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1.
J Hazard Mater ; 443(Pt A): 130155, 2023 02 05.
Artículo en Inglés | MEDLINE | ID: mdl-36257108

RESUMEN

The ferrite process has been developed to purify wastewater containing heavy metal ions and recycle valuable metals by forming chromium ferrite. However, organic matter has an important influence on the crystallization behavior and stability of chromite synthesized from chromium-containing wastewater. We focused on the influence and effect mechanism of two typical organic acid salts (citrate (CA) and tartrate (TA)) on the process of chromium mineralization. It was found that the presence of organic matter leads to the increase of the residual content of Cr in CA system (0.50 mmol/L) and TA system (0.61 mmol/L) in the solution, and the removal of chromium was mainly due to the surface adsorption of Fe(III) hydrolysate. The decreased crystallinity of mineralized products is ascribed to the completion of organic compounds with Fe(II) and Fe(III), which hinders the formation of ferrite precursors. There was bidentate and monodentate chelation between -COO- and metal ions in the CA system and TA system respectively, which resulted in a stronger affinity between CA and iron. This study provides the underlying mechanism for Cr(III) solid oxidation by the ferrite method in an organic matter environment and is of great significance to prevent and control chromium pollution in the environment.


Asunto(s)
Compuestos Férricos , Tartratos , Compuestos Férricos/química , Aguas Residuales , Cristalización , Ácido Cítrico , Cromo/química , Metales , Compuestos Orgánicos , Iones
2.
Sci Total Environ ; 856(Pt 2): 158938, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36152853

RESUMEN

Exposure of the soil environment to metal nanoparticles (MNPs) has been extensive because of their indiscriminate use and the disposal of MNP products in various applications. In MNP-amended soil, various crops can absorb the nanoparticles, and accumulation of the MNPs in farm products has potential risks for bioconcentration in humans and livestock. Here, we evaluated the comparative bioaccumulation, translocation, and phytotoxicity of MNPs (ZnO and CuO NPs) and metal ions (Zn(NO3)2 and Cu(NO3)2) in four different crops, namely lettuce, radish, bok choy, and tomato. We carried out pot experiments to evaluate the phytotoxicity in the crops from the presence of MNPs and metal ions. Phytotoxicity from different treatments differed depending on the plant species, and metal types. In addition, exposure to Zn and Cu showed positive dose-dependent effects on their bioaccumulation in each crop. However, there were no significant differences in metal bioaccumulation depending on whether the crops were exposed to MNPs or metal ions. By calculating the bioconcentration factor (BCF) and translocation factor (TF), we were able to estimate the biological uptake and translocation abilities of MNPs and metal ions for each crop. It was found that lettuce and radish had greater BCFs than bok choy and tomato, while bok choy and tomato had higher TFs. Also, the uptake and translocation of Zn were better than those of Cu. However, the values for BCF and TF for each crop showed no significant differences between MNP and metal ion exposure. A micro X-ray fluorescence (µ-XRF) spectrometer analysis demonstrated that only Zn elements appeared in the primary veins and edges of all leaves and the storage root of radish. Our study aims to estimate bioaccumulation, translocation, and the implied potential risks from MNPs accumulated in different plant species.


Asunto(s)
Nanopartículas del Metal , Nanopartículas , Contaminantes del Suelo , Humanos , Suelo , Bioacumulación , Óxidos , Contaminantes del Suelo/toxicidad , Contaminantes del Suelo/análisis , Raíces de Plantas/química , Nanopartículas del Metal/toxicidad , Metales/análisis , Iones , Productos Agrícolas , Lechuga
3.
Carbohydr Polym ; 300: 120262, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36372514

RESUMEN

Cellulose nanofibrils (CNFs) have gained much attention as part of biocompatible soft hydrogels used in various biomedical applications such as biodegradable scaffolds, biomedicine, tissues, and regenerative medicine. The CNF hydrogels were mediated with metal cations for improved mechanical strength and structural reversibility. Intermolecular interactions in these CNF hydrogels are controlled by metal cation-carboxylate coordination bonding, leading to the creation of interconnected three-dimensional nanofibril structures that produce high structural reversibility. The nonlinear inter- and intra-cycle were investigated viscoelastic responses of these CNF hydrogels by quantitative nonlinear viscoelastic parameters and transient responses. The dynamic and transitional analyses conducted indicate that the structural deformation and recovery characteristics of the CNF hydrogels are affected by the valency number of the metal cations. This property can be carefully chosen to tune the intermolecular interactions between the cellulose nanofibrils to create an efficient interwoven network structure with high structural reversibility that can go through repeated cycles of reformation and yielding.


Asunto(s)
Celulosa , Nanofibras , Celulosa/química , Hidrogeles/química , Metales , Reología , Ácidos Carboxílicos , Cationes/química , Nanofibras/química
4.
Enzyme Microb Technol ; 162: 110134, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36166886

RESUMEN

A convenient cell extract based metal organic frameworks (CE-MOF) strategy was used to produce self-assembled hybrid microparticles of enzymes with improved characteristics. It was shown that many metal ions and enzymes could be used to construct catalytically active CE-MOF microparticles. As a proof-of-principle study, the ß-xylosidase BH3683 was used to prepare FeSO4-CE-MOF-BH3683 microparticles to explore the factors influencing preparation of the microparticles. As a result, DNA, RNA, polysaccharides and proteins were found to play important roles in the formation of the microparticles and affected enzyme activities through interaction with enzyme molecules. Compared with the free BH3683, the optimum temperature of FeSO4-CE-MOF-BH3683 increased 5 °C, and the relative activity at 70 °C increased two times. Moreover, FeSO4-CE-MOF-BH3683 have stronger tolerance to different concentrations of various organic solvents and high-concentration xylose than the free BH3683, and the CE-MOF microparticles prepared by BH3683 and xylanase XynII could catalyze high-concentration xylan more efficiently than their free counterparts. In addition, FeSO4-CE-MOF-BH3683 exhibited about 40 % of its initial activity after reused for 10 times, showing satisfactory reusability. To sum up, this strategy might have wide application potential in the fields of biocatalysis, biofuel production, fertilizer industry, etc.


Asunto(s)
Estructuras Metalorgánicas , Extractos Celulares , Catálisis , Proteínas , Metales
5.
Food Chem ; 402: 134208, 2023 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-36116278

RESUMEN

Several approaches to assess the authenticity of food products have been developed, given that fraudulent products may impact consumers' confidence, affect commercial trades and lead to health risks. This paper proposes an approach to identify the chemical elements that optimally discriminate rice samples according to their producing region in the South of Brazil, the largest rice producer outside Asia. A combinatorial procedure on the concentration of 26 elements determined using inductively coupled mass spectrometry (ICP-MS) and liquid chromatography hyphenated with ICP-MS from 640 rice samples was coupled with Support Vector Machine. The assessed elements included nonmetal and metal elements of 3 types of rice collected from 5 rice-producing regions. The framework selected Mn, Fe, Cu, Zn, Ni, Mo, Cd, Cs, As, Rb, Se, and iAs as the most informative elements for tracking samples' origin. The concentration of such elements is strongly affected by fertilization procedures and soil composition.


Asunto(s)
Oryza , Oligoelementos , Oryza/química , Cadmio/análisis , Suelo , Espectrometría de Masas , Metales/análisis , Oligoelementos/análisis
6.
J Hazard Mater ; 442: 130048, 2023 01 15.
Artículo en Inglés | MEDLINE | ID: mdl-36182880

RESUMEN

Recycled concrete aggregate (RCA) has been used as an alternative sustainable material in the construction industry, but RCA long-term environmental impacts are unknown. In this study, the bacterial enrichment potential to reduce the alkalinity of two different types of RCA was examined, from laboratory-produced concrete and from a stockpile of demolished concrete that had been in service in transportation applications. Washed and un-washed lab and field RCA were biostimulated by being exposed to ATCC® Medium 661 in batch experiments. pH, metal composition and microbial community changes in the leachates were monitored over time. Results show that initial pH of field RCA leachate could be decreased to less concerning values, as low as 8, but concentrations of some metals in the leachate exceeded groundwater quality standards. However, the biostimulated RCA released lower metal concentration and was more resistant to pH increases than non-biostimulated RCA during a long-term leaching experiment with DI water. The microbial community was enriched on anaerobic, halotolerant and alkaliphile microorganisms, resistant to extreme environmental conditions. The outcome of this research suggests a baseline for field RCA pretreatment before field application, using a biostimulation method that would generate a less environmentally detrimental runoff.


Asunto(s)
Agua Subterránea , Microbiota , Reciclaje/métodos , Metales , Agua , Materiales de Construcción
7.
J Environ Sci (China) ; 125: 112-134, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36375898

RESUMEN

As the main contributor of the formation of particulate matter as well as ozone, volatile organic compounds (VOCs) greatly affect human health and the environmental quality. Catalytic combustion/oxidation has been viewed as an efficient, economically feasible and environmentally friendly way for the elimination of VOCs. Supported metal catalyst is the preferred type of catalysts applied for VOCs catalytic combustion because of the synergy between active components and support as well as its flexibility in the composition. The presence of support not only plays the role of keeping the catalyst with good stability and mechanical strength, but also provides a large specific surface for the good dispersion of active components, which could effectively improve the performance of catalyst as well as decrease the usage of active components, especially the noble metal amount. Mesoporous molecular sieves, owing to their large surface area, unique porous structures, large pore size as well as uniform pore-size distribution, were viewed as superior support for dispersing active components. This review focuses on the recent development of mesoporous molecular sieve supported metal catalysts and their application in catalytic oxidation of VOCs. The effect of active component types, support structure, preparation method, precursors, etc. on the valence state, dispersion as well as the loading of active species were also discussed and summarized. Moreover, the corresponding conversion route of VOCs was also addressed. This review aims to provide some enlightment for designing the supported metal catalysts with superior activity and stability for VOCs removal.


Asunto(s)
Ozono , Compuestos Orgánicos Volátiles , Humanos , Compuestos Orgánicos Volátiles/química , Catálisis , Oxidación-Reducción , Material Particulado , Metales
8.
J Environ Sci (China) ; 125: 37-46, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36375922

RESUMEN

Photooxidative removal of pharmaceuticals and organic dyes is an effective way to eliminate growing micropollutants. However, photooxidation often results in byproducts as secondary hazardous substances such as phytotoxins. Herein, we found that photooxidation of common antibiotic tetracycline hydrochloride (TCH) over a metal-free 8-hydroxyquinoline (8-HQ) functionalized carbon nitride (CN) photocatalyst significantly reduces the TCH phytotoxic effect. The phytotoxicity test of photocatalytic treated TCH-solution evaluated towards seed growth of Cicer arietinum plant model endowed natural root and shoot growth. This study highlights the conceptual insights in designing of metal-free photocatalyst for environmental remediation.


Asunto(s)
Oxiquinolina , Tetraciclina , Tetraciclina/toxicidad , Oxiquinolina/toxicidad , Nitrilos/toxicidad , Antibacterianos/toxicidad , Metales
9.
Chemosphere ; 310: 136668, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36209869

RESUMEN

The constant need for sacrificial electrodes is one of the limitations of applying the EC in wastewater treatment. Accordingly, this study proposes a sustainable alternative in reusing scrap metallic wastes as electrode materials. Four different types of metallic wastes (beverage cans, used aluminum (Al) foil, scrap iron, and scrap mild steel) are proposed as sacrificial electrodes for grey water (GW) treatment using the EC technique. At electrical current densities (CD) ranging between 5 and 20 mA/cm2, the treatment performance was evaluated for a reaction time of 10 min in terms of the removal efficiency of some key parameters such as color, turbidity, chemical oxygen demand (COD), and electrical conductivity, energy and material consumption, and metal contamination of GW from electrodes. The results demonstrated that using metallic wastes as sacrificial electrodes can achieve a considerable reduction in color, turbidity, COD, and electric conductivity of about 97.2%, 99%, 88%, and 89%, respectively. However, their reuse as electrodes revealed some important concerns. Al foil undergoes quick and substantial perforation and loss of surface area during electrolysis. The scrap iron and scrap mild steel were found to cause metal contamination by increasing Fe ions in the treated GW. Generally, metal scrap wastes can serve effectively as alternative sustainable electrodes. However, further research is recommended regarding the operating costs, which are considered crucial aspects of the EC process in terms of energy consumption and the most efficient method of fabricating the metallic wastes into a form suitable for reuse in the EC technique.


Asunto(s)
Eliminación de Residuos Líquidos , Aguas Residuales , Eliminación de Residuos Líquidos/métodos , Residuos Industriales/análisis , Concentración de Iones de Hidrógeno , Electrodos , Electrocoagulación , Aluminio , Hierro , Acero , Metales
10.
Chemosphere ; 310: 136835, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36243091

RESUMEN

Photocatalytic degradation is one of the most promising technologies available for removing a variety of synthetic and organic pollutants from the environmental matrices because of its high catalytic activity, reduced energy consumption, and low total cost. Due to its acceptable bandgap, broad light-harvesting efficiency, significant renewability, and stability, Fe2O3 has emerged as a fascinating material for the degradation of organic contaminants as well as numerous dyes. This study thoroughly reviewed the efficiency of Fe2O3-based nanocomposite and nanomaterials for water remediation. Iron oxide structure and various synthetic methods are briefly discussed. Additionally, the electrocatalytic application of Fe2O3-based nanocomposites, including oxygen evolution reaction, oxygen reduction reaction, hydrogen evolution reaction, and overall water splitting efficiency, was also highlighted to illustrate the great promise of these composites. Finally, the ongoing issues and future prospects are directed to fully reveal the standards of Fe2O3-based catalysts. This review is intended to disseminate knowledge for further research on the possible applications of Fe2O3 as a photocatalyst and electrocatalyst.


Asunto(s)
Nanocompuestos , Purificación del Agua , Purificación del Agua/métodos , Nanocompuestos/química , Catálisis , Metales , Oxígeno
11.
Chemosphere ; 310: 136905, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36265704

RESUMEN

Dredging activities can result in the relocation of contaminants such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals from shipping channels, harbours, and ports into the marine environment where these components may exert a negative effect on the marine ecosystem. In this work, contamination associated with dredging is evaluated at and around dredged spoil disposal sites in the Belgian part of the North Sea, taking into account spatial as well as temporal variation. A homogeneous dispersion of the different contaminants was observed at the different sites. However, the contamination pattern was different for disposal sites that were linked with commercial ports, resulting in significantly higher PAH and PCB concentrations. When comparing concentrations with environmental assessment criteria, contamination of PAHs does not exceed these criteria in the Belgian Part of the North Sea, and for PCBs, only CB118 reveals a concerningly high concentration that exceeds the environmental assessment criteria. This is in contrast with metals where the contamination of As, Cr, Ni, and Zn exceeded the environmental limit values both at dredged spoil disposal sites and reference locations.


Asunto(s)
Bifenilos Policlorados , Hidrocarburos Policíclicos Aromáticos , Contaminantes Químicos del Agua , Bifenilos Policlorados/análisis , Sedimentos Geológicos , Monitoreo del Ambiente/métodos , Ecosistema , Contaminantes Químicos del Agua/análisis , Mar del Norte , Bélgica , Hidrocarburos Policíclicos Aromáticos/análisis , Metales
12.
Sci Total Environ ; 856(Pt 1): 158928, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36155051

RESUMEN

Enriched trace elements in coal are considered to have a high environmental impact, but the extent of the influence of the enrichment level is unclear. To study the chemical speciation and environmental behavior of trace elements in coal at different enrichment levels, representative coal samples from multiple provinces in China were collected, including bituminous coal I-L2 from Inner Mongolia with high concentrations of Be, Y, Zn, Tl, U, Er, and Yb, and 72-9 coal from Anhui enriched with Cu, Cd, Pb, V, and Zn. The chemical speciation of trace elements in coal was analyzed using a variety of techniques, including X-ray Photoelectron Spectroscopy (XPS), Near Edge X-ray Absorption Fine Structure (NEXAFS), and sequential chemical extraction procedures. Cluster analysis was used for grouping the coal samples based on the enrichment coefficients of trace elements. Coal samples with similar genesis and in closer regions were more likely to be grouped. Metal carbonates and metal sulfate were observed in coals through XPS analysis. The main C species in coal were identified as phenolic C, carboxylic C, unsaturated C, and O-alkyl C/carbonyl C through NEXAFS. The amplitude variation of peaks for the fly ash was smaller than that for the feed coal, which showed that the structure of carbon became homogeneous after high-temperature combustion. It was difficult to identify the chemical speciation difference of trace elements with different enrichment degrees in coals through XPS and NEXAFS, but the results of the sequential chemical extraction could compensate. Several enriched trace elements in coal were relatively high in the chemical fractions (exchangeable, carbonates and monosulfides associated, or FeMn oxide bound) that were easy to extract and relatively low in the less insoluble chemical fractions (organic matter-bound, disulfides associated, or silicates associated), indicating that enriched trace elements in coal had higher environmental impact capacity.


Asunto(s)
Carbón Mineral , Oligoelementos , Carbón Mineral/análisis , Oligoelementos/análisis , Ceniza del Carbón/análisis , Carbono/análisis , Metales
13.
Sci Total Environ ; 856(Pt 1): 159010, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36174681

RESUMEN

Earthworm conversion is an eco-friendly biological process that converts livestock waste into a benign nutrient-rich organic fertilizer. However, little is known about the impacts of earthworm-converted livestock manure on the antibiotic resistome in the earthworm gut microbiota. Herein, lab-scale vermicomposting was performed to comprehensively evaluate the shift of antibiotic resistance genes (ARGs) in the earthworm gut-feeding on cow manure (CM)-by metagenomic analysis. The effects of copper (Cu) as a food addictive were also evaluated. CM substantially enriched the antibiotic resistome in the foregut and midgut, while it decreased in the hindgut. A similar trend was observed for metal resistance genes (MRGs). Notably, Cu in the CM had little effect on composition of ARGs and MRGs in earthworm gut. The earthworm gut microbiome altered by CM was responsible for the shift of ARGs and MRGs. In wormcast, Cu (100 and 300 mg/kg) significantly increased the abundance of ARGs and MRGs. Our study provides valuable insight into the response of ARGs and MRGs to CM in earthworm gut, and underscores the need for the judicious use of heavy metals as feed additives in livestock and poultry farming.


Asunto(s)
Estiércol , Oligoquetos , Animales , Femenino , Bovinos , Antibacterianos/farmacología , Genes Bacterianos , Farmacorresistencia Microbiana/genética , Ganado , Metales
14.
Bioresour Technol ; 367: 128305, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36370943

RESUMEN

Earthworm-induced microbial enrichment is the key to success in vermitechnology, yet the influence of initial earthworm stocking density on microbial community profiles in vermibeds is unknown. Therefore, vermicomposting of lignocellulosic feedstock was performed with different stocking densities of two earthworms (Eisenia fetida and Eudrilus eugeniae) compared with composting. Eventually, earthworm growth, microbial (activity and community profiles), and physicochemical dynamics were assessed. The earthworm population significantly increased under low stocking, while denser stocking (15/kg) was stressful. The XRD-based crystallinity assessment revealed that comminuting efficiency of Eisenia and Eudrilus was prudent at 7 and 10 worm/kg stockings, respectively. Moreover, the 5 and 7 worm/kg stockings effectively mobilized microbial activity, promoting NPK-mineralization and C-humification balance. Correlation statistics indicated that earthworm stocking density-driven microbial community shift and fatty acid profiles strongly influenced metal removal in vermibeds. Hence, the findings implied that 5-7 worm/kg stockings of earthworms produced high-quality sanitized vermicompost.


Asunto(s)
Microbiota , Oligoquetos , Animales , Ácidos Grasos , Suelo/química , Metales
15.
Carbohydr Polym ; 301(Pt A): 120330, 2023 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-36436861

RESUMEN

Liquid metal (LM) nanodroplets and MXene nanosheets are integrated with sulfonated bacterial nanocellulose (BNC) and acrylic acid (AA). Upon fast sonication, AA polymerization leads to a crosslinked composite hydrogel in which BNC exfoliates Mxene, forming organized conductive pathways. Soft conducting properties are achieved in the presence of colloidally stable core-shell LM nanodroplets. Due to the unique gelation mechanism and the effect of Mxene, the hydrogels spontaneously undergo surface wrinkling, which improves their electrical sensitivity (GF = 8.09). The hydrogels are further shown to display interfacial adhesion to a variety of surfaces, ultra-elasticity (tailorable elongation, from 1000 % to 3200 %), indentation resistance and self-healing capabilities. Such properties are demonstrated in wearable, force mapping, multi-sensing and patternable electroluminescence devices.


Asunto(s)
Celulosa , Hidrogeles , Electrónica , Acrilatos , Bacterias , Metales
16.
Sci Total Environ ; 857(Pt 1): 159431, 2023 Jan 20.
Artículo en Inglés | MEDLINE | ID: mdl-36244478

RESUMEN

Asian clams (Corbicula fluminea) have been extensively applied in biomonitoring and other environmental fields based on their high enrichment capacity and rapid response to pollutants. This review first summarizes the kinetic process of metals and organic pollutants enriched by C. fluminea and discusses the environmental behavior and application. The accumulation ability of Cu, Zn, and Mn were significantly higher than that of other metals, which were attributed to their high uptake rate constant and low elimination rate constant. The visceral mass was found to be the major burden tissue. However, large knowledge gaps existed regarding the accumulation capacity of C. fluminea for organic pollutants and nanoparticles. Moreover, physiological mechanisms underlying the accumulation of environmental pollutants were proposed. C. fluminea can improve the niche of benthic algae by ingesting pelagic algae, mitigating water eutrophication. It can also remove pathogens and parasites based on the biological assimilation of nonspecific immunity, interrupting disease transmission. The novel insight into the application of C. fluminea in wastewater treatment further broadens the range of pest management strategies and offers the feasibility of blocking the spread of invasive bivalves.


Asunto(s)
Corbicula , Contaminantes Químicos del Agua , Animales , Corbicula/fisiología , Contaminantes Químicos del Agua/análisis , Agua Dulce , Metales , Agua
17.
Food Chem ; 404(Pt B): 134691, 2023 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-36306704

RESUMEN

This study determines the biochemical composition and metal concentrations (Hg, Fe, Zn, Cu) in muscle tissue of reared Atlantic bluefin tuna and investigates whether protein-lipid composition affects metal accumulation. A significant positive relationship was found between Hg concentrations and protein content, whereas a strong negative relationship between Hg concentrations and lipid content was revealed. Opposite results were obtained, correlating Zn concentrations with biochemical components. No correlations between the concentrations of the other two metals and the protein or lipid components were observed. Evidently, biochemical components may influence the accumulation of certain metals, but not in the same way. Although the analyzed tuna samples represent a rich source of essential metals, Hg may pose a risk to consumers. Our results suggest that a lower level of Hg can be associated with greater lipid and lower protein content. Consumers could reduce the health risk from Hg by choosing constantly high-fat bluefin tuna.


Asunto(s)
Mercurio , Oligoelementos , Animales , Atún/metabolismo , Mercurio/análisis , Músculos/química , Metales/análisis , Oligoelementos/análisis , Lípidos/análisis , Mar Mediterráneo
18.
Environ Res ; 216(Pt 3): 114682, 2023 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-36330877

RESUMEN

Metal resistance genes (MRGs) are potential bio-indicators to diagnose contamination stress on riverine ecosystems. Within reservoir systems, river damming weakens hydrodynamic condition and enriches metal contaminants. But, little is known about the synergic impacts of geographic variation and anthropogenic pollution on MRGs. In this study, the abundance, composition and microbes of MRGs in four cascade reservoirs along the Jinsha River, southwestern China were investigated via high-throughput metagenomics. The results showed significant enrichment of chromium, cadmium and lead in Ludila and Xiluodu reservoirs with moderate ecological risks based on the criteria of drinking water quality and aquatic life protection. Nevertheless, at watershed scale, these metals played little role in up-regulating MRGs abundance owing to the limited toxic stress on microbes. Accordingly, geographic variation showed stronger impacts on MRGs composition than metals as revealed by the distance-decay relationship (Pearson correlation, rgeo = 0.24-0.57, rmetal = 0.10-0.41) and co-occurrence network (Node degree to MRGs subtype, ngeo = 180, nmetal = 6). River damming, as an artificial isolation of geographic space, significantly affected MRGs composition. The longer operation history, smaller storage capacity and higher regulation frequency caused the higher dissimilarity of MRGs composition between the reservoir's upstream and downstream areas. In conclusion, the metal pollution level is a prerequisite regulating MRGs; while under the lowly-polluted conditions, geographic variation had stronger impacts on MRGs than metal pollution via altered assembly of microbial communities. This study provides an important guidance for the future environmental management and ecological protection of river-reservoir ecosystems.


Asunto(s)
Metagenómica , Microbiota , Ríos , Metales , Calidad del Agua , China , Monitoreo del Ambiente
19.
Environ Res ; 216(Pt 1): 114391, 2023 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-36154861

RESUMEN

The Eastern Amazon is rich in bauxite ore. The extraction and processing of bauxite lead to the mobilization of Aluminum (Al) and other metals in environmental. We evaluated the metals (Al, Mn, Ba, and Cr) concentration in tissue, water, and sediment associated with antioxidant and oxidative damage responses in Bryconops caudomaculatus. The samplings were done in two hydrological periods (post-rain and post-dry periods) and at three points, located at two rivers: one in the surroundings of the mining area (P1) and other inside the mining area, upstream (P2), and downstream (P3). Defense antioxidant system biomarkers analyzed were total antioxidant capacity (ACAP) and glutathione-S-transferase (GST) activity. As an oxidative damage biomarker, the lipoperoxidation (LPO) was evaluated. Metals concentrations in the water and sediment were higher in the post-rain period compared to post-dry period. The water samples were acidic, with dissolved Al concentrations above the values established by local legislation at all points. In the gills, the metals accumulation was higher in fish from in the surrounding and upstream sites, and in the liver, was higher in fish from downstream site. Fish from the surrounding had increased antioxidant defenses, with higher ACAP in all tissues and higher GST in the gills. Consequently, they had lower levels of LPO. Fish from the mining area had decreased antioxidant defenses, with lower ACAP in all tissues and lower GST in the gills. Consequently, they had higher levels of LPO, indicating oxidative stress. The fish muscle was not responsive to GST and LPO at all sites. We conclude that the oxidative stress observed in the gills and liver of B. caudomaculatus from the area modified by the mining activity reflected the local anthropogenic impact status.


Asunto(s)
Characiformes , Contaminantes Químicos del Agua , Animales , Characiformes/metabolismo , Antioxidantes/metabolismo , Peroxidación de Lípido , Óxido de Aluminio , Estrés Oxidativo/fisiología , Branquias/metabolismo , Metales/toxicidad , Metales/metabolismo , Biomarcadores/metabolismo , Hígado/química , Agua , Contaminantes Químicos del Agua/análisis , Glutatión Transferasa/metabolismo
20.
Environ Res ; 216(Pt 1): 114479, 2023 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-36208784

RESUMEN

A feasible and cost-effective process for utilization of toluene and heavy reformate is the conversion of its streams by transalkylation reaction into highly valuable xylenes. The process is usually catalysed by zeolites and the challenges to overcome in transalkylation of heavy reformate with toluene over zeolites are their selectivity, activity, long-term stability, and coke formation. Current study aimed to investigate xylenes production by transalkylation reaction on the synthesized metal-doped zeolite catalysts and to characterize prepared catalysts by FTIR, SEM, EDS and BET analysis. Toluene/heavy reformate modelled mixture was utilized as a feed. For the first time Beta and ZSM-5 catalysts with 10% (w/w) cerium and 0.1% (w/w) palladium were synthesized by calcination and wet impregnation method. Catalytic tests were performed by continuous-flow gas/solid catalytic fixed bed reactor at atmospheric pressure, 2 h-1 and 5 h-1 and 250, 300, 350 and 400 °C. Experimental results revealed that the highest heavy reformate conversion (98.94%) and toluene conversion (9.82%) were obtained over H-ZSM-5, at 400 °C and 2 h-1 WHSV. The highest xylene selectivity (11.53) was achieved over H-ZSM-5, and the highest p-xylene percentage (62.40%), using Ce-ZSM-5 catalyst. ZSM-5 catalysts showed more resistance to coke deposition than Beta zeolites. The present study delivers novel approach and catalysts, which have immense potential for developing safer and inexpensive transalkylation process in industry.


Asunto(s)
Coque , Zeolitas , Xilenos , Tolueno , Catálisis , Metales
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