur high production costs. The novel glycopeptide APMCG-1, extracted from mountain-cultivated ginseng dregs in our previous study, is a potent therapeutic candidate for IS. This study investigated APMCG-1's remedial mechanisms against IS injury using an H2O2-induced oxidative stress paradigm in human umbilical vein endothelial cells (HUVECs) emulating ischemic endothelial cells, in a ponatinib-induced zebrafish IS model, and in rat middle cerebral artery occlusion (MCAO) prototypes. Cellular assays confirmed the proficiency of APMCG-1 in preventing oxidative stress and cell death, fostering regeneration, and facilitating neovascularization within the H2O2-stressed HUVECs framework. Moreover, APMCG-1 augmented hemodynamic velocity, oxidative stress mitigation, apoptosis reduction, and motor enhancement in a zebrafish model of IS. In MCAO rats, APMCG-1 ameliorated neurological deficits and cerebral injury, as evidenced by increased neurological scores and diminished infarct dimensions. In cells and animal models, APMCG-1 activated the PI3K/AKT signaling pathway, modulating factors such as Nrf2, Bcl-2, Caspase 3, eNOS, and VEGFA, thereby ameliorating cellular oxidative distress and catalyzing angiogenesis. Collectively, these results demonstrate the potential protective effects of APMCG-1 in IS pharmacotherapy and its prospective utility as an herbal-derived IS treatment modality.

Mechanism of remediation of U(VI) contaminated simulated soil by AC‐nHAP gel microsphere as PRB combined electrokinetic technology

Mechanism of remediation of U(VI) contaminated simulated soil by AC‐nHAP gel microsphere as PRB combined electrokinetic technology

Remediation of heavy metal contaminated soil in mining areas with vaterite-type biological calcium carbonate

In recent years, research on the remediation of heavy metal contaminated soil by microbially induced carbonate precipitation (MICP) technology has yielded significant findings. However, when utilizing MICP for remediation in situ, urea and calcium chloride may produce high concentrations of NH4+ and Cl-, which subsequently cause secondary pollution. If the biological calcium carbonate (Bio-CaCO3) produced by MICP is employed as a highly efficacious adsorbent, secondary pollution can be avoided while remediating heavy metal pollution. In this study, vaterite-type Bio-CaCO3 was prepared under the regulation of sophorolipids, and the remediation effect and mechanisms for heavy metal contaminated soil were investigated. The results demonstrated that sophorolipids facilitate the formation and stabilization of vaterite-type Bio-CaCO3. The addition of vaterite-type Bio-CaCO3 could notably increase the content of soil organic matter, enhance soil urease activity, and reduce soil catalase activity. On the 30th day of remediation with vaterite-type Bio-CaCO3, the active state content of Pb and Cd in the soil exhibited a decrease of 41.23% and 35.00%, respectively. Additionally, the exchangeable state content demonstrated a reduction of 6.61% and 8.48%, while the carbonate-bound state exhibited an increase of 12.05% and 13.89%, respectively. The principal mechanisms for the remediation of heavy metal contaminated soil by vaterite-type Bio-CaCO3 may be attributed to ion exchange, chemical precipitation, physical adsorption, and complexation reactions. The analysis of the microbial community structure demonstrated that vaterite-type Bio-CaCO3 could enhance the abundance of multiple genera with urease-producing genes, including Pseudomonas, Staphylococcus, and Bacillus while maintaining the soil biodiversity. This study provides a new idea for the remediation of heavy metal contaminated soil around the mining area and offers technical support for the construction of green mines.

Mangrove fungi in action: Novel bioremediation strategy for high-chloride wastewater

Bioremediation of extremely high-chloride wastewater poses significant challenges due to the adverse effects of elevated salt concentrations on most microorganisms, where chloride levels can be as high as 7% (w/v). Mangrove wetlands derived fungus, Aspergillus aculeatus, emerged as a promising candidate, capable of removing approximately 40% of chloride ions in environments with concentration of 15% (w/v), representative of industrial wastewater conditions. Transcriptomics and biochemical assays conducted under increasing salt conditions revealed that elevated chloride concentrations induce the expression and activity of S-adenosyl methionine-dependent methyltransferase, which facilitates the conversion of chloride into chloromethane. This is the first report characterizing the biological mechanism behind high salt tolerance and chloride removal capacity of Aspergillus aculeatus. This salt remediation mechanism may work as a starter for developing future bioremediation strategies to treat high-chloride wastewater using fungi, offering an eco-friendly alternative to traditional physical or chemical methods.

Research Progress in the Joint Remediation of Plants–Microbes–Soil for Heavy Metal-Contaminated Soil in Mining Areas: A Review

Plants growing in heavy metal (HM)-contaminated soil have evolved a special detoxification mechanism. The rhizosphere gathers many living substances and their secretions at the center of plant roots, which has a unique ecological remediation effect. It is of great significance to thoroughly understand the ecological process of rhizosphere pollution under heavy metals (HMs) stress and develop biotechnology for joint remediation using plants and their coexisting microbial systems according to the mechanism of rhizosphere stress. Microbes can weaken the toxicity of HM pollutants by transforming the existing forms or reducing the bioavailability in the rhizosphere. Microbes survive in the HM-polluted soils through the production of stress-resistant substances, the participation of proteins, and the expression of heavy metal resistance genes, which strengthens the resistance of plants. Moreover, microbes can improve the nutritional status of plants to improve plant resistance to HMs. Plants, in turn, provide a habitat for microbes to survive and reproduce, which greatly accelerates the process of bioremediation. Briefly, the combined remediation of soil HMs pollution by plants and microbes is a promising, green, and sustainable strategy. Here, we mainly elucidate the joint remediation mechanism of plant–microbe symbiosis and introduce the coping characteristics of plants, microbes, and their symbiotic system, hoping to provide a scientific basis for the remediation of HM-contaminated soil in mining areas and the sustainable development of the ecological environment.

Remediation Mechanism and Evaluation for Cd Polluted Vegetable Soil using Palygorskite

Remediation Mechanism and Evaluation for Cd Polluted Vegetable Soil using Palygorskite

Making Systemic Risk Assessments Work: How the DSA Creates a Virtuous Loop to Address the Societal Harms of Content Moderation

Abstract The European Union’s Digital Services Act (DSA) introduces a new regulatory approach to address the societal harms of online platforms: Systemic risk assessments. While a core component of the DSA, the regulation only outlines the standards and processes governing systemic risk assessments in broad strokes. It remains unclear what these systemic risk assesments will entail in practice. This Article develops a proposal of how systemic risk assessments should be implemented. It situates systemic risk assessments as a critical step toward platform accountability as they address societal harms, while existing approaches, such as remedy mechanisms, only protect user rights. Engaging with intangible harms and regulating speech and public discourse, risk assessments also entail significant challenges. Conventional reference points for content moderation regulation, such as terms and conditions, contractual freedom, fundamental rights and expertise, do not provide practical and legitimate bases to concretize risk assessment obligations. Public actors, such as the European Commission, should refrain from defining substantive standards, too, as they are directly bound by freedom of expression guarantees. Instead, the Article argues, the Commission should foster a procedural framework, a “virtuous loop,” which empowers civil society and allows it to specify and refine the standards governing systemic risks over time. Developing this framework, the Article explains how systemic risk assessment can fix “multistakeholderism,” and “multistakeholderism,” in turn, can help make systemic risk assessments work.

Date palm: a potential nutraceutical and phytomedicine in most frequent aging associated diseases

AbstractSenescence, often known as ageing, is a condition of decline that shows itself as a decrease in fertility and survival at older ages. Ageing theory suggests that ageing evolves as a function of life history optimization or because of mutation pressure, depending on the degree of externally imposed mortality and shocks to fertility. An important key factor to many aging-related disorders (ARDs), such as hypertension, myocardial infarction, atherosclerosis, osteoporosis, cancer, and neurodegenerative diseases like Alzheimer’s and Parkinson’s disease, is ageing, a process influenced by countless biological and genetic pathways. While there have been significant advancements in therapeutics for age-related disorders, nutritional therapy, encasing various products from natural sources is recommended for durable and fruitful treatment. Numerous health advantages of the date palm, Phoenix dactylifera, have been well-documented. These include antioxidant, anti-inflammatory, cardioprotective, and neuroprotective activity. Phytochemical analysis of date palm demonstrates a lot of beneficial nutraceuticals that can ameliorate ARDs like polyphenols, phytosterols, carotenoids, flavonoids, terpenoids, fatty acids, carbohydrates, vitamins, and amino acids etc. The major signaling and molecular pathways by which these phytoconstituents exert their anti-ageing effects include terminating inflammation by blocking the release in of IL-6, TNF-α and clearance of Aβ plaques for neurodegenerative diseases; blocking ACE-II and HMG-CoA for cardio-protection; regulating RANK, p38MAPK-Runx2 pathways, and insulin-growth factor-1 (IGF-1) for osteoporosis. However, research on the benefits of date palm is still lacking. The purpose of this review is to shed light on the various biological activities of date palm in ARDs and to explore its remedial mechanisms.

Floatable expanded perlite-loaded Z-scheme n-C3N5/Ag2CO3 core-shell structure with C-defects for enhanced adsorption and photodegradation of microcystin-LR: Insights into performance and mechanism

Efficient in-situ treatment of high concentrations microcystin-LR in surface waters is especially challenging. Herein, spherical floatable Z-scheme core-shell photocatalyst EP@n-C3N5/Ag2CO3 (EP@CNAC) with carbon defects was constructed using expanded perlite (EP) as floating carrier for efficient adsorption and degradation of microcystin-LR. The carbon defect sites and electron density distribution of C3N5 were investigated by DFT calculation. Benefited from synergistic effects of morphology and defect engineering, Z-scheme heterojunction, and floatability, the carrier migration kinetics and solar spectral responsiveness of EP@CNAC-3 were significantly enhanced, and 97 % of microcystin-LR was degraded within 16 min. The LC-MS, Fukui index, and electrostatic potential of microcystin-LR revealed that Adda side chain was cleaved by electrophilic attack of 1O2, while ring-opening reaction and decarboxylation were caused by nucleophilic attack of •O2- and strong oxidative properties of h+, respectively. These findings are expected to bring new insights into design of innovative floating photocatalysts and in-situ remediation mechanism of microcystin-LR.

Remediation Mechanism of Chitosan-modified Biochar on Cd-contaminated Farmland Soil and Its Effect on Bacterial Community

To explore the remediation mechanism of chitosan-modified biochar （passivator） on Cd-contaminated farmland soil, pot experiments were conducted to determine the effects of passivator on soil physical and chemical properties, ryegrass biomass, enzyme activity, and the response of soil bacterial diversity and structure. The results showed that when the amount of passivating agent was increased from 0.5% to 3%, the content of available Cd in soil was significantly decreased compared with that in the control, and the above-ground and subsurface biomass of ryegrass was increased by 1.08-1.56 times and 1.00-1.68 times, respectively. The enrichment and running coefficients were reduced by 6.15%-30.00% and 10.42%-31.25%, respectively. The correlation analysis results showed that soil pH, CEC, SOM, AN, AP, and AK were significantly negatively correlated with DTPA-Cd, indicating that the application of a passivating agent promoted the passivation of Cd in soil by changing the physical and chemical properties of soil. High-throughput sequencing results showed that the application of the inactivation agent changed the structure and diversity of the soil bacterial community, which was manifested as a significant decrease in α diversity, significant isolation of bacteria between different treatment groups, and an increase in the relative abundance of beneficial bacteria such as Sphingomonas and Blastococcus. Moreover, the activities of soil urease and cellulase increased, whereas the activities of sucrase and catalase decreased with the addition of a passivator. This study provides a theoretical basis and technical reference for the application of modified biochar in the remediation of Cd-contaminated farmland soil.

Huangqi Guizhi Wuwu Decoction Improves Inflammatory Factor Levels in Chemotherapy-induced Peripheral Neuropathy by Regulating the Arachidonic Acid Metabolic Pathway.

Chemotherapy-induced Peripheral Neuropathy (CIPN) is a common complication that arises from the use of anticancer drugs. Huangqi Guizhi Wuwu Decoction (HGWWD) is an effective classic prescription for treating CIPN; however, the mechanism of the activity is not entirely understood. This study aimed to investigate the remedial effects and mechanisms of HGWWD on CIPN. Changes in behavioral, biochemical, histopathological, and biomarker indices were used to evaluate the efficacy of HGWWD treatment. Ultra-high-performance liquid chromatography/mass spectrometry combined with the pattern recognition method was used to screen biomarkers and metabolic pathways related to CIPN. The results of pathway analyses were verified by protein blotting experiments. A total of 29 potential biomarkers were identified and 13 metabolic pathways were found to be involved in CIPN. In addition HGWWD reversed the levels of 19 biomarkers. Prostaglandin H2 and 17α,21-dihydroxypregnenolone were targeted as core biomarkers. This study provides scientific evidence to support the finding that HGWWD mainly inhibits the inflammatory response during CIPN by regulating arachidonic acid metabolism.

Investigating the Potential of Microbially Induced Carbonate Precipitation Combined with Modified Biochar for Remediation of Lead-Contaminated Loess

Lead (Pb) contamination in loess poses a significant environmental challenge that impedes sustainable development. Microbially induced carbonate precipitation (MICP) is an innovative biomimetic mineralization technology that shows considerable promise in remediating soil contaminated with heavy metals. However, the toxicity of lead ions to Bacillus pasteurii reduces the efficiency of mineralization, subsequently diminishing the effectiveness of remediation. Although biochar can immobilize heavy metal ions, its adsorption instability presents a potential risk. In this study, we first compared the pH, electrical conductivity (EC), unconfined compressive strength (UCS), permeability coefficient, and toxicity leaching performance of lead-contaminated loess specimens remediated using biochar (BC), red mud (RM), red-mud-modified biochar (MBC), and MICP technology. Additionally, we evaluated the mechanism of MICP combined with varying amounts of MBC in remediating lead-contaminated loess combing Zeta potential, X-ray diffraction (XRD) analyses, and scanning electron microscopy (SEM) tests. The results showed that MICP technology outperforms traditional methods such as RM, BC, and MBC in the remediation of lead-contaminated loess. When MICP is combined with MBC, an increase in MBC content results in a higher pH (8.71) and a lower EC (232 us/cm). Toxic leaching tests reveal that increasing MBC content reduces the lead leaching concentration in loess, with optimal remediation being achieved at 5% MBC. Microscopic analysis indicates that the remediation mechanisms of MICP combined with MBC involve complexation, electrostatic adsorption, ion exchange, and precipitation reactions. The synergistic application of MICP and MBC effectively adsorbs and immobilizes lead ions in loess, enhancing its properties and demonstrating potential for pollution remediation and engineering applications.

Zeolite, Humus and Biochar Remediation of Heavy Metal Contaminated Soil: A Review

With the swift advancement of industrialization and urbanization, soil heavy metal contamination has grown increasingly severe, presenting a grave menace to the environment and human health. As efficacious soil remediation substances, zeolite, humus, and biochar exhibit considerable potential in the treatment of heavy metal pollution. In this article, the research progress of zeolite, humus, and biochar in the remediation of heavy metal pollution in soil was reviewed, the remediation mechanisms, influencing factors, and practical application effects were analyzed, and the future research direction was prospected. Through comprehensive analysis and discussion, the aim is to offer useful references for the control of soil heavy metal pollution.

In-situ remediation of cadmium contamination in paddy fields: from rhizosphere soil to rice kernel.

Cadmium (Cd) has become an important heavy metal pollutant because of its strong migration and high toxicity. The industrial production process aggravated the Cd pollution in rice fields. Human exposure to Cd through rice can cause kidney damage, emphysema, and various cardiovascular and metabolic diseases, posing a grave threat to health. As modern technology develops, the Cd accumulation model in rice and in-situ remediation of Cd pollution in cornfields have been extensively studied and applied, so it is necessary to sort out and summarize them systematically. Therefore, this paper reviewed the primary in-situ methods for addressing heavy metal contamination in rice paddies, including chemical remediation (inorganic-organic fertilizer remediation, nanomaterials, and composite remediation), biological remediation (phytoremediation and microbial remediation), and crop management remediation technologies.The factors that affect Cd transformation in soil and Cd migration in crops, the advantages and disadvantages of remediation techniques, remediation mechanisms, and the long-term stability of remediation were discussed. The shortcomings and future research directions of in situ remediation strategies for heavily polluted paddy fields and genetic improvement strategies for low-cadmium rice varieties were critically proposed. To sum up, this review aims to enhance understanding and serve as a reference for the appropriate selection and advancement of remediation technologies for rice fields contaminated with heavy metals.

Advanced activation of peroxymonosulfate by NiFe-LDH/CeO2 heterostructure photocatalysts toward medical wastewater remediation

The great harm of antibiotic residues in medical wastewater to the ecological environment and human health has become the focus of social attention. Herein, we designed a new peroxymonosulfate (PMS) activation system by in-situ anchoring NiFe-LDH nanosheets into CeO2 (NFC) as a heterogeneous photocatalyst to degrade pollutants. The NFC/PMS/Vis system showed excellent and rapid degradation effect on tetracycline (TC) under the synergistic effect of photocatalysis and PMS activation, and the removal rate of TC was about 98.8 % within 40 min. The chemical compositions, microstructures, and optical properties of synthesized photocatalysts were studied by a series of characterization methods such as XRD, XPS, SEM, TEM and UV-DRS. The effects of various reaction systems and operating parameters such as initial concentration, catalyst dosage, and PMS concentration on the degradation efficiency of TC over optimized NFC-4 composite were investigated. The active species in the reaction system and the dominant SO4− were confirmed by quenching tests and electron paramagnetic resonance (EPR) measurements, and a plausible photocatalytic mechanism for PMS activation and pollutant remediation was further proposed.

Remediation effect and mechanism of immobilized laccase on actual trichloromethane-contaminated soil samples

Trichloromethane (TCM) in soil causes adverse effects on the soil ecosystem and human health. Therefore, it is urgent to develop an efficient and low-cost soil TCM removal technology. In this study, we prepared sodium alginate-biochar-laccase immobilized pellets (SA-BC-LC) using composite immobilization technology, exploring the fitting impact of artificial neural network model (ANN) and general linear model (GLM) models on laccase loading and the correlation properties of SA-BC-LC. The SA-BC-LC exhibited a porous multi-layer network structure internally. Compared to free laccase, the relative activity of SA-BC-LC remained above 50 % after 5 reuses and still maintained at 48 % after 50 days of storage. Moreover, SA-BC-LC demonstrated significant capacity for adsorption and degradation of TCM in soil with ratios approximately at 31.3 % and 68.7 %, respectively. During the remediation process of TCM-contaminated soil from Taizhou Chemical plant, there was a rapid decrease in TCM concentration within the first hour. Under IM (Immobilization) treatment (added with 5 % SA-BC-LC), the removal rate of TCM reached up to 88.9 % in the first hour. The adsorption of TCM by SA-BC-LC was mainly chemical adsorption, which induced the improvement of the relative abundance of the co-metabolic dechlorinated microbial Pseudomonas. Our research presents a promising material for effectively remediating soils contaminated with chlorinated hydrocarbons (CHs), with excellent removal efficiency.

Vital Threshold and Underlying Mechanism for the Complete Remediation of Oil and Microplastic Co-Contaminated Soil by Fast Pyrolysis

Vital Threshold and Underlying Mechanism for the Complete Remediation of Oil and Microplastic Co-Contaminated Soil by Fast Pyrolysis

The regulating mechanisms of Triton X-100 affected oxidation of PAHs in site soil aggregates using sodium citrate assisted Fe2+-persulfate

Here, we present a first investigation of the inhibition mechanism of surfactant Triton X-100 (TX-100) on the oxidation degradation of polycyclic aromatic hydrocarbons (PAHs) in site soil aggregates using sodium citrate assisted Fe2+-activated persulfate (SC/Fe2+/PS). First, TX-100 was not only competed the adsorption sites of soil aggregates with PS, but also consumed PS, which inhibit the PAHs remediation rate in the TX-100 elution followed by the SC/Fe2+/PS oxidation system from 55.6 % in the oxidation system to 50.3 %. Furthermore, in the oxidation followed by elution system, PAHs was adsorbed on the iron minerals produced during the oxidation, which would be form a bound PAHs that was difficult to react with PS, and then re-eluted to the soil by the TX-100. Additionally, it was found that the oxidative and the elution efficiency of PAHs exhibited negative correlations with aggregate particle sizes. Finally, soil microorganism communities were more strongly changed by SC/Fe2+/PS oxidation and PAHs concentration than that of TX-100 elution, with obvious alterations bacteria than fungi, the effects of SC/Fe2+/PS and PAHs concentration on microorganism communities were opposite. This study provided a proof of regulating mechanisms for the site soil remediation using surfactants combined with the iron-PS system.