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The electrokinetic (EK) process has been proposed for soil decontamination from heavy metals and organic matter. The advantages of the EK process include the low operating energy, suitability for fine-grained soil decontamination, and no need for excavation. During the last three decades, enhanced and hybrid EK systems were developed and tested for improving the efficiency of contaminants removal from soils. Chemically enhanced-EK processes exhibited excellent efficiency in removing contaminants by controlling the soil pH or the chemical reaction of contaminants. EK hybrid systems were tested to overcome environmental hurdles or technical drawbacks of decontamination technologies. Hybridization of the EK process with phytoremediation, bioremediation, or reactive filter media (RFM) improved the remediation process performance by capturing contaminants or facilitating biological agents' movement in the soil. Also, EK process coupling with solar energy was proposed to treat off-grid contaminated soils or reduce the EK energy requirements. This study reviews recent advancements in the enhancement and hybrid EK systems for soil remediation and the type of contaminants targeted by the process. The study also covered the impact of operating parameters, imperfect pollution separation, and differences in the physicochemical characteristics and microstructure of soil/sediment on the EK performance. Finally, a comparison between various remediation processes was presented to highlight the pros and cons of these technologies.
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Restauración y Remediación Ambiental , Metales Pesados , Contaminantes del Suelo , Suelo , Contaminantes del Suelo/química , Restauración y Remediación Ambiental/métodos , Suelo/química , Biodegradación AmbientalRESUMEN
Pesticide pollution has been posing a significant risk to human and ecosystems, and photocatalysis is widely applied for the degradation of pesticides. Machine learning (ML) emerges as a powerful method for modeling complex water treatment processes. For the first time, this study developed novel ML models that improved the estimation of the photocatalytic degradation of various pesticides using ZnO-based photocatalysts. The input parameters encompassed the source of light, mass proportion of dopants to Zn, initial pesticide concentration (C0), pH of the solution, catalyst dosage and irradiation time. Additionally, physicochemical properties such as the molecular weight of the dopants and pesticides, as well as the water solubility of both dopants and pesticides, were considered. Notably, the numerical data were extracted from the literature via relevant tables (directly) or graphs (indirectly) using the web-based tool WebPlotDigitizer. Four ML models including multi-layer perceptron artificial neural network (MLP-ANN), particle swarm optimization-adaptive neuro fuzzy inference system (PSO-ANFIS), radial basis function (RBF), and coupled simulated annealing-least squares support vector machine (CSA-LSSVM) were developed. In comparison, RBF showed the best accuracy of modeling among all models, with the highest determination coefficient (R2) of 0.978 and average absolute relative deviation (AARD) of 4.80%. RBF model was effective in estimating the photocatalytic degradation of pesticides except for 2-chlorophenol, triclopyr and lambda-cyhalothrin, where CSA-LSSVM model demonstrated superior performance. Dichlorvos was completely degraded by ZnO photocatalyst under visible light. The sensitivity analysis by relevancy factor exhibited that light irradiation time and initial pesticide concentration were the most important parameters influencing photocatalytic degradation of pesticides positively and negatively, respectively. The new ML models provide a powerful tool for predicting pesticide degradation in wastewater treatment, which will reduce photochemical experiments and promote sustainable development.
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Aprendizaje Automático , Plaguicidas , Fotólisis , Contaminantes Químicos del Agua , Óxido de Zinc , Óxido de Zinc/química , Plaguicidas/química , Plaguicidas/análisis , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/análisis , Catálisis , Redes Neurales de la Computación , Purificación del Agua/métodosRESUMEN
Perfluorooctanoic acid (PFOA) is a persistent compound, raising considerable global apprehension due to its resistance to breakdown and detrimental impacts on human health and aquatic environments. Pressure-driven membrane technologies treating PFAS-contaminated water are expensive and prone to fouling. This study presented a parametric investigation of the effectiveness of cellulose triacetate membrane in the forward osmosis (FO) membrane for removing PFOA from an aqueous solution. The study examined the influence of membrane orientation modes, feed pH, draw solution composition and concentration, and PFOA concentration on the performance of FO. The experimental results demonstrated that PFOA rejection was 99 % with MgCl2 and slightly >98 % with NaCl draw solutions due to the mechanism of PFOA binding to the membrane surface through Mg2+ ions. This finding highlights the crucial role of the draw solution's composition in PFOA treatment. Laboratory results revealed that membrane rejection of PFOA was 99 % at neutral and acidic pH levels but decreased to 95 % in an alkaline solution at pH 9. The decrease in membrane rejection is attributed to the dissociation of the membrane's functional groups, consequently causing pore swelling. The results were confirmed by calculating the average pore radius of the CTA membrane, which increased from 27.94 nm at pH 5 to 30.70 nm at pH 9. Also, variations in the PFOA concentration from 5 to 100 mg/L did not significantly impact the membrane rejection, indicating the process's capability to handle a wide range of PFOA concentrations. When seawater was the draw solution, the FO membrane rejected 99 % of PFOA concentrations ranging from 5 mg/L to 100 mg/L. The CTA FO treating PFOA-contaminated wastewater from soil remediation achieved a 90 % recovery rate and water flux recovery of 96.5 % after cleaning with DI water at 40 °C, followed by osmotic backwash. The results suggest the potential of using abundant and cost-effective natural solutions in the FO process, all without evident membrane fouling.
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This article has been withdrawn at the request of the Editor-in-Chief.
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Widespread contamination by heavy metals (HMs) and dyes poses a major health risk to people and ecosystems requiring effective treatment. In this work, rice husk (RH) and shrimp shells were extracted to obtain amorphous silica and chitosan, respectively, which were utilized to produce nano-chitosan-coated silica (NCCS). To ensure the stability of the nanoparticles, silica was freeze-dried after being coated with nano-chitosan. Functional groups (-NH2, -OH, P]O) from chitosan nanoparticles (CNPs) were introduced to the surface of silica during this process. Dyes such as brilliant green (BG), methylene blue (MB) and reactive brown (RB) as well as HMs (Cr6+, Pb2+, Cd2+, Ni2+) were removed by adsorbents. CNPs showed the highest adsorption capacity for RB (59.52 mg/g) among dyes and Cr6+ (42.55 mg/g) among HMs. CNPs showed the highest adsorption capacity for HMs among different adsorbents. Although NCCS and CNPs showed similar adsorption capabilities for HMs and dyes, NCCS showed the best stability. The adsorption performance decreased as RB > Cr6+ > MB > BG > Pb2+ > Cd2+ > Ni2+. The adsorption reactions followed both pseudo-first-order and second-order kinetics, and was spontaneous from thermodynamic analysis. In summary, the waste-derived adsorbents demonstrated excellent potential for removing HMs and dyes from water, while supporting effective management solid waste.
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Quitosano , Metales Pesados , Oryza , Contaminantes Químicos del Agua , Humanos , Cadmio , Colorantes , Agua , Ecosistema , Plomo , Dióxido de Silicio , Adsorción , Cinética , Concentración de Iones de HidrógenoRESUMEN
Pharmaceuticals are widely used and often discharged without metabolism into the aquatic systems. The photocatalytic degradation of pharmaceutical compounds propranolol, mebeverine, and carbamazepine was studied using different titanium dioxide nanostructures suspended in water under UV and UV-visible irradiation. Among three different photocatalysts, the degradation was most effective by using Degussa P25 TiO2, followed by Hombikat UV100 and Aldrich TiO2. The photocatalytic performance was dependent on photocatalyst dosage, with an optimum concentration of 150 mg L-1. The natural aquatic colloids were shown to enhance the extent of photocatalysis, and the effect was correlated with their aromatic carbon content. In addition, the photocatalysis of pharmaceuticals was enhanced by the presence of nitrate, but inhibited by the presence of 2-propanol, indicating the importance of hydroxyl radicals. Under optimum conditions, the pharmaceuticals were rapidly degraded, with a half-life of 1.9 min, 2.1 min, and 3.2 min for propranolol, mebeverine, and carbamazepine, respectively. In treating sewage effluent samples, the photocatalytic rate constants for propranolol (0.28 min-1), mebeverine (0.21 min-1), and carbamazepine (0.15 min-1) were similar to those in water samples, demonstrating the potential of photocatalysis as a clean technology for the effective removal of pharmaceuticals from sewage effluent.
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The reclamation and reuse of electrolytic manganese residue (EMR) as a bulk hazard solid waste are limited by its residual ammonia nitrogen (NH4+-N) and manganese (Mn2+). This work adopts a co-processing strategy comprising air-jet milling (AJM) and horizontal-shaking leaching (HSL) for refining and leaching disposal of NH4+-N and Mn2+ in EMR. Results indicate that the co-use of AJM and HSL could significantly enhance the leaching of NH4+-N and Mn2+ in EMR. Under optimal milling conditions (50 Hz frequency, 10 min milling time, 12 h oscillation time, 400 rpm rate, 30 â temperature, and solid-to-liquid ratio of 1:30), NH4+-N and Mn2+ leaching efficiencies were optimized to 96.73% and 97.35%, respectively, while the fineness of EMR was refined to 1.78 µm. The leaching efficiencies of NH4+-N and Mn2+ were 58.83% and 46.96% higher than those attained without AJM processing. The AJM used strong airflow to give necessary kinetic energy to EMR particles, which then collided and sifted to become refined particles. The AJM disposal converted kinetic energy into heat energy upon particle collisions, causing EMR phase transformation, and particularly hydrated sulfate dehydration. The work provides a fire-new and high-efficiency method for significantly and simply leaching NH4+-N and Mn2+ from EMR.
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The increasing prevalence of microplastic pollution in aquatic environments has raised concerns about its impact on marine life. Among the different types of microplastics, polystyrene microplastics (PSMPs) are one of the most commonly detected in aquatic systems. Chaetoceros neogracile (diatom) is an essential part of the marine food web and plays a critical role in nutrient cycling. This study aimed to monitor the ecotoxicological impact of PSMPs on diatoms and observe enzymatic interactions through molecular docking simulations. Results showed that diatom growth decreased with increasing concentrations and exposure time to PSMPs, and the lowest photosynthetic efficiency (Fv/Fm) value was observed after 72 and 96 h of exposure to 200 mg L-1 of PSMPs. High concentrations of PSMPs led to a decrease in chlorophyll a content (up to 64.4%) and protein content (up to 35.5%). Molecular docking simulations revealed potential interactions between PSMPs and the extrinsic protein in photosystem II protein of diatoms, suggesting a strong affinity between the two. These findings indicate a detrimental effect of PSMPs on the growth and photosynthetic efficiency of diatoms and highlight the need for further research on the impact of microplastics on marine microbial processes.
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Diatomeas , Contaminantes Químicos del Agua , Microplásticos/toxicidad , Poliestirenos/toxicidad , Plásticos/toxicidad , Clorofila A , Simulación del Acoplamiento Molecular , Contaminantes Químicos del Agua/metabolismoRESUMEN
Emerging contaminants (ECs) are increasingly recognized as threats to human health and ecosystems. This review evaluates advanced analytical methods, particularly mass spectrometry, for detecting ECs and understanding their toxicity, transformation pathways, and environmental distribution. Our findings underscore the reliability of current techniques and the potential of upcoming methods. The adverse effects of ECs on aquatic life necessitate both in vitro and in vivo toxicity assessments. Evaluating the distribution and degradation of ECs reveals that they undergo physical, chemical, and biological transformations. Remediation strategies such as advanced oxidation, adsorption, and membrane bioreactors effectively treat EC-contaminated waters, with combinations of these techniques showing the highest efficacy. To minimize the impact of ECs, a proactive approach involving monitoring, regulations, and public education is vital. Future research should prioritize the refining of detection methods and formulation of robust policies for EC management.
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Ecosistema , Contaminantes Químicos del Agua , Humanos , Monitoreo del Ambiente/métodos , Contaminantes Químicos del Agua/toxicidad , Contaminantes Químicos del Agua/análisis , Reproducibilidad de los Resultados , Contaminación del AguaRESUMEN
Antibiotics are extensively used for health protection and food production, causing antibiotic pollution in the aquatic environment. This study aims to determine the bioavailability and bioaccumulation of typical antibiotics sulfamethoxazole (SMX) and roxithromycin (RTM) in zebrafish under environmentally realistic conditions. Four different microcosms, i.e. water, water-sediment, water-zebrafish, and water-sediment-zebrafish were constructed, with three replicates in parallel. The concentrations of SMX and RTM in water, sediment and zebrafish were extracted and analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) to assess their kinetic behavior and bioavailability. In the water-sediment system, the dissolved concentration of both SMX and RTM decreased with time following the first-order kinetic while their adsorption by sediment increased with time. In the water-zebrafish system, SMX and RTM bioaccumulation was increasing with time following the pseudo second-order kinetics. RTM bioaccumulation in zebrafish (up to 16.4 ng/g) was an order of magnitude higher than SMX (up to 5.2 ng/g), likely due to RTM being more hydrophobic than SMX. In addition, the bioaccumulation factor (BAF) value of SMX in zebrafish was greater than its sediment partition coefficient, while the opposite trend was observed for RTM, demonstrating the importance of antibiotics properties in affecting their bioavailability. Furthermore, increasing dissolved organic carbon concentration in water reduced SMX bioaccumulation, but increased RTM bioaccumulation at the same time. The findings are important in future studies of environmental fate and bioavailability of toxic chemicals with different pollution sources and physicochemical properties.
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Roxitromicina , Sulfametoxazol , Animales , Sulfametoxazol/análisis , Pez Cebra , Agua/química , Adsorción , Bioacumulación , Espectrometría de Masas en Tándem , Sedimentos Geológicos/química , Antibacterianos/análisisRESUMEN
Water pollution by pathogenic bacteria and organic dyes poses potential health hazards for human and aquatic life. This study aims to explore the potential of bioactive compounds extracted from two microalgae species (Spirogyra and Ocillatoria) for water pollution control. The optimization of the extraction process for bioactive compounds resulted in the highest yield at 25 min for Spirogyra and 30 min for Ocillatotia species. Further, the extracted bioactive compounds were analyzed using Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectroscopy (GC-MS). The bioactive compounds exhibited significant antibacterial activity against gram-positive and gram-negative bacteria. Notably, Spirogyra species exhibited a higher zone of inhibition (19.5-20.7 mm) than Ocillatoria species (17.0-18.0 mm) against both gram-positive and gram-negative bacterial strains. Furthermore, the photocatalytic potential of these bioactive compounds was examined by assessing the photodegradation of methylene blue (MB) and crystal violet (CV) dyes under different light sources. The findings revealed that Spirogyra species exhibited better photocatalytic activity than Ocillatoria species for MB and CV. For MB, 89.75 %, 77.82 % and 63.54 % were photodegraded when exposed to UV light, sunlight and visible light using Spirogyra extract, compared to 84.90 %, 74.70 % and 58.30 % by Ocillatoria extract. Regarding CV, Spirogyra extract achieved photodegradation efficiency of 88.94 %, 76.59 % and 64.50 % under UV light, sunlight and visible light, higher than 83.60 %, 73.60 % and 57.70 % by Ocillatoria extract. Both Spirogyra and Ocillatoria species demonstrated the best performance for dye photodegradation under UV irradiation, demonstrating great potential for nature-based water treatment.
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Microalgas , Spirogyra , Humanos , Antibacterianos/farmacología , Bacterias Gramnegativas , Bacterias Grampositivas , Azul de Metileno/química , Colorantes , CatálisisRESUMEN
The adsorption process of inorganic arsenic (As) plays an important role in its mobility, bioavailability, and toxicity in the river environment. In this work, the adsorption of dissolved arsenite (As(III)) and arsenate (As(V)) by microplastics (MPs) pellets (polystyrene (PS) and low-density polyethylene (LDPE)), river sediment, and their mixture were investigated to assess the adsorption affinities and mechanism. The adsorption kinetics showed slow and mild rising zones from the natural behavior of the chemical adsorption. The results indicated that both MP characteristics and water properties played a significant role in the adsorption behavior of inorganic As species. The As adsorption equilibrium was modeled well by both Langmuir and Freundlich isotherms and partly fitted with the Sips model suggesting that both mono-layer and multi-layer adsorption occurred during adsorption The spontaneous adsorption process for both As(III) and As(V) was evidenced by the adsorption thermodynamics. The maximum adsorption capacities of As(III) and As(V) reached 143.3 mg/kg and 109.8 mg/kg on PS in deionized water, which were higher than those on sediment-PS mixture (119.3 mg/kg, 99.2 mg/kg), which were all lower than on sediment alone (263.3 mg/kg, 398.7 mg/kg). The Fourier transform infrared spectroscopy analysis identified that As(III) and As(V) interaction with sediment surface functional groups was the main adsorption mechanism from surface complexation and coordination. Two functional groups of polystyrene (-NH2, -OH) were mainly involved in the adsorption of inorganic As species on PS, while -COO- and -OH functional groups contributed to the adsorption mechanism of inorganic As species on LDPE. The findings provide valuable insight on the adsorption behavior and mechanisms of As(III) and As(V) in river systems in the presence of MPs particles. Both PS and LDPE were shown to be less effective than river sediment in the adsorption of As species from water, which provides a different perspective in understanding the scale of MPs impact in pollutant transport in the aquatic environment.
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Arsénico , Arsenicales , Contaminantes Químicos del Agua , Poliestirenos/análisis , Arsénico/análisis , Polietileno , Plásticos/química , Ríos , Adsorción , Contaminantes Químicos del Agua/análisis , Microplásticos/química , Agua/análisisRESUMEN
This work presents an innovative approach to developing a low-carbon and hazard-free cementitious material (EGC) by activating ground granulated blast-furnace slag (GGBS) with electrolytic manganese residue (EMR), which has an excellent heavy metal solidified capacity. Herein, the multi-step leaching was creatively conducted to investigate the solidified morphology of heavy metals in hazardous EMR. CO2 emission per unit strength factor was calculated to quantitatively analyze the low-carbon degree. The results show that the added hazardous EMR rich in sulfate and the dilution effect caused by the decrease in GGBS lessen the final setting time and fluidity. Low-temperature calcination (200 °C) alters the dissolution rate of ettringite and AFm-like phases by changing the sulfate crystal. Excessive acidic EMR consumes more calcium hydroxide and lowers the pH of the EGC system, resulting in weakened GGBS activity. The formation of jouravskite, thaumasite, and henritermierite are AFm-like hydrated lamellated structures, which provides evidence for the immobilization of Mn2+ in EMR. Vast Mn2+ are embedded in the main interlayer of [Ca2Al(OH)6]+ by substituting Al to form AFm-like phase. The lowest 60d unit compressive strength carbon emission of the EGC system containing 20 % calcinated EMR is 0.78 kgâMPa-1âm-3, meaning the substitution barrier is better addressed by adding calcined EMR. This work provides an innovative solution for high value-added and hazard-free utilization for EMR and carbon reduction in the cement industry.
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Phthalic acid esters (PAEs) are known as the most widely used plasticizer as well as one of the ubiquitously distributed emerging pollutants. Biodegradation and bioremediation via application of PAEs-degrading microbes is promising. In this study, a novel marine microbe, Gordonia hongkongensis RL-LY01, was isolated from mangrove sediment showing high di-(2-ethylhexyl) phthalate (DEHP) degradation capacity. Strain RL-LY01 could degrade a wide range of PAEs and the degradation kinetics of DEHP followed the first-order decay model. Meanwhile, good environmental adaptability, preference to alkaline conditions and good tolerance to salinity and metal ions was shown. Further, metabolic pathway of DEHP in strain RL-LY01 was proposed, with di-ethyl phthalate, phthalic acid, benzoic acid and catechol as intermediates. Additionally, one known mono-alkyl phthalate hydrolase gene (mehpH) was identified. Finally, the excellent performance during bioremediation of artificial DEHP-contaminated saline soil and sediment indicated strain RL-LY01 employs great application potential for the bioremediation of PAE-contaminated environments.
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Dietilhexil Ftalato , Ácidos Ftálicos , Biodegradación Ambiental , Suelo , Ésteres , Dibutil FtalatoRESUMEN
Mycolicibacterium phocaicum RL-HY01, a marine bacterial strain with the capability to degrade phthalic acid esters (PAEs), was isolated from Zhanjiang Bay, China. Here, the complete genome sequence of strain RL-HY01 was presented. The genome of strain RL-HY01 contains one circular chromosome of 6,064,759 bp with a G + C content of 66.93 mol%. The genome contains 5681 predicted protein-encoding genes, 57 tRNA genes, and 6 rRNA genes. Genes and gene clusters potentially involved in the metabolism of PAEs were further identified. The genome Mycolicibacterium phocaicum RL-HY01 will be helpful for advancing our understanding of the fate of PAEs in marine ecosystem.
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Ácidos Ftálicos , Ácidos Ftálicos/análisis , Ácidos Ftálicos/metabolismo , Ecosistema , Bahías , Biodegradación Ambiental , Ésteres/análisis , Ésteres/metabolismo , Bacterias/metabolismo , ChinaRESUMEN
In this work, the electrolytic manganese residues (EMR) were used as sulfate activators for fly ash and granulated blast-furnace slag to fabricate highly reactive supplementary cementitious materials (SCMs). The findings promote the implementation of a win-win strategy for carbon reduction and waste resource utilisation. The effects of EMR dosing on the mechanical properties, microstructure and CO2 emission of the EMR-doped cementitious materials are investigated. The results show that low dosing EMR (5 %) produced more ettringite, fostering early strength development. The fly ash-doped mortar strength increases and then decreases with the addition of EMR from 0 to 5 % to 5-20 %. It was found that blast furnace slag contributes less to strength than fly ash. Moreover, the sulfate activation and the micro-aggregate effect compensate for the EMR-induced dilution effect. The significant increase in strength contribution factor and direct strength ratio at each age verifies the sulfate activation of EMR. The lowest EIF90 value of 5.4 kgâMPa-1âm3 was achieved for the fly ash-doped mortar with 5 % EMR, suggesting the synergistic effect between fly ash and EMR optimised the mechanical properties while maintaining lower CO2 emissions.
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Per- and polyfluoroalkyl substances (PFAS), one of the main categories of emerging contaminants, are a family of fluorinated organic compounds of anthropogenic origin. PFAS can endanger the environment and human health because of their wide application in industries, long-term persistence, unique properties, and bioaccumulation potential. This study sought to explain the accumulation of different PFAS in water bodies. In aquatic environments, PFAS concentrations range extensively from <0.03 (groundwater; Melbourne, Australia) to 51,000 ng/L (Groundwater, Sweden). Additionally, bioaccumulation of PFAS in fish and water biota has been stated to range from 0.2 (Burbot, Lake Vättern, Sweden) to 13,900 ng/g (Bluegill samples, U.S.). Recently, studies have focused on PFAS removal from aqueous solutions; one promising technique is advanced oxidation processes (AOPs), including microwaves, ultrasound, ozonation, photocatalysis, UV, electrochemical oxidation, the Fenton process, and hydrogen peroxide-based and sulfate radical-based systems. The removal efficiency of PFAS ranges from 3% (for MW) to 100% for UV/sulfate radical as a hybrid reactor. Therefore, a hybrid reactor can be used to efficiently degrade and remove PFAS. Developing novel, efficient, cost-effective, and sustainable AOPs for PFAS degradation in water treatment systems is a critical area of research.
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Fluorocarburos , Contaminantes Químicos del Agua , Animales , Humanos , Contaminantes Químicos del Agua/análisis , Compuestos Orgánicos , Sulfatos , Fluorocarburos/análisisRESUMEN
High-mileage vehicles such as taxis make disproportionately large contributions to urban air pollution due to their accelerated engine deterioration rates and high operation intensities despite their small proportions of the total fleet. Controlling emissions from these high-mileage fleets is thus important for improving urban air quality. This study evaluates the effectiveness of a pilot repair program in reducing emissions from taxis in Hong Kong which account for about 2 % of the total licensed vehicles. The emission factors of a large sample of 684 in-service taxis (including 121 for an emission survey program and 563 for a pilot repair program) were measured on transient chassis dynamometers. The results showed that 63 % of the sampled taxis failed the driving cycle test before the pilot repair program. Most of failed taxis were NO related and 91 % of failed taxis exceeded the emission limits of at least two regulated pollutants simultaneously. After the pilot repair program by replacing catalytic converters and oxygen sensors, the failure rate was significantly reduced to only 7 %. In addition, the fleet average NO, HC and CO emission factors were reduced by 85 %, 82 % and 56 %, respectively. In addition, on-road remote sensing measurements confirmed the real-world emission reductions from the taxis that participated in the pilot repair program. These findings led to the implementation of a large-scale replacement program for all taxis in Hong Kong during 2013-2014, which was estimated to have reduced the total HC, CO and NO emissions by about 420, 2570 and 1000 t per year, respectively (equivalent to 5-8 % emission reductions from the whole road transport sector). Therefore, reducing emissions from the small high-mileage fleets is a highly cost-effective measure to improve urban air quality.
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Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Monitoreo del Ambiente/métodos , Vehículos a Motor , Oxígeno , Emisiones de Vehículos/análisis , Emisiones de Vehículos/prevención & controlRESUMEN
Soil salinization has been recognized as one of the main factors causing the decrease of cultivated land area and global plant productivity. Application of salt tolerant plants and improvement of plant salt tolerance are recognized as the major routes for saline soil restoration and utilization. Sea rice 86 (SR86) is known as a rice cultivar capable of growing in saline soil. Genome sequencing and transcriptome analysis of SR86 have been conducted to explore its salt tolerance mechanisms while the contribution of rhizobacteria is underexplored. In the present study, we examined the rhizosphere bacterial diversity and soil metabolome of SR86 seedlings under different salinity to understand their contribution to plant salt tolerance. We found that salt stress could significantly change rhizobacterial diversity and rhizosphere metabolites. Keystone taxa were identified via co-occurrence analysis and the correlation analysis between keystone taxa and rhizosphere metabolites indicated lipids and their derivatives might play an important role in plant salt tolerance. Further, four plant growth promoting rhizobacteria (PGPR), capable of promoting the salt tolerance of SR86, were isolated and characterized. These findings might provide novel insights into the mechanisms of plant salt tolerance mediated by plant-microbe interaction, and promote the isolation and application of PGPR in the restoration and utilization of saline soil.
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Alphaproteobacteria , Microbiota , Oryza , Metaboloma , Rizosfera , Tolerancia a la Sal , Suelo , Microbiología del SueloRESUMEN
The adsorption of inorganic arsenic (As) plays an important role in the mobility and transport of As in the river environment. In this work, the adsorption and desorption of arsenite [As(III)] and arsenate [As(V)] on river sediment were conducted under different pH, initial As concentrations, river water and sediment composition to assess As adsorption behavior and mechanism. Both adsorption kinetics and equilibrium results showed higher adsorption capacity of sediment for As(V) than As(III). Adsorption of As(III) and As(V) on river sediment was favored in acidic to neutral conditions and on finer sediment particles, while sediment organic matter marginally reduced adsorption capacity. In addition, higher adsorption affinity of As(III) and As(V) in river sediment was observed in deionised water than in river water. For the release process, the desorption of both As(III) and As(V) followed nonlinear kinetic models well, showing higher amount of As(III) release from sediment than As(V). Adsorption isotherm was well described by both Langmuir and Freundlich models, demonstrating higher maximum adsorption capacity of As(V) at 298.7 mg/kg than As(III) at 263.3 mg/kg in deionised water, and higher maximum adsorption capacity of As(III) of 234.3 mg/kg than As(V) of 206.2 mg/kg in river water. The XRD showed the changes in the peaks of mineral groups of sediment whilst FTIR results revealed the changes related to surface functional groups before and after adsorption, indicating that Fe-O/Fe-OH, Si(Al)-O, hydroxyl and carboxyl functional groups were predominantly involved in As(III) and As(V) adsorption on sediment surface. XPS analysis evidenced the transformation between these As species in river sediment after adsorption, whilst SEM-EDS revealed higher amount of As(V) in river sediment than As(III) due to the lower signal of Al.