Combined biochar and wheat-derived endophytic bacteria reduces cadmium uptake in wheat grains in a metal-polluted soil.

In this study, two wheat-derived cadmium (Cd)-immobilizing endophytic Pseudomonas paralactis M14 and Priestia megaterium R27 were evaluated for their effects on wheat tissue Cd uptake under hydroponic conditions. Then, the impacts of the biochar (BC), M14+R27 (MR), and BC+MR treatments on wheat Cd uptake and the mechanisms involved were investigated at the jointing, heading, and mature stages of wheat plants under field-plot conditions. A hydroponic experiment showed that the MR treatment significantly decreased the above-ground tissue Cd content compared with the M14 or R27 treatment. The BC+MR treatment reduced the grain Cd content by 51.5%-67.7% and Cd translocation factor at the mature stage of wheat plants and increased the organic matter-bound Cd content by 31%-75% in the rhizosphere soils compared with the BC or MR treatment. Compared with the BC or MR treatment, the relative abundances of the biomarkers associated with Gemmatimonas, Altererythrobacter, Gammaproteobacteria, Xanthomonadaceae, Phenylobacterium, and Nocardioides in the BC+MR-treated rhizosphere microbiome decreased and negatively correlated with the organic matter-bound Cd contents. In the BC+MR-treated root interior microbiome, the relative abundance of the biomarker belonging to Exiguobacterium increased and negatively correlated with the Cd translocation factor, while the relative abundance of the biomarker belonging to Pseudonocardiaceae decreased and positively correlated with the Cd translocation factor. Our findings suggested that the BC+MR treatment reduced Cd availability and Cd transfer through affecting the abundances of these specific biomarkers in the rhizosphere soil and root interior microbiomes, leading to decreased wheat grain Cd uptake in the contaminated soil.

Remediation mechanism of high concentrations of multiple heavy metals in contaminated soil by Sedum alfredii and native microorganisms.

Pollution accident of nonferrous metallurgy industry often lead to serious heavy metal pollution of the surrounding soil. Phytoremediation of contaminated soil is an environmental and sustainable technology, and soil native microorganisms in the process of phytoremediation also participate in the remediation of heavy metals. However, the effects of high concentrations of multiple heavy metals (HCMHMs) on plants and native soil microorganisms remain uncertain. Thus, further clarification of the mechanism of phytoremediation of HCMHMs soil by plants and native soil microorganisms is required. Using the plant Sedum alfredii (S. alfredii) to restore HCMHM-contaminated soil, we further explored the mechanism of S. alfredii and native soil microorganisms in the remediation of HCMHM soils. The results showed that (i) S. alfredii can promote heavy metals from non-rhizosphere soil to rhizosphere soil, which is conducive to the effect of plants on heavy metals. In addition, it can also enrich the absorbed heavy metals in its roots and leaves; (ii) native soil bacteria can increase the abundance of signal molecule-synthesizing enzymes, such as trpE, trpG, bjaI, rpfF, ACSL, and yidC, and promote the expression of the pathway that converts serine to cysteine, then synthesize substances to chelate heavy metals. In addition, we speculated that genes such as K19703, K07891, K09711, K19703, K07891, and K09711 in native bacteria may be involved in the stabilization or absorption of heavy metals. The results provide scientific basis for S. alfredii to remediate heavy metals contaminated soils, and confirm the potential of phytoremediation of HCMHM contaminated soil.

Simultaneous immobilization of multiple heavy metal(loid)s in contaminated water and alkaline soil inoculated Fe/Mn oxidizing bacterium.

Two strains of Fe/Mn oxidizing bacteria tolerant to high concentrations of multiple heavy metal(loid)s and efficient decontamination for them were screened. The surface of the bio-Fe/Mn oxides produced by the oxidation of Fe(II) and Mn(II) by Pseudomonas taiwanensis (marked as P4) and Pseudomonas plecoglossicida (marked as G1) contains rich reactive oxygen functional groups, which play critical roles in the removal efficiency and immobilization of heavy metal(loid)s in co-contamination system. The isolated strains P4 and G1 can grow well in the following environments: pH 5-9, NaCl 0-4%, and temperature 20-30°C. The removal efficiencies of Fe, Pb, As, Zn, Cd, Cu, and Mn are effective after inoculation of the strains P4 and G1 in the simulated water system (the initial concentrations of heavy metal(loid) were 1 mg/L), approximately reaching 96%, 92%, 85%, 67%, 70%, 54% and 15%, respectively. The exchangeable and carbonate bound As, Cd, Pb and Cu are more inclined to convert to the Fe-Mn oxide bound fractions in P4 and G1 treated soil, thereby reducing the phytoavailability and bioaccessible of heavy metal(loid)s. This research provides alternatives method to treat water and soil containing high concentrations of multi-heavy metal(loid)s.

Enhancing microbial superoxide generation and conversion to hydroxyl radicals for enhanced bioremediation using iron-binding ligands.

Harnessing bacteria for superoxide production in bioremediation holds immense promise, yet its practical application is hindered by slow production rates and the relatively weak redox potential of superoxide. This study delves into a cost-effective approach to amplify superoxide production using an Arthrobacter strain, a prevalent soil bacterial genus. Our research reveals that introducing a carbon source along with specific iron-binding ligands, including deferoxamine (DFO), diethylenetriamine pentaacetate (DTPA), citrate, and oxalate, robustly augments microbial superoxide generation. Moreover, our findings suggest that these iron-binding ligands play a pivotal role in converting superoxide into hydroxyl radicals by modulating the electron transfer rate between Fe(III)/Fe(II) and superoxide. Remarkably, among the tested ligands, only DTPA emerges as a potent promoter of this conversion process when complexed with Fe(III). We identify an optimal Fe(III) to DTPA ratio of approximately 1:1 for enhancing hydroxyl radical production within the Arthrobacter culture. This research underscores the efficacy of simultaneously introducing carbon sources and DTPA in facilitating superoxide production and its subsequent conversion to hydroxyl radicals, significantly elevating bioremediation performance. Furthermore, our study reveals that DTPA augments superoxide production in cultures of diverse soils, with various soil microorganisms beyond Arthrobacter identified as contributors to superoxide generation. This emphasizes the universal applicability of DTPA across multiple bacterial genera. In conclusion, our study introduces a promising methodology for enhancing microbial superoxide production and its conversion into hydroxyl radicals. These findings hold substantial implications for the deployment of microbial reactive oxygen species in bioremediation, offering innovative solutions for addressing environmental contamination challenges.

Impact of residual antibiotics on microbial decomposition of livestock manures in Eutric Regosol: Implications for sustainable nutrient recycling and soil carbon sequestration.

The land application of livestock manure has been widely acknowledged as a beneficial approach for nutrient recycling and environmental protection. However, the impact of residual antibiotics, a common contaminant of manure, on the degradation of organic compounds and nutrient release in Eutric Regosol is not well understood. Here, we studied, how oxytetracycline (OTC) and ciprofloxacin (CIP) affect the decomposition, microbial community structure, extracellular enzyme activities and nutrient release from cattle and pig manure using litterbag incubation experiments. Results showed that OTC and CIP greatly inhibited livestock manure decomposition, causing a decreased rate of carbon (28%-87%), nitrogen (15%-44%) and phosphorus (26%-43%) release. The relative abundance of gram-negative (G-) bacteria was reduced by 4.0%-13% while fungi increased by 7.0%-71% during a 28-day incubation period. Co-occurrence network analysis showed that antibiotic exposure disrupted microbial interactions, particularly among G- bacteria, G+ bacteria, and actinomycetes. These changes in microbial community structure and function resulted in decreased activity of urease, ß-1,4-N-acetyl-glucosaminidase, alkaline protease, chitinase, and catalase, causing reduced decomposition and nutrient release in cattle and pig manures. These findings advance our understanding of decomposition and nutrient recycling from manure-contaminated antibiotics, which will help facilitate sustainable agricultural production and soil carbon sequestration.

Halophilic archaea as tools for bioremediation technologies.

Haloarchaea are extremophilic microorganisms belonging to the Archaea domain that require high salt concentrations to be alive, thus inhabiting ecosystems like salty ponds, salty marshes, or extremely salty lagoons. They are more abundantly and widely distributed worldwide than initially expected. Most of them are grouped into two families: Halobacteriaceae and Haloferacaceae. The extreme conditions under which haloarchaea survive contribute to their metabolic and molecular adaptations, thus making them good candidates for the design of bioremediation strategies to treat brines, salty water, and saline soils contaminated with toxic compounds such as nitrate, nitrite, oxychlorates such as perchlorate and chlorate, heavy metals, hydrocarbons, and aromatic compounds. New advances in understanding haloarchaea physiology, metabolism, biochemistry, and molecular biology suggest that biochemical pathways related to nitrogen and carbon, metals, hydrocarbons, or aromatic compounds can be used for bioremediation proposals. This review analyses the novelty of the most recent results showing the capability of some haloarchaeal species to assimilate, modify, or degrade toxic compounds for most living beings. Several examples of the role of these microorganisms in the treatment of polluted brine or salty soils are also discussed in connection with circular economy-based processes. KEY POINTS: • Haloarchaea are extremophilic microorganisms showing genuine metabolism • Haloarchaea can metabolise compounds that are highly toxic to most living beings • These metabolic capabilities are useful for designing soil and water bioremediation strategies.

Enhanced biodegradation of benzo[a]pyrene with Trametes versicolor stimulated by citric acid.

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent organic pollutants with carcinogenic, mutagenic and teratogenic effects. The white-rot fungi in the fungal group have significant degradation ability for high molecular weight organic pollutants. However, exogenous fungi are easily antagonized by indigenous microorganisms. Low molecular weight organic acids, a small molecular organic matter secreted by plants, can provide carbon sources for soil microorganisms. Combining organic acids with white rot fungi may improve the nutritional environment of fungi. In this study, immobilized Trametes versicolor was used to degrade benzo[a]pyrene in soil, and its effect on removing benzo[a]pyrene in soil mediated by different low molecular weight organic acids was investigated. The results showed that when the degradation was 35 days, the removal effect of the experimental group with citric acid was the best, reaching 43.7%. The degradation effect of Trametes versicolor on benzo[a]pyrene was further investigated in the liquid medium when citric acid was added, and the effects of citric acid on the biomass, extracellular protein concentration and laccase activity of Trametes versicolor were investigated by controlling different concentrations of citric acid. In general, citric acid can act as a carbon source for Trametes versicolor and promote its extracellular protein secretion and laccase activity, thereby accelerating the mineralization of benzo[a]pyrene by Trametes versicolor. Therefore, citric acid can be used as a biostimulant in the remediation of PAHs contaminated soil with Trametes versicolor.

Inhibition of microbially mediated total organic carbon decomposition in different types of cadmium contaminated soils with wheat straw addition.

Wheat straw returning is a common agronomic measure in the farmland. Understanding organic carbon transformation is of great significance for carbon budget under the premise of widespread distribution of cadmium (Cd) contaminated soils. An incubation experiment was conducted to assess the influence of Cd contamination on the decomposition and accumulation of total organic carbon (TOC) as well as the composition and abundance of bacterial communities in eight soil types with wheat straw addition. The results showed that inhibition of Cd contamination on microbially mediated organic carbon decomposition was affected by soil types. The lower cumulative C mineralization and higher TOC content could be observed in the acidic soils relative to that in the alkaline soils. The content of Cd in soil exhibits different effects on the inhibition in decomposition of TOC. The high dosage level of Cd had stronger inhibitory impact due to its high toxicity. The decomposition of TOC was restricted by a reduction in soil bacterial abundance and weakening of bacterial activities. Redundancy analysis (RDA) indicated that Proteobacteria and Gemmatimonadetes were abundant in alkaline Cd-contaminated soils with wheat straw addition, while Bacteroidetes dominated cumulative C mineralization in acidic Cd-contamination soils. Moreover, the abundance of predicted functional bacteria indicated that high-dose Cd-contamination and acid environment all inhibited the decomposition of TOC. The present study suggested that pH played an important role on carbon dynamics in the Cd-contaminated soils with wheat straw addition.

Phosphate solubilizing Aspergillus Niger PH1 ameliorates growth and alleviates lead stress in maize through improved photosynthetic and antioxidant response.

Among the several threats to humanity by anthropogenic activities, contamination of the environment by heavy metals is of great concern. Upon entry into the food chain, these metals cause serious hazards to plants and other organisms including humans. Use of microbes for bioremediation of the soil and stress mitigation in plants are among the preferred strategies to provide an efficient, cost-effective, eco-friendly solution of the problem. The current investigation is an attempt in this direction where fungal strain PH1 was isolated from the rhizosphere of Parthenium hysterophorus which was identified as Aspergillus niger by sequence homology of the ITS 1 and ITS 4 regions of the rRNA. The strain was tested for its effect on growth and biochemical parameters as reflection of its potential to mitigate Pb stress in Zea mays exposed to 100, 200 and 500 µg of Pb/g of soil. In the initial screening, it was revealed that the strain has the ability to tolerate lead stress, solubilize insoluble phosphate and produce plant growth promoting hormones (IAA and SA) and other metabolites like phenolics, flavonoids, sugar, protein and lipids. Under 500 µg of Pb/g of soil, Z. mays exhibited significant growth retardation with a reduction of 31% in root length, 30.5% in shoot length, 57.5% in fresh weight and 45.2% in dry weight as compared to control plants. Inoculation of A. niger to Pb treated plants not only restored root and shoot length, rather promoted it to a level significantly higher than the control plants. Association of the strain modulated the physio-hormonal attributes of maize plants that resulted in their better growth which indicated a state of low stress. Additionally, the strain boosted the antioxidant defence system of the maize there by causing a significant reduction in the ascorbic acid peroxidase (1.5%), catalase (19%) and 1,1-diphenyl-2 picrylhydrazyl (DPPH) radical scavenging activity (33.3%), indicating a lower stress condition as compared to their non-inoculated stressed plants. Based on current evidence, this strain can potentially be used as a biofertilizer for Pb-contaminated sites where it will improve overall plant health with the hope of achieving better biological and agricultural yields.

Microbially induced carbonate precipitation with Arthrobacter creatinolyticus: An eco-friendly strategy for mitigation of chromium contamination.

Chromium contamination from abandoned industrial sites and inadequately managed waste disposal areas poses substantial environmental threat. Microbially induced carbonate precipitation (MICP) has shown promising, eco-friendly solution to remediate Cr(VI) and divalent heavy metals. In this study, MICP was carried out for chromium immobilization by an ureolytic bacterium Arthrobacter creatinolyticus which is capable of reducing Cr(VI) to less toxic Cr(III) via extracellular polymeric substances (EPS) production. The efficacy of EPS driven reduction was confirmed by cellular fraction analysis. MICP carried out in aqueous solution with 100 ppm of Cr(VI) co-precipitated 82.21% of chromium with CaCO3 and the co-precipitation is positively correlated with reduction of Cr(VI). The organism was utilized to remediate chromium spiked sand and found that MICP treatment decreased the exchangeable fraction of chromium to 0.54 ±â€¯0.11% and increased the carbonate bound fraction to 26.1 ±â€¯1.15% compared to control. XRD and SEM analysis revealed that Cr(III) produced during reduction, influenced the polymorph selection of vaterite during precipitation. Evaluation of MICP to remediate Cr polluted soil sample collected from Ranipet, Tamil Nadu also showed effective immobilization of chromium. Thus, A. creatinolyticus proves to be viable option for encapsulating chromium contaminated soil via MICP process, and effectively mitigating the infiltration of Cr(VI) into groundwater and adjacent water bodies.

Enhanced remediation of PFAS-metal co-contaminated soil by ceramsite supported Fe3O4-MoS2 heterojunction as a high-performance piezocatalyst.

In this study, a novel piezoremediation system was developed to remediate an actual soil co-polluted by high contents of per- and polyfluoroalkyl substances (PFAS, 5725 µg/kg soil) and heavy metals (6455 mg/kg soil). Two piezocatalysts, MoS2/ceramsite (MC) and Fe3O4-MoS2/ceramsite (FMC), were synthesized using a facile hydrothermal-coprecipitation method. These two materials were employed to treat the co-contaminated soil in soil slurry environment under sonication. FMC exhibited significantly higher piezoremediation performance than MC, wherein 91.6% of PFAS, 97.8% of Cr6+ ions and 81% of total metals (Cr, Cu, Zn and Ni) were removed from the soil after 50 min of the FMC piezoremediation process. FMC also exhibited the advantages of easy separation from the slurry phase and excellent reusability. In comparison with MC, the Fe3O4-MoS2 heterojunction in FMC can stabilize MoS2 particles on the surface of ceramsite granules, promote the separation of electron/hole pairs, accelerate charge transfer, therefore enhancing piezocatalytic performance. The electron spin resonance analysis and free radical quenching tests show that •OH was the dominant oxidative radical responsible for PFAS degradation. The count of bacteria and the bacterial community structure in the treated soil can be basically restored to the initial states after 30 days of incubation under nutrient stimulation. Overall, this study not only provides a deep insight on soil remediation process, but also offers an efficient and reliable technique for simultaneous decontamination of organic and metal pollutants in soil.

Temporal variations in absorption and translocation of heavy metal(loid)s in pak choi (Brassica rapa L.) under open-field and greenhouse cultivation.

Elucidating the absorption and translocation of heavy metal(loid)s by common vegetables across different growth environments and stages is crucial for conducting accurate environmental risk assessments and for associated control. This study investigated temporal variations in the absorption and translocation capacities of pak choi (Brassica rapa L.) for As, Cd, Cr, Cu, Pb, and Zn in polluted soils during the plant growth cycle under greenhouse and open-field cultivation modes. Results showed high root metal(loid) bioconcentration factors and root-to-shoot translocation factors for Cd (0.25 and 1.44, respectively) and Zn (0.26 and 1.01), but low values for As (0.06 and 0.88) and Pb (0.06 and 0.87). The Cd concentration in the aerial edible parts peaked during the early slow growth period, whereas other heavy metal(loid)s peaked during the later stable maturity period. Root bioconcentration and root-to-shoot translocation factors did not significantly differ between cultivation modes. However, greenhouse cultivation exhibited lower average Cd and Zn concentrations in the edible parts and cumulative uptake amounts of most metal(loid)s than open-field cultivation during the typical harvest period spanning days 60 and 90. Short-term transitioning from open-field to greenhouse cultivation may reduce health risks associated with heavy metal(loid) intake via pak choi consumption. These findings facilitate sustainable agricultural practices and food safety management.

Effect of Genotype on Cadmium and Trace Element Accumulation in Wheat from Weakly Alkaline Cadmium-contaminated Soil.

Cadmium (Cd) contamination of farmland soils leads to Cd accumulation in crops and reduced micronutrient uptake, posing grave risks to food safety. Herein, we investigated the enrichment and transportation patterns of Cd and trace elements in different parts of six wheat genotypes grown in weakly alkaline Cd-contaminated soils via pot experiments. The results revealed that the wheat grain variety with high Cd accumulation (Ningmai13) demonstrated a 1.94-fold increase compared to the variety with low accumulation (Yanong0428). The transfer factor of Cd from wheat straw to grain ranged from 0.319 to 0.761, while the transfer factor of Cd from root to straw ranged from 0.167 to 0.461. Furthermore, the concentrations of other metals in wheat grains followed the order of Zn > Mn > Fe > Cu. There was a significant positive correlation between Cd and Mn in grains, indicating a potential synergistic effect. Overall, this study provides valuable insights into the regulation of micronutrient intake to modulate Cd uptake in wheat.

Enrichment of Polycyclic Aromatic Hydrocarbon (PAH)-Degrading Strictly Anaerobic Sulfate-Reducing Cultures from Contaminated Soil and Sediment.

Sulfate-reducing bacteria (SRB) are crucial players in global biogeochemical cycling and some have been implicated in the anaerobic biodegradation of organic pollutants, including recalcitrant and hazardous polycyclic aromatic hydrocarbons (PAHs). Obtaining PAH-degrading SRB cultures for laboratories is of paramount importance in the development of the young field of anaerobic biodegradation of PAHs. SRB grow exceptionally slowly on PAH substrates and are highly sensitive to oxygen. Consequently, enrichment and maintenance of PAH-degrading SRB cultures and characterization of the biodegradation process remain a tedious and formidable task, especially for new researchers. To address these technical constraints, we have developed robust and effective protocols for obtaining and characterizing PAH-degrading SRB cultures. In this set of protocols, we describe step-by-step procedures for preparing inocula from contaminated soil or sediment, preparing anoxic medium, establishing enrichment cultures with PAHs as substrates under completely anaerobic sulfate-reducing conditions, successive culture transfers to obtain highly enriched cultures, rapid verification of the viability of SRB in slow-growing cultures, assessment of PAH degradation by extracting residuals using organic solvent and subsequent analysis by gas chromatography-mass spectrometry, and spectrophotometric determination of sulfate and sulfide in miniaturized, medium-throughput format. These protocols are expected to serve as a comprehensive manual for obtaining and characterizing PAH-degrading sulfate-reducing cultures. © 2024 The Author(s). Current Protocols published by Wiley Periodicals LLC. Basic Protocol 1: Obtaining PAH-degrading strictly anaerobic sulfate-reducing enrichment cultures from contaminated soil and sediment Support Protocol 1: Operation and maintenance of an anaerobic workstation Support Protocol 2: Setup of gas purging systems for preparing anoxic solutions Support Protocol 3: Verification of viability in slow-growing SRB enrichment cultures Support Protocol 4: Extraction of genomic DNA from low-biomass cultures Basic Protocol 2: Extraction of residual PAH from liquid culture and analysis by GC-MS Basic Protocol 3: Spectrophotometric determination of sulfate concentration in SRB cultures Basic Protocol 4: Spectrophotometric determination of sulfide concentrations in SRB cultures by the methylene blue method Alternate Protocol: Spectrophotometric determination of sulfide concentrations in SRB cultures by the colloidal copper sulfide method.

Application of CuNPs and AMF alleviates arsenic stress by encompassing reduced arsenic uptake through metabolomics and ionomics alterations in Elymus sibiricus.

Recent studies have exhibited a very promising role of copper nanoparticles (CuNPs) in mitigation of abiotic stresses in plants. Arbuscular mycorrhizae fungi (AMF) assisted plants to trigger their defense mechanism against abiotic stresses. Arsenic (As) is a non-essential and injurious heavy-metal contaminant. Current research work was designed to elucidate role of CuNPs (100, 200 and 300 mM) and a commercial inoculum of Glomus species (Clonex® Root Maximizer) either alone or in combination (CuNPs + Clonex) on physiology, growth, and stress alleviation mechanisms of E. sibiricus growing in As spiked soils (0, 50, and 100 mg Kg- 1 soil). Arsenic induced oxidative stress, enhanced biosynthesis of hydrogen peroxide, lipid peroxidation and methylglyoxal (MG) in E. sibiricus. Moreover, As-phytotoxicity reduced photosynthetic activities and growth of plants. Results showed that individual and combined treatments, CuNPs (100 mM) as well as soil inoculation of AMF significantly enhanced root growth and shoot growth by declining As content in root tissues and shoot tissues in As polluted soils. E. sibiricus plants treated with CuNPs (100 mM) and/or AMF alleviated As induced phytotoxicity through upregulating the activity of antioxidative enzymes such as catalase (CAT) and superoxide dismutase (SOD) besides the biosynthesis of non-enzymatic antioxidants including phytochelatin (PC) and glutathione (GSH). In brief, supplementation of CuNPs (100 mM) alone or in combination with AMF reduced As uptake and alleviated the As-phytotoxicity in E. sibiricus by inducing stress tolerance mechanism resulting in the improvement of the plant growth parameters.

The effects of monoculture and intercropping on photosynthesis performance correlated with growth of garlic and perennial ryegrass response to different heavy metals.

BACKGROUND: The potential of phytoremediation using garlic monoculture (MC) and intercropping (IC) system with perennial ryegrass to enhance the uptake of cadmium (Cd), chromium (Cr), and lead (Pb) were investigated. RESULTS: Positive correlations were found between MC and IC systems, with varying biomass. Production of perennial ryegrass was affected differently depending on the type of toxic metal present in the soil. Root growth inhibition was more affected than shoot growth inhibition. The total biomass of shoot and root in IC was higher than MC, increasing approximately 3.7 and 2.9 fold compared to MC, attributed to advantages in root IC crop systems. Photosystem II efficiency showed less sensitivity to metal toxicity compared to the control, with a decrease between 10.07-12.03%. Among gas exchange parameters, only Cr significantly affected physiological responses by reducing transpiration by 69.24%, likely due to leaf chlorosis and necrosis. CONCLUSION: This study exhibited the potential of garlic MC and IC with perennial ryegrass in phytoremediation. Although the different metals affect plant growth differently, IC showed advantages over MC in term biomass production.

Insights into the uptake, translocation, and accumulation dynamics of cyantraniliprole and thiamethoxam seed coating pesticides in maize plants.

Seed coating with pesticides is used extensively for the protection of both seeds and plants against pests. In this study, the uptake and transport of seed-coating pesticides (insecticides), including cyantraniliprole (CYN) and thiamethoxam (THX), were investigated. The translocation of these pesticides from the soil to the plant and their accumulation in different plant parts were also calculated. After sowing the seeds with seed coating pesticides, soil and plant samples were taken across the study area. These samples were extracted and analyzed in liquid chromatography with tandem mass spectrometry (LC-MS/MS). CYN and THX were used in maize plants for the first time to observe soil degradation kinetics, and CYN showed a higher half-life than THX in soil. Both pesticides have been taken up by the corn maize plant and transferred and accumulated to the upper parts of the plant. Although the THX concentration was between 2.240 and 0.003 mg/kg in the root, between 3.360 and 0.085 mg/kg in the stem, it was between 0.277 and 3.980 mg/kg in the leaf, whereas CYN was detected at higher concentrations. The concentration of CYN was 1.472 mg/ kg and 0.079 mg/kg in the roots and stems of the maize plant, respectively. However, the bioconcentration factor (BCF) indicates the soil-to-plant accumulation of CYN from 28 to 34.6 and that of 12.5 to 4567.1 for THX on different sampling days. The translocation factor (TFstem) represents the ratio of pesticides absorbed from the stem and transported to the roots. For CYN, TFstem ranges from 3.6 to 20.5, while for THX, it varies between 1.5 and 26.8, indicating a higher translocation rate for THX. The ratio of leaf to root concentration are 3.6 to 20.5 for CYN and 1.8 to 87.7 for THX, demonstrating effective translocation for both pesticides. The TF values for both pesticides are above 1, signifying successful root-to-stem-to-leaf movement. Notably, THX exhibits a notably higher transport rate compared to CYN.

Accumulation of heavy metals from single and combined olive mill wastewater and pomace in soil and bioaccumulation in tissues of two earthworm species: Endogeic (Aporrectodea trapezoides) and Epigeic (Eisenia fetida).

Soil and earthworms are threatened by anthropogenic contamination resulting from olive mill waste dumping on the soil due to their pollutant properties. While several studies have explored the effects of olive mill waste on soil properties and the accumulation of heavy metals in soil, there is currently a gap in the literature regarding the potential bioaccumulation of heavy metals from olive mill waste in earthworms. In this study, soil with earthworms from two ecological categories (endogeic: Aporrectodea trapezoides and epigeic: Eisenia fetida) was treated with increasing doses of olive mill wastewater (OMWW) and olive mill pomace (OMP), applied individually or combined, in an indoor experiment in plastic containers, under laboratory conditions. The results revealed the presence of significant concentrations of heavy metals in the two types of wastes ranging as follows: Fe˃ Zn˃ Cu˃ Cd˃ Cr for OMWW, and Fe˃ Zn˃ Cu˃ Cr for OMP (with Cd below the detection limit). The study demonstrated distinct effects of OMWW and OMP, both individually and in combination, on soil heavy metal content, ranging as follows: soil OMWW > soil Combination > soil OMP for Cd; soil Combination > soil OMWW > soil OMP for Cr and Fe; and soil Combination > soil OMP > soil OMWW for Cu and Zn. Additionally, our investigation showed that both earthworm species exhibited significant uptake of these metals into their tissues, particularly the endogeic species. Interestingly, the most significant difference between species was in the accumulation of Cu, with the epigeic species accumulating significantly lower amounts.

Metal content, bioaccumulation, translocation, and health risk assessment of root vegetables grown in KwaZulu-Natal small-scale farms of South Africa.

Metal uptake by vegetables is becoming a threat to the life of consumers. Therefore, continuous monitoring of metals in vegetables and soils is becoming a necessity. In this study, the occurrence of 18 metals in amadumbe (Colocasia esculenta L.), sweet potatoes (Ipomoea batatas L.), potatoes (Solanum tuberosum L.), and carrots (Daucus carrota L.) grown in small-scale South African agricultural farms was monitored using inductively coupled plasma-optical emission spectroscopy. All the 18 investigated elements were detected in soils and different vegetative plants parts. Bioaccumulation factors indicated the transfer of selected metals from soils into the plant roots. Toxic metals Cd, Cr, and Pb had their concentrations exceeding the maximum permissible levels set by the World Health Organization in the edible parts of all root vegetables. Cd and Pb varied between 18.89 and 19.19 mg kg-1 and 10.46 and 11.46 mg kg-1, respectively, while Cr remained constant at 16.78 mg kg-1. The exact metals together with As and Ni had their total hazard quotients exceeding the threshold value of 1, which indicated that the daily consumption of the investigated root vegetables is likely to pose health risks to both adults and children. Therefore, this study points out to a possibility of toxic health effects that could arise when these vegetables are consumed daily.

Biological assessment and radiological impact in Keana, North Central Nigeria: environmental implication and metabolites production.

The objective of the research was to examine microbial characteristics, metabolites produced, and the potential radiological risks present in mining soils located in Keana, North Central Nigeria. Soil samples were collected from various locations within Keana, Nasarawa State. Bacterial isolation was carried out, and molecular techniques were employed to characterize the bacteria found in the collected soil samples. Additionally, the susceptibility of these isolates to antibiotics was determined, and the bacteria screened for their ability to produce metabolites. The isolated bacteria were classified into three groups: Actinobacteria, Firmicutes, and Proteobacteria. The analysis of the spectra revealed that 1595 compounds were produced, including carboxylic acids, nitro compounds, aldehydes, anhydrides, esters, ketones, amides, phenols, alcohols, alkanes, alkenes, alkynes, and arenes. Some of the metabolites produced were oleic acid, 1,3-dioxolane, linoelaidic acid and oleic acid, 1-nonadecene, butylated hydroxytoluene, diisooctyl phthalate, bis(2-ethylhexyl) phthalate among others, and 1,2-benzenedicarboxylic acid (85.32%) as the most produced metabolite. Among the antibiotics tested, levofloxacin and ciprofloxacin exhibited the strongest antibacterial properties against the isolates. Airborne gamma-ray spectrometry analysis identified elevated levels of potassium, thorium, and uranium in the soils, indicating potential environmental hazards. However, no significant correlation was found between the presence of bacteria and radioactive elements. These findings emphasize the importance of comprehensive environmental monitoring in Keana to address potential health risks associated with microbial contamination and radioactive materials. Additionally, the study highlighted the role of microbial diversity in Keana soils in promoting the production of secondary metabolites with potential applications in pharmaceutical and industrial sectors..