Speciation, phytoavailability, and accumulation of toxic elements and sulfur by humic acid-fertilized lemongrass and common sage in a sandy soil treated with heavy oil fly ash: A trial for management of power stations wastes.

Globally, power stations generate huge amounts of the hazardous waste heavy oil fly ash (HOFA), which is rich in Ni, V, Fe, S, and dumped into landfills. Thus, exploring new approaches for a safe recycling and sustainable management of HOFA is needed and of great environmental interest. The potential application of HOFA as an amendment to sandy soils has not been studied yet. This is the first research investigating the potentiality of using HOFA as a soil conditioner. To this end, we conducted a greenhouse experiment in order to investigate the impacts of HOFA addition (1.2, 2.4, 3.6 t ha-1) to sandy soil on the total and available content of nutrients (e.g., S, Fe, Mn, Cu, Zn) and toxic elements (TEs; e.g., Cd, Co, Cr, Ni, Pb, V) in the soil and their phytoextraction and translocation by lemongrass (Cymbopogon citratus) and common sage (Salvia officinalis). We also assessed the impact of humic acid (HA) foliar application (50 and 100 l ha-1) on the growth and elements accumulation by the two plants. The studied HOFA was acidic and highly enriched in S (43,268.0), V (3,527.0), Ni (1774.0), and Fe (15,159.0) (units in mg kg-1). The X-ray absorption near edge structure (XANES) data showed that V in HOFA was composed primarily of V(IV) sorbed onto goethite, V(V) sorbed onto humic substances, in the forms of V2O3, and VCl4. Addition of the lower doses of HOFA (1.2 and 2.4 t ha-1) did not change significantly soil pH, salinity, and the total and available elements content compared to the unamended soil. Although the elements content in the 3.6 t ha-1 HOFA-treated soil was significantly higher than the untreated, the total content of all elements (except for Ni) was lower than the maximum allowable concentrations in soils. HOFA addition, particularly in the highest dose (3.6 t ha-1), decreased significantly the growth and biomass of both plants. Common sage accumulated more elements than lemongrass; however, the elements content in the plants was lower than the critical concentrations for sensitive plants. The foliar application of humic acid enhanced significantly the plant growth and increased their tolerance to the HOFA-induced stress. We conclude that the addition of HOFA up to 2.4 t ha-1 in a single application as amendment to sandy soils is not likely to create any TE toxicity problems to plants, particularly if combined with a foliar application of humic acid; however, repeated additions of HOFA may induce toxicity. These findings should be verified under field conditions.

Transformative and sustainable insights of agricultural waste-based adsorbents for water defluoridation: Biosorption dynamics, economic viability, and spent adsorbent management.

With the progression of civilization, the harmony within nature has been disrupted, giving rise to various ecocidal activities that are evident in every spheres of the earth. These activities have had a profound and far-reaching impact on global health. One significant example of this is the presence of fluoride in groundwater exceeding acceptable limits, resulting in the widespread occurrence of "Fluorosis" worldwide. It is imperative to mitigate the concentration of fluoride in drinking water to meet safety standards. While various defluoridation techniques exist, they often have drawbacks. Biosorption, being a simple, affordable and eco-friendly method, has gained preference for defluoridation. However, its limited commercialization underscores the pressing need for further research in this domain. This comprehensive review article offers a thorough examination of the defluoridation potential of agro-based adsorbents, encompassing their specific chemical compositions and preparation methods. The review presents an in-depth discussion of the factors influencing fluoride biosorption and conducts a detailed exploration of adsorption isotherm and adsorption kinetic models to gain a comprehensive understanding of the nature of the adsorption process. Furthermore, it evaluates the commercial viability through an assessment of regeneration potential and a cost analysis of these agro-adsorbents, with the aim of facilitating the scalability of the defluoridation process. The elucidation of the adsorption mechanism and recommendations for overcoming challenges in large-scale implementation offer a comprehensive outlook on this eco-friendly and sustainable approach to fluoride removal. In summary, this review article equips readers with a lucid understanding of agro-adsorbents, elucidates their ideal conditions for improved performance, offers a more profound insight into the fluoride biosorption mechanism, and introduces the concept of effective spent adsorbent management.

Physiology and molecular basis of thallium toxicity and accumulation in Arabidopsis thaliana.

Thallium (Tl) is a non-essential metal mobilized through industrial processes which can lead to it entering the environment and exerting toxic effects. Plants are fundamental components of all ecosystems. Therefore, understanding the impact of Tl on plant growth and development is of great importance for assessing the potential environmental risks of Tl. Here, the responses of Arabidopsis thaliana to Tl were elucidated using physiological, genetic, and transcriptome analyses. Thallium can be absorbed by plant roots and translocated to the aerial parts, accumulating at comparable concentrations throughout plant parts. Genetic evidence supported the regulation of Tl uptake and movement by different molecular compartments within plants. Thallium primarily caused growth inhibition, oxidative stress, leaf chlorosis, and the impairment of K homeostasis. The disturbance of redox balance toward oxidative stress was supported by significant differences in the expression of genes involved in oxidative stress and antioxidant defense under Tl exposure. Reduced GSH levels in cad2-1 mutant rendered plants highly sensitive to Tl, suggesting that GSH has a prominent role in alleviating Tl-triggered oxidative responses. Thallium down-regulation of the expression of LCHII-related genes is believed to be responsible for leaf chlorosis. These findings illuminate some of the mechanisms underlying Tl toxicity at the physiological and molecular levels in plants with an eye toward the future environment management of this heavy metal.

Hierarchical Porous Fibers for Intrinsically Thermally Insulated and Self-Sensing Integrated Smart Textile.

Here, stretchable hierarchical porous polyurethane fibers were designed, fabricated, and employed as a three-dimensional hierarchical interconnected framework for conductive networks interwoven with silver nanoparticles and carbon nanotubes. The fiber possessed favorable thermal insulation, strain sensing, and electric heating properties. The core-shell layered porous structure of fiber made the fiber have high heat insulation performance (the difference value of temperature |ΔT| = 3.54, 8.9, and 12.7 °C at heating stage temperatures of 35, 50, and 65 °C) and ultrahigh elongation at break (813%). Importantly, after conductive filler decoration, the fiber could exhibit real-time strain-sensing capacities with a high gauge factor. In addition, the fibers could be heated at low voltage, like an electrical heater. The development of flexible, stretchable, and multifunctional porous fibers had great potential applications in intelligent wearable devices for integrated thermal management, strain sensing, and intrinsic self-warming capability.

Electronic structure modulation of iron sites with fluorine coordination enables ultra-effective H2O2 activation.

Electronic structure modulation of active sites is critical important in Fenton catalysis as it offers a promising strategy for boosting H2O2 activation. However, efficient generation of hydroxyl radicals (•OH) is often limited to the unoptimized coordination environment of active sites. Herein, we report the rational design and synthesis of iron oxyfluoride (FeOF), whose iron sites strongly coordinate with the most electronegative fluorine atoms in a characteristic moiety of F-(Fe(III)O3)-F, for effective H2O2 activation with potent •OH generation. Results demonstrate that the fluorine coordination plays a pivotal role in lowering the local electron density and optimizing the electronic structures of iron sites, thus facilitating the rate-limiting H2O2 adsorption and subsequent peroxyl bond cleavage reactions. Consequently, FeOF exhibits a significant and pH-adaptive •OH yield (~450 µM) with high selectivity, which is 1 ~ 3 orders of magnitude higher than the state-of-the-art iron-based catalysts, leading to excellent degradation activities against various organic pollutants at neutral condition. This work provides fundamental insights into the function of fluorine coordination in boosting Fenton catalysis at atomic level, which may inspire the design of efficient active sites for sustainable environmental remediation.

Edge sulfur vacancies riched MoS2 nanosheets assist PEDOT:PSS flexible film ammonia sensing enhancement for wireless greenhouse vegetables monitoring.

Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is a promising NH3 sensing material owing to its super high electrical conductivity, excellent environmental stability, and reversible doping/dedoping nature. However, the low sensitivity and sluggish recovery rate limit its further application in gas sensors. Herein, exfoliated layered MoS2 nanosheets with large-specific surface area and abundant edge sulfur (S) vacancies are utilized to assist PEDOT:PSS and achieve ideal improvement in NH3 sensing performance at room temperature (RT), including high response values, fast response/recovery ability, and excellent sensing stability in complex environment. MoS2 nanosheets are combined with PEDOT:PSS to construct p-n heterojunction, the S vacancies can improve carrier transfer rate and serve as conductive bridge, effective active sites for NH3 adsorption, this series of performance improvement strategies is the significance of this work. Meanwhile, the density-functional theory (DFT), current-voltage (I-V), and in-situ FITR are firstly employed to discuss the sensing mechanisms in detail. Furthermore, integrating MoS2/PEDOT:PSS flexible sensor into a designed printed circuit board to intelligent, visual, and wireless real-time monitoring the NH3 resistance information in a simulated greenhouse vegetables equipment through the smartphone APP has also been successfully implemented.

L-DOPA induces iron accumulation in roots of Ipomoea aquatica and Arabidopsis thaliana in a pH-dependent manner.

BACKGROUND: Iron deficiency is the leading cause of anemia worldwide, particularly in countries with predominant plant-based diets. Plants constitute the main source of dietary iron. Increasing their iron concentration could reduce the occurrence of anemia. The water spinach Ipomoea aquatica is consumed as a vegetable throughout Asia and tolerates high iron concentrations making it an attractive candidate for iron biofortification. L-DOPA is an allelopathic molecule secreted by some legumes. L-DOPA can trigger the expression of Fe deficiency-inducible genes, and could potentially be used as a biostimulant to increase Fe concentration. RESULTS: L-DOPA significantly affected root growth of water spinach, and triggered a massive accumulation of Fe in roots. Both effects were exacerbated when L-DOPA was dissolved in KOH, which is surprising given that L-DOPA is less stable at high pH. To check whether a higher pH could indeed increase the bioactivity of L-DOPA, we used Arabidopsis thaliana, which grows at lower pH than water spinach, and subjected the plants to L-DOPA treatments at pH 5.5 and pH 6.0, which are both within the optimal range for Arabidopsis nutrition. At pH 6.0, the root growth of Arabidopsis was more strongly inhibited than at pH 5.5. We found that at higher pH, L-DOPA oxidizes to form a melanin precipitate. CONCLUSIONS: We concluded that the oxidation of L-DOPA that we observed upon solubilization in KOH, or in nutrient solutions at slightly higher pH produces melanin-related molecules that are more potent than L-DOPA itself to trigger the primary root growth inhibition, Fe uptake and root Fe accumulation in water spinach and Arabidopsis.

First principal observation documenting the three-dimensional uptake of cadmium and spatial distribution of cadmium hydroxyapatite mineral in bone char.

The 3-D matrix scale ion-exchange mechanism was explored for high-capacity cadmium (Cd) removal using bone chars (BC) chunks (1-2 mm) made at 500 °C (500BC) and 700 °C (700BC) in aqueous solutions. The Cd incorporation into the carbonated hydroxyapatite (CHAp) mineral of BC was examined using a set of synchrotron-based techniques. The Cd removal from solution and incorporation into mineral lattice were higher in 500BC than 700BC, and the diffusion depth was modulated by the initial Cd concentration and charring temperature. A higher carbonate level of BC, more pre-leached Ca sites, and external phosphorus input enhanced Cd removal. The 500BC showed a higher CO32-/PO43- ratio and specific surface area (SSA) than the 700BC, providing more vacant sites by dissolution of Ca2+. In situ observations revealed the refilling of sub-micron pore space in the mineral matrix because of Cd incorporation.The X-ray nanodiffraction (XND) analyses revealed that Cd was mainly removed from water by incorporation into the mineral lattice of 500BC via ion exchange, rather than surface sorption and precipitation, and the mineral phase was transformed from hydroxyapatite (HAp) to cadmium hydroxyapatite (Cd-HAp). The Rietveld's refinement of X-ray diffraction (XRD) data resolved up to 91% of the crystal displacement of Ca2+ by Cd2+. The specific phase and stoichiometry of the new Cd-HAp mineral was dependent on the level of ion exchange. This mechanistic study confirmed that 3-D ion exchange was the most important path for heavy metal removal from aqueous solution and immobilization in BC mineral matrix, and put forward a novel and sustainable remediation strategy for Cd removal in wastewater and soil clean-up.

Soluble soil Pb minimized by thermal transformation to Pb-bearing feldspar.

Thermal transformation is an effective remediation measure to stabilize soil Pb and other heavy metals via transformation into less soluble compounds. This study aimed to determine the solubility of Pb in soils subjected to heating at a range of temperatures (100-900 °C) in relation to the changes in Pb speciation using XAFS spectroscopy. Lead solubility in the contaminated soils after thermal treatment corresponded well to the chemical species of Pb present. As the temperature was increased to 300 °C, cerussite and Pb associated with humus started to decompose in the soils. As the temperature was further increased to 900 °C, the amount of water and HCl extractable Pb decreased significantly from the soils, whereas Pb-bearing feldspar started to occur, accounting for nearly 70% of the soil Pb. During thermal treatment, Pb species in the soils were little affected by Fe oxides that showed a significant phase transformation into hematite. Our study proposes the following underlying mechanisms for Pb immobilization in thermally treated soils: i) thermally labile Pb species such as PbCO3 and Pb associated with humus start to decompose at temperatures around 300 °C, ii) aluminosilicates with crystalline and poorly ordered structures undergo thermal decomposition at temperatures around 400 °C, iii) liberating Pb in the soil is then associated with a Si and Al rich liquid derived from thermally decomposed aluminosilicates at higher temperatures, and iv) the formation of Pb-feldspar like minerals is enhanced at 900 °C.

Temporal transformation of indium speciation in rice paddy soils and spatial distribution of indium in rice rhizosphere.

Indium is a potentially toxic element that could enter human food chains, including soil-rice systems. The submerged environment in rice paddy soil results in temporal and spatial variations in the chemical properties of the rice rhizosphere and bulk soils, expected to cause changes in indium's chemical speciation and consequently affect its bioavailability. Therefore, this study aimed to investigate indium speciation and fractionation in soils at different periods of rice growth under continuous submergence using X-ray absorption spectroscopy and a sequential extraction method. The predominant indium species were identified as indium-associated Fe hydroxide, and indium hydroxide and phosphate precipitates. The reductive dissolution of indium-associated Fe hydroxides led to the release of indium into the soil solution under continuous submergence of soils, and the released indium concentration decreased with time due to re-sorption and re-precipitation. Meanwhile, indium hydroxide was found to be the predominant species in rice rhizosphere using µ-X-ray absorption spectroscopy. The relative depletion of indium-associated Fe hydroxides in the rice rhizosphere was attributed to the low mobility of indium from bulk soil to rice rhizosphere and the root uptake of indium associated with Fe hydroxide around rice roots. Consequently, indium uptake by rice roots was lower during the reproductive and grain-ripening stage of rice growth. Understanding the behavior of indium will help develop a strategy to minimize uptake into crops in indium-contaminated paddy soils.

The tissue distribution of Jinzhen oral liquid in healthy and influenza mice.

Jinzhen oral liquid (JZOL) is widely used in China. However, its tissue distribution, a vital part of the efficacy substances research, has not been reported yet. This study characterized its chemical components and its prototypes and metabolites in mice, and investigated its tissue distribution in pathological and healthy mice. Several constituents were characterized, including 55 constituents in JZOL, 11 absorbed prototypes and six metabolites in plasma and tissues. The metabolic pathways were demethylation, dehydration and acetylation. A sensitive, accurate and stable quantitative method was established and applied to the tissue distribution. After administration of JZOL, these seven components were rapidly distributed to various tissues, mainly staying in the small intestine, and less distributed to lung, liver and kidney. Compared with healthy mice, the absorption of baicalin, wogonoside, rhein, glycyrrhizic acid and liquiritin apioside was reduced in influenza mice, but their elimination was slow. However, influenza infection had no obvious effect on the overall distribution of the most important components (baicalin, glycyrrhizic acid and wogonoside) in the plasma or small intestine, but obviously affected the distribution of baicalin in liver. In summary, seven components are rapidly distributed to various tissues, and influenza infection has certain influence on the tissue distribution of JZOL.

Mechanism of Jinzhen Oral Liquid against influenza-induced lung injury based on metabonomics and gut microbiome.

ETHNOPHARMACOLOGICAL RELEVANCE: Jinzhen Oral Liquid (JZOL) is a traditional Chinese patent medicine and widely used clinically, which consists of eight herbs including Bovis Calculus Atifactus, Fritillariae Ussuriensis Bulbus (Fritillaria ussuriensis Maxim.), Caprae Hircus Cornu, Rhei Radix et Rhizoma (Rheum palmatum L.), Scutellariae Radix (Scutellaria baicalensis Georgi), Glycyrrhizae Radix et Rhizoma (Glycyrrhiza uralensis Fisch. ex DC.), Chloriti Lapis, and Gypsum Fibrosum (Their ratio is 9.45 : 47.25: 94.5 : 31.5: 15.75 : 31.5: 15.75 : 23.62). A large number of clinical studies have proved that JZOL has a good antiviral effect and can treat lung injury, pneumonia, and bronchitis caused by a variety of viral infections. AIM OF THE STUDY: Influenza infection frequently exhibit dysregulation of gut microbiota and host metabolomes, but the mechanism of JZOL is still unclear and needs to be further explored. Here, after influenza virus infection induced lung injury, the regulation roles of JZOL in metabolic and gut microbiota balances are investigated to comprehensively elucidate its therapeutic mechanism. MATERIALS AND METHODS: A mouse model of lung injury was replicated via intranasal instillation of influenza A (H1N1). The efficacy of JZOL was evaluated by pathological sections, lung index, the levels of TNF-α and IFN-γ, and viral load in lung tissue. Its modulation of endogenous metabolites and gut microbiota was assessed using plasma metabolomic technique and 16S rRNA high-throughput sequencing technique. RESULTS: JZOL not only significantly relieved lung inflammation and edema in influenza mice, but also alleviated the disturbance of endogenous metabolites and the imbalance of gut microbiota mainly by regulating glycerophospholipid and fatty acid metabolism and Lactobacillus. The anti-influenza effects of JZOL were gut microbiota dependent, as demonstrated by antibiotic treatment. The altered metabolites were significantly correlated with Lactobacillus and pharmacodynamic indicators, further confirming the reliability of these results. CONCLUSIONS: JZOL attenuates H1N1 influenza infection induced lung injury by regulating lipid metabolism via the modulation of Lactobacillus. The results support the clinical application of JZOL, and are useful to further understand the mechanism of TCM in the treatment of influenza.

Quality evaluation of ginkgo biloba leaves based on non-targeted metabolomics and representative ingredient quantification.

Ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-Q-TOF-MS/MS) combined with multivariate statistical analysis was applied to the study of plant metabolomics to reveal the factors affecting the content of ginkgo leaf compounds. As a follow-up analysis, the terpene lactones and ginkgolic acids were quantified simultaneously using ultra-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UPLC-QqQ-MS/MS), and subsequently total flavonol glycosides were quantified by high-performance liquid chromatography (HPLC). The results revealed that a total of 52 compounds were potentially identified by establishing a database, and 10 compounds were verified by reference standards; terpene lactones, ginkgolic acids, and flavonoids were the differential compounds; and ginkgolide A was identified as an important indicator compound for tree age. In addition, quantitative analysis showed that the contents of total flavonol glycosides and terpene lactones were highest during April and August in young ginkgo leaves, and differed based on origin. In summary, numerous compounds were rapidly detected by liquid chromatography coupled with MS, the ginkgo leaf samples were compared, and the differential metabolites were screened out. The content changing rules of the target compounds in ginkgo leaves from different regions with different tree ages and harvesting periods were clarified.

Reduning Injection prevents carrageenan-induced inflammation in rats by serum and urine metabolomics analysis.

Objective: To elucidate the anti-inflammatory mechanism of Reduning Injection (RDN) by analyzing the potential biomarkers and metabolic pathways of the carrageenan-induced inflammatory model from the overall metabolic level. Methods: Rat inflammatory model was established by carrageenan. UPLC-Q-TOF/MS was used to detect and analyze changes of endogenous metabolites in the serum and urine of carrageenan-induced inflammatory rats. Combined with multivariate analysis and databases analysis, inflammatory-related potential biomarkers were screened and identified to analyze possible metabolic pathways. The reliability and biological significance of these biomarkers was verified by metabolic network analysis and correlation analysis with pharmacodynamic indicators. Results: A total of 16 potential biomarkers were screened and identified by multivariate analysis and metabolite databases, among which 13 species could be adjusted by RDN. The metabolism pathway analysis revealed that histidine metabolism, sphingolipid metabolism, and tyrosine metabolism were greatly disturbed. Their biomarkers involved urocanic acid, sphingosine, and norepinephrine, all of which showed a callback trend after RDN treatment. The three biomarkers had a certain correlation with some known inflammatory-related small molecules (histamine, arachidonic acid, Leukotriene B4, and PGE2) and pharmacodynamic indicators (IL-6, IL-1ß, PGE2 and TNF-α), which indicated that the selected biomarkers had certain reliability and biological significance. Conclusion: RDN has a good regulation of the metabolic disorder of endogenous components in carrageenan-induced inflammatory rats. And its anti-inflammatory mechanism is mainly related to the regulation of amino acid and lipid metabolism. This research method is conducive to the interpretation of the overall pharmacological mechanism of Chinese medicine.

Identification and characterization of major alkaloid from Sinomenium acutum stem and their metabolites after oral administration in rat plasma, urine, bile and feces based on UPLC-Q-TOF/MS.

Sinomenium acutum stem is widely used to treat rheumatoid arthritis, gout, ankylosing spondylitis and other diseases in China. However, its metabolism in vivo is still unclear. In this study, UPLC-Q-TOF/MS was used to analyze the main components and their metabolites in rats after oral administration of Sinomenium acutum stem extract. A total of 41 compounds were identified from the ethanol extract of Sinomenium acutum stem based on the established database and the reference substance; a total of 25 prototype components and 107 metabolites (74 phase I metabolites and 33 phase II metabolites) were speculated and identified in the plasma, urine, bile and feces of rats administered. The metabolic pathways included hydroxylation, demethylation, dehydrogenation, glucuronidation and acetylation. In conclusion, this study revealed the metabolism of Sinomenium acutum stem in vivo, which may provide a better basis for the study of Sinomenium acutum stem and provide useful chemical information on the material basis and pharmacological mechanism of drug efficay.

Reducing conditions increased the mobilisation and hazardous effects of arsenic in a highly contaminated gold mine spoil.

Arsenic (As) redox-induced mobilisation and speciation in polluted gold mine sites in tropical climates largely remains unknown. Here, we investigated the impact of changes in soil redox potential (EH) (-54 mV to +429 mV) on mobilisation of As and its dominant species in an abandoned spoil (total As = 4283 mg/kg) using an automated biogeochemical microcosm set-up. Arsenic mobilisation increased (85-137 mg/L) at moderately reducing conditions (-54 mV to + 200 mV)), while its reduced (6-35 mg/L) under oxic conditions (+200 to +400 mV). This indicates the high risk of As potential loss under reducing conditions. The mobilisation of As was governed by the redox chemistry of Fe. XANES and EXAFS analyses showed that sorbed-As(V)-goethite, sorbed-As(III)-ferrihydrite, scorodite and arsenopyrite were the predominant As species in the mine spoil. As(V) dominated at oxic conditions and As(III) predominated at moderately reducing conditions, which may be attributed to either inability of arsenate bacteria to reduce As or incomplete reduction. Lower Fe/As molar ratios during moderately reducing conditions show that the mine spoil may migrate As to watercourses during flooding, which may increase the hazardous effects of this toxic element. Therefore, encouraging aerobic conditions may mitigate As release and potential loss from the mine field.

Hazardous enrichment of toxic elements in soils and olives in the urban zone of Lavrio, Greece, a legacy, millennia-old silver/lead mining area and related health risk assessment.

Lavrio is a Greek town with several abandoned Ag/Pb mines. In this study, 19 potentially toxic elements (PTEs) were measured in soil, weeds, and olives. Levels of seven of the studied PTEs in soil were highly elevated: Zn (56.2-58,726 mg kg-1), Pb (36.2-31,332), As (7.3-10,886), Cu (8.3-1273), Sb (0.99-297.8), Cd (0.17-287.7), and Ag (0.09-38.7). Synchrotron-based X-ray absorption near edge structure analysis of the soils revealed that As was predominantly associated with scorodite, Pb with humic substances, Zn with illite, Zn(OH)2 and humic substances, and Fe with goethite-like minerals. The transfer of the PTEs to weeds was relatively low, with the transfer coefficient being less than 1.0 for all PTEs. Cadmium in table olives surpassed 0.05 mg kg-1 fresh weight (the limit in EU), while Pb surpassed its limit in approximately half of the samples. Health risk assessment confirmed soil contamination in the study area where As and Pb hazard quotients were well above 1.0 and the average hazard index equaled 11.40. Additionally, the cancer risk values exceeding the 1 × 10-4 threshold. The results obtained in the study indicate that Lavrio urgently requires an adequate ecofriendly remediation plan, including revegetation with tolerant species and targeted efforts to chemically stabilize harmful PTEs. The presented approach may serve as a pivotal study for industrial areas with similar contamination levels.

Spectroscopic investigations and density functional theory calculations reveal differences in retention mechanisms of lead and copper on chemically-modified phytolith-rich biochars.

A better understanding of different retention mechanisms of potentially toxic elements (PTEs) by biochars during the remediation of contaminated sites is critically needed. In this study, different spectroscopic techniques including synchrotron-based micro-X-ray fluorescence (µ-XRF), X-ray absorption fine structure (XAFS), and near-edge XAFS spectroscopy (NEXAFS), were used to investigate the spatial distributions and retention mechanisms of lead (Pb) and copper (Cu) on phytolith-rich coconut-fiber biochar (CFB), and ammonia, nitric acid and hydrogen peroxide modified CFB (MCFB) (i.e., ACFB, NCFB and HCFB). The µ-XRF analyses indicated that sorption sites on ACFB and NCFB were more efficient compared to those on CFB and HCFB to bind Pb/Cu. XAFS analyses revealed that the percentage of Pb species as Pb(C2H3O2)2 increased from 22.2% (Pb-loaded CFBs) to 47.4% and 41.9% on Pb-loaded NCFBs and HCFBs, while the percentage of Cu(OH)2 and Cu(C2H3O2)2 increased from 5.8% to 32.8% (Cu-loaded CFBs) to 41.5% and 43.4% (Cu-loaded NCFBs), and 27.1% and 35.1% (Cu-loaded HCFBs), respectively. Due to their similar atomic structures of Pb/Cu, Pb(C2H3O2)2/Pb-loaded montmorillonite and Cu(C2H3O2)2/Cu(OH)2 were identified as the predominant Pb/Cu species observed in Pb- and Cu-loaded MCFBs. The NEXAFS analyses of carbon confirmed that increasing amounts of carboxylic groups were formed on HCFB and NCFB by oxidizing carbon-containing functional groups, which could provide additional active binding sites for Pb/Cu retention. Results from the X-ray photoelectron spectroscopy analyses of nitrogen showed that azido-groups of ACFB played major roles in Pb/Cu retention, while amide-groups and pyridine-groups of NCFB primarily participated in Pb/Cu retention. Overall, density functional theory calculations suggested that silicate and the synergistic effect of hydroxyl and carboxylic-groups on MCFBs were highly efficient in Pb retention, while azido-groups and/or carboxylic-groups played major roles in Cu retention. These results provide novel insights into the PTE retention mechanisms of MCFBs.

Unraveling timescale-dependent Fe-MOFs crystal evolution for catalytic ozonation reactivity modulation.

Iron-based metal-organic frameworks (Fe-MOFs) have been considered competitive catalyst candidates for the effective degradation of organic pollutants via advanced oxidation processes (AOPs) due to their unique porous architecture and tunable active site structure. However, little is known about the role of synergetic relationship between porous architecture and active site exposure of Fe-MOFs on catalysis for AOPs yet. Here, we demonstrated an overlooked compromise over these two features on modulating the catalytic ozonation reactivity of MIL-53(Fe) through a timescale-dependent crystal evolution. Enabled by intramolecular hydrogen bonds, the MIL-53(Fe) was subjected to six evolution steps in terms of crystal morphology, leading to a volcano plot of catalytic ozonation reactivity for Rhodamine B (RhB) degradation versus the crystallization time. Evidence suggested that the surface area of MIL-53(Fe) decreased dramatically, while the density of accessible active site increased when prolonging crystallization time, allowing for the facile modulation of catalytic ozonation reactivity of MIL-53(Fe). Electron paramagnetic resonance and fluorescence quantification tests verified that the screened MIL-53(Fe)s had a much better capacity for ∙OH generation than benchmark ozonation catalyst α-MnO2 and α-FeOOH. Moreover, the MIL-53(Fe) with the highest reactivity (i.e., MIL-53(Fe)-18H) could effectively destruct a broad spectrum of emerging and refractory organic pollutants and allow the thorough purification of secondary effluents discharged from textile dyeing & finishing industry for in situ reuse. Therefore, our study advances the understanding of the compromise effect between porous architecture and active site on catalysis reactivity of Fe-MOFs and promotes the rational design of more effective Fe-MOFs as well as their derivatives for environmental applications.

Soil gallium speciation and resulting gallium uptake by rice plants.

Gallium (Ga) is widely used in high-tech industries and is an emerging contaminant in the environment. This study aimed to determine Ga speciation in soils and Ga accumulation in rice plants (Oryza sativa L.) grown in three Ga-contaminated soils. The results showed that, among the soils, the acidic soil with a coarse texture had the highest soil Ga availability, which enhanced Ga uptake by rice roots. The Ga K-edge X-ray absorption near edge structure and sequential extraction results of the soils showed that the predominant species of Ga associated with iron hydroxides transformed to Ga(OH)3 precipitates, and the residue fraction increased with rice-growing time, resulting in lower Ga uptake by rice roots in the second half period of rice cultivation. A large fraction of Ga was accumulated in the rice roots, with only a small portion of Ga was transferred to the shoots and then to the rice grains. This study revealed that Ga speciation in soil-rice plant systems varied during rice cultivation and determined soil Ga availability to rice plants. Gallium accumulated in rice grains is distributed homogenously in the endosperm of the grains, suggesting a potential risk to public health via the intake of rice grains harvested from Ga-contaminated paddy fields.