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Limited by the types of suitable absorbents as well as the challenges in engineering the nanostructures (e.g., defects, dipoles, and hetero-interface) using state-of-the-art additive manufacturing (AM) techniques, the electromagnetic (EM) wave absorption performance of the current ceramic-based materials is still not satisfying. Moreover, because of the high residual porosity and the possible formation of cracks during sintering or pyrolysis, AM-formed ceramic components may in many cases exhibit low mechanical strength. In this work, semiconductive MoS2 and conductive PyC modified Al2 O3 (MoS2 /PyC-Al2 O3 ) ceramic-based structural EM metamaterials are developed by innovatively harnessing AM, precursor infiltration and pyrolysis (PIP), and hydrothermal methods. Three different meta-structures are successfully created, and the ceramic-based nanocomposite benefit from its optimization of EM parameters. Ultra-broad effective absorption bandwidth (EAB) of 35 GHz is achieved by establishment of multi-loss mechanism via nanostructure engineering and fabrication of meta-structures via AM. Due to the strengthening by the PyC phase, the bending strength of the resulting ceramics can reach ≈327 MPa, which is the highest value measured on 3D-printed ceramics of this type that has been reported so far. For the first time, the positive effect deriving from the engineering of the microscopic nano/microstructure and of the macroscopic meta-structure of the absorber on the permittivity and EM absorption performance is proposed. Integration of outstanding mechanical strength and ultra-broad EAB is innovatively realized through a multi-scale design route. This work provides new insights for the design of advanced ceramic-based metamaterials with outstanding performance under extreme environment.
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The prevention of fungal proliferation in postharvest grains is critical for maintaining grain quality and reducing mycotoxin contamination. Fumigation with natural gaseous fungicides is a promising and sustainable approach to protect grains from fungal spoilage. In this study, the antifungal activities of (E)-2-alkenals (C5-C10) on Aspergillus flavus were tested in the vapor phase, and (E)-2-heptenal showed the highest antifungal activity against A. flavus. (E)-2-Heptenal completely inhibited A. flavus growth at 0.0125 µL/mL and 0.2 µL/mL in the vapor phase and liquid contact, respectively. (E)-2-Heptenal can disrupt the plasma membrane integrity of A. flavus via leakage of intracellular electrolytes. Scanning electron microscopy indicated that the mycelial morphology of A. flavus was remarkably affected by (E)-2-heptenal. Metabolomic analyses indicated that 49 metabolites were significantly differentially expressed in A. flavus mycelia exposed to 0.2 µL/mL (E)-2-heptenal; these metabolites were mainly involved in galactose metabolism, starch and sucrose metabolism, the phosphotransferase system, and ATP-binding cassette transporters. ATP production was reduced in (E)-2-heptenal-treated A. flavus, and Janus Green B staining showed reduced cytochrome c oxidase activity. (E)-2-Heptenal treatment induced oxidative stress in A. flavus mycelia with an accumulation of superoxide anions and hydrogen peroxide and increased activities of superoxide dismutase and catalase. Simulated storage experiments showed that fumigation with 400 µL/L of (E)-2-heptenal vapor could completely inhibit A. flavus growth in wheat grains with 20% moisture; this demonstrates its potential use in preventing grain spoilage. This study provides valuable insights into understanding the antifungal effects of (E)-2-heptenal on A. flavus. KEY POINTS : ⢠(E)-2-Heptenal vapor showed the highest antifungal activity against A. flavus among (C5-C10) (E)-2-alkenals. ⢠The antifungal effects of (E)-2-heptenal against A. flavus were determined. ⢠The antifungal actions of (E)-2-heptenal on A. flavus were revealed by metabolomics and biochemical analyses.
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Antifúngicos , Aspergillus flavus , Antifúngicos/farmacologia , Antifúngicos/metabolismo , Aldeídos/metabolismo , MetabolômicaRESUMO
Fungal spoilage of postharvest grains poses serious problems with respect to food safety, human health, and the economic value of grains. The protection of cereal grains from deleterious fungi is a critical aim in postharvest grain management. Considering the bulk volume of grain piles in warehouses or bins and food safety, fumigation with natural gaseous fungicides is a promising strategy to control fungal contamination on postharvest grains. Increasing research has focused on the antifungal properties of biogenic volatiles. This review summarizes the literature related to the effects of biogenic volatiles from microbes and plants on spoilage fungi on postharvest grains and highlights the underlying antifungal mechanisms. Key areas for additional research on fumigation with biogenic volatiles in postharvest grains are noted. The research described in this review supports the protective effects of biogenic volatiles against grain spoilage by fungi, providing a basis for their expanded application in the management of postharvest grains.
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Fungos , Fungicidas Industriais , Humanos , Antifúngicos/farmacologia , Fungicidas Industriais/farmacologia , Grão Comestível/microbiologiaRESUMO
Dissolved organic matter (DOM) controls the bioavailability and toxicity of heavy metals in aquatic environments. The observation of decreased conditional binding constants with increasing DOM concentration is not well documented, which may result in significant uncertainties in heavy metal behavior modeling and risk assessment. We used eight low molecular weight organic acids (LMOC) with representative structures to simulate DOM molecules. The interactions between LMOC molecules resulted in the decreased Cu(II)-LMOC binding with increasing LMOC concentrations, but higher pH values than theoretical calculation after mixing LMOC solutions of different pHs. We thus proposed homoconjugation between LMOC molecules through negative charge-assisted H-bond ((-)CAHB). A mathematic model was developed to describe Cu(II)-LMOC complexation ( KC) and LMOC homoconjugation ( KLHL). The increased competition of LMOC homoconjugation over Cu(II)-LMOC complexation, as suggested by the increased ratios of KLHL/ KC, resulted in the apparently decreased Cu(II)-LMOC binding with the increased LMOC concentration. Similar concentration-dependent binding was also observed for DOM. With the identified homoconjugation between DOM molecules, some of the literature data with concentration-dependent behavior may be re-evaluated. This is the first work that quantitatively identified homoconjugation among organic molecules. Both the modeling concepts and results provide useful information in investigating the environmental roles of DOM in mediating metal bioavailability and transport.
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Metais Pesados , Animais , Peso Molecular , Compostos OrgânicosRESUMO
Bacterial biofilm formation on membrane surfaces remains a serious challenge in water treatment systems. The impact of low voltages on microbial attachment to electrically conducting ultrafiltration membranes was investigated using a direct observation cross-flow membrane system mounted on a fluorescence microscope. Escherichia coli and microparticle deposition and detachment rates were measured as a function of the applied electrical potential to the membrane surface. Selecting bacteria and particles with low surface charge minimized electrostatic interactions between the bacteria and charged membrane surface. Application of an electrical potential had a significant impact on the detachment of live bacteria in comparison to dead bacteria and particles. Image analysis indicated that when a potential of 1.5 V was applied to the membrane/counter electrode pair, the percent of dead bacteria was 32±2.1 and 67±3.6% when the membrane was used as a cathode or anode, respectively, while at a potential of 1 V, 92±2.4% were alive. The application of low electrical potentials resulted in the production of low (µM) concentrations of hydrogen peroxide (HP) through the electroreduction of oxygen. The electrochemically produced HP reduced microbial cell viability and increased cellular permeability. Exposure to low concentrations of electrochemically produced HP on the membrane surface prevents bacterial attachment, thus ensuring biofilm-free conditions during membrane filtration operations.
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Aderência Bacteriana , Condutividade Elétrica , Eletroquímica/métodos , Membranas Artificiais , Biofilmes , Permeabilidade da Membrana Celular , Escherichia coli/fisiologia , Filtração , Cinética , Viabilidade Microbiana , Microscopia Eletrônica de Varredura , Eletricidade EstáticaRESUMO
The stability of Zn-biochar composites is determined by environmental factors, including the aging processes. This paper focused on the ecotoxicological evaluation of Zn-biochar (Zn-BC) composites subjected to chemical aging. Pristine biochars and composites produced at 500 or 700 °C were incubated at 60 and 90 °C for six months. All biochars were characterized in terms of their physicochemical (elemental composition, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and porous structure), ecotoxicological properties (tested with Folsomia candida and Aliivibrio fischeri) and contaminant content (polycyclic aromatic hydrocarbons (PAH), heavy metals (HM) and environmentally persistent free radicals (EPFR)). An increase in the number of surface oxygen functional groups and increased hydrophilicity and polarity of all Zn-BC composites were observed due to oxidation during aging. It was also found that Zn-BC aging at 90 °C resulted in a 28-30% decrease in solvent-extractable PAHs (Æ©16 Ctot PAHs) compared to nonaged composites. The aging process at both temperatures also caused a 104 fold reduction in EPFRs in Zn-BC composites produced at 500 °C. The changes in the physicochemical properties of Zn-BC composites after chemical aging at 90 °C (such as pH and HM content) caused an increase in the toxicity of the composites to Folsomia candida (reproduction inhibition from 19 to 24%) and Aliivibrio fischeri (luminescence inhibition from 96 to 99%). The aging of composites for a long time may increase the adverse environmental impact of BC-Zn composites due to changes in physicochemical properties (itself and its interactions with pollutants) and the release of Zn from the composite.
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Artrópodes , Metais Pesados , Hidrocarbonetos Policíclicos Aromáticos , Animais , Zinco/toxicidade , Carvão Vegetal/química , Metais Pesados/farmacologia , Hidrocarbonetos Policíclicos Aromáticos/toxicidadeRESUMO
Using magnesium-biochar composites (Mg-BC) in adsorption allows for the efficient and economically relevant removal of phosphate (PO43-) from water and wastewater. Applying Mg-BC for pollutant removal requires evaluating the adsorption capacity of composites and their ecotoxicological properties. Investigating the composite aging during the application of these composites into the soil is also essential. In the present study, nonaged and aged (at 60 or 90 °C) Mg-BC composites were investigated in the context of pyrolysis temperature (500 or 700 °C). All analyzed biochars were examined by Fourier transform infrared spectroscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and surface area. The content of polycyclic aromatic hydrocarbons (PAHs) (bioavailable Cfree and organic solvent-extractable Ctot), heavy metals (HMs), and environmentally persistent free radicals (EPFRs) were determined. Ecotoxicity was evaluated using tests with Folsomia candida and Allivibrio fischeri. The dependence of adsorption on pyrolysis temperature and composite aging time was observed. Changes in physicochemical properties occurring as a result of aging reduced the adsorption of PO43- on Mg-BC composites. It was found that nonaged Mg-BC700 was more effective (9.55 mg g -1) in the adsorption of PO43- than Mg-BC500 (5.75 mg g-1). The adsorption capacities of aged composites were from 21 to 61% lower than those of the nonaged composites. Due to aging, the content of Cfree PAHs increased by 3-5 times depending on the pyrolysis temperature. However, aging reduced the Ctot PAHs in all composites from 24 to 35% depending on the pyrolysis temperature. Ecotoxicological evaluation of Mg-BC composites showed increased toxicity after aging to both organisms. The use of aged BC potentially increases the contaminant content and toxicity of Mg-BC composites.
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Magnésio , Hidrocarbonetos Policíclicos Aromáticos , Adsorção , Fosfatos , Carvão Vegetal/química , Hidrocarbonetos Policíclicos Aromáticos/químicaRESUMO
Acid modification has been widely used to modify the structural properties of biochars. However, acid modification led to the large consumption of acid, increased difficulty of waste effluent disposal, and a high application cost. To evaluate the advantages and application potential of biochars prepared under CO2, utilizing pyrolysis to directly modify biochars to improve heavy metal removal efficiency and reduce production cost, would be an important prerequisite for the broad application of biochars. The sorption performance of Pb2+ with CO2-modified biochars was compared with that of HNO3-modified biochar. The elemental compositions and structural properties of biochars were characterized through elemental analysis, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that for biochars produced at 500â, HNO3 modification produced abundant carboxylic groups and -NO2 (asy) and -NO2 (sym) groups, promoting the surface activities and complexing abilities of biochars. The CO2-modified biochars contained abundant carbonate minerals, which could remove Pb2+ by electrostatic ion exchange and coprecipitation or complex. In addition, compared to that of HNO3-modified biochars, CO2-modified biochars had the larger specific surface area and better microporous structures, which were beneficial to the diffusion of Pb2+ and further promoted surface sorption. CO2 modification increased the maximum Pb2+ sorption capacity of W500CO2 and W700CO2, which were 60.14 mg·g-1 and 71.69 mg·g-1. By contrast, HNO3-modified biochars W500N2-A and W700N2-A showed the lower Pb2+ sorption capacities, which were 42.26 mg·g-1 and 68.3 mg·g-1, respectively. The increasing of the specific surface area and functional groups simultaneously promoted the sorption capacity of CO2-modified biochars. Consequently, the CO2-modified biochar had the advantages of low cost, environmental friendliness, and high heavy metal removal efficiency, which is a modification method worthy of promotion and application.
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Plant volatile organic compounds (VOCs) with antimicrobial activity could potentially be extremely useful fumigants to prevent and control the fungal decay of agricultural products postharvest. In this study, antifungal effects of volatile compounds in essential oils extracted from Origanum vulgare L. against Aspergillus flavus growth were investigated using transcriptomic and biochemical analyses. Carvacrol was identified as the major volatile constituent of the Origanum vulgare L. essential oil, accounting for 66.01 % of the total content. The minimum inhibitory concentrations of carvacrol were 0.071 and 0.18 µL/mL in gas-phase fumigation and liquid contact, respectively. Fumigation with 0.60 µL/mL of carvacrol could completely inhibit A. flavus proliferation in wheat grains with 20 % moisture, showing its potential as a biofumigant. Scanning electron microscopy revealed that carvacrol treatment caused morphological deformation of A. flavus mycelia, and the resulting increased electrolyte leakage indicates damage to the plasma membrane. Confocal laser scanning microscopy confirmed that the carvacrol treatment caused a decrease in mitochondrial membrane potential, reactive oxygen species accumulation, and DNA damage. Transcriptome analysis revealed that differentially expressed genes were mainly associated with fatty acid degradation, autophagy, peroxisomes, the tricarboxylic acid cycle, oxidative phosphorylation, and DNA replication in A. flavus mycelia exposed to carvacrol. Biochemical analyses of hydrogen peroxide and superoxide anion content, and catalase, superoxide dismutase, and glutathione S-transferase activities showed that carvacrol induced oxidative stress in A. flavus, which agreed with the transcriptome results. In summary, this study provides an experimental basis for the use of carvacrol as a promising biofumigant for the prevention of A. flavus contamination during postharvest grain storage.
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Óleos Voláteis , Origanum , Antifúngicos/farmacologia , Antifúngicos/química , Óleos Voláteis/farmacologia , Óleos Voláteis/química , Aspergillus flavus , Origanum/química , Triticum , Monoterpenos/químicaRESUMO
In light of the pressing need to reduce carbon emissions, the biomass power generation industry has gained significant attention and has increasingly become a crucial focus in China. However, there are still considerable gaps in the historical background, status, and prospects of biomass power generation. Herein, the historical and current status of biomass power generation in China are systematically reviewed, with a particular emphasis on supportive policies, environmental impacts, and future projections. By 2022, the newly installed capacity for biomass power generation reached 3.34 MW with a total installed capacity of 41 MW. The power produced from biomass power generation is 182.4 billion kWh in China. The total installed capacity and generated power in 2022 were 1652 and 1139 folds higher than in 2006 when the first biomass generation plant was established. However, disparities in the distribution of biomass resources and power generation were observed. Key drivers of the industry development include tax, finance, and subsidy policies. Under the implementation of the 14th Five-Year Plan for renewable energy development and the goal of carbon neutrality, biomass power generation may achieve great success through more targeted policy support and advanced technologies that reduce air pollutant emissions. If combined with Bioenergy with Carbon Capture and Storage (BECCS) technology, biomass power generation will make its contribution to carbon neutrality in China.
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Biomassa , China , Carbono/análise , Centrais Elétricas , Poluição do Ar/prevenção & controle , Poluição do Ar/estatística & dados numéricos , Poluentes Atmosféricos/análise , Energia RenovávelRESUMO
Biochar (BC) engineering, which has recently gained a lot of interest, allows designing the functional materials. BC modification improves the properties of pristine biochar, especially in terms of adsorption parameters. An interesting type of modification is the introduction of metals into the BC's structure. There is a knowledge gap regarding the effects of modified BC (e.g., BC-Mg, BC-Zn) on organisms. The aim of this study was the ecotoxicological evaluation of BC-Mg and BC-Zn composites, received under diverse conditions from willow or sewage sludge at 500 or 700 °C. The ecotoxicological tests with bacteria Vibrio fischeri (V. fischeri) and invertebrates Folsomia candida (F. candida) were applied to determine the toxicity of BC. The content of toxic substances (e.g., polycyclic aromatic hydrocarbons (PAHs), heavy metals (HMs), environmentally persistent free radicals (EPFRs)) in BC were also determined and compared with ecotoxicological parameters. The ecotoxicity of studied BCs depends on many variables: feedstock type, pyrolysis temperature and the modification type. The Zn and Mg modification reduced (from 28 to 63 %) the total Æ©16 PAHs content in willow-derived BCs while in SL-derived BCs the total Æ©16 PAHs content was even 1.5-3 times higher compared to pristine BCs. The Zn modified willow-derived BCs affected positively on F. candida reproduction but showed inhibition of luminescence V. fischeri. BC-Mg exhibited harmful effect to F. candida. The ecotoxicological assessment carried out sheds light on the potential toxicity of BC-Zn and BC-Mg composites, which are widely used in the removal of heavy metals, pharmaceuticals, dyes from waters and soils.
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Artrópodes , Metais Pesados , Hidrocarbonetos Policíclicos Aromáticos , Salix , Animais , Temperatura , Metais Pesados/toxicidade , Carvão Vegetal/química , Esgotos/química , Aliivibrio fischeriRESUMO
Despite the dynamic progress of BC engineering, there is a lack of knowledge on the toxicity and environmental impact of modified BC. The aim of this study was the ecotoxicological evaluation of BC modified with zinc (Zn) using different methods: impregnation of feedstock with Zn before pyrolysis (PR), impregnation with Zn after pyrolysis (PS) and impregnation with Zn after pyrolysis with an additional calcination step (PST). The ecotoxicological assessment was based on tests with invertebrates (Folsomia candida, Daphnia magna) and bacteria (Aliivibrio fischeri). The post-treated and calcined composites had a higher content of total (Ctot) PAHs (144-276 µg kg-1) than pre-treated BC-Zn (68-157 µg kg-1). All BC-Zn treatments stimulated the reproduction of F. candida at the lowest BC dose (0.5%) by 4-24%. Increasing the biochar dose to 1% and 3% retained the stimulating effect of the pre-modified biochars (from 19 to 41%). Pre-modified BC-Zn reduced the luminescence of A. fischeri from 40% to 80%. Post-treated BCs reduced bacterial luminescence by 99%, but the calcination step limited the toxic effects to the level observed for the control. Post-treated BCs had a toxic effect on D. magna, with EC50 values ranging from 433 to 783 mg L-1. The ecotoxicity of composites depends on modification methods, BC dose and pyrolysis temperature. The application of limiting conditions for HM leaching (i.e., pre-modification, calcination) increased the safety of using Zn-biochar composites.
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Artrópodes , Zinco , Animais , Zinco/toxicidade , Carvão Vegetal/farmacologia , TemperaturaRESUMO
Biochar has high carbon stability and is a good carbon sequestration material. Sludge biochar is rich in inorganic minerals, which would provide enrichment in the preparation process of pyrolysis, affecting its carbon sequestration capacity in practice. In this study, municipal sludge biochar (SZB), pharmaceutical sludge biochar (YCB), and chicken manure biochar (JFB) were prepared under the pyrolysis process at 500, 600, and 700â, respectively, and their aging process in soil for 70-100 years was simulated. The physicochemical properties and the carbon loss calculation of the biochars were determined using elemental analysis, FTIR, XRF, ICP, and XRD. The results demonstrated that the type and mass fraction of endogenous minerals in the biochars determined their carbon loss during pyrolysis. Ca and Mg were the main carbon-protecting minerals, whereas Fe may have reduced the carbon stability of the sludge biochars and therefore increased the carbon loss. For the aging process, the stability of the endogenous carbon in the biochars played a major role in its carbon loss, whereas the endogenous minerals played a supporting role. These findings elucidated the effect of the stability of endogenous carbon and the composition of mineral components on the carbon loss of biochars, which may provide references for soil carbon sequestration using sludge and chicken manure biochar.
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Carbono , Gado , Animais , Esterco , Esgotos , Galinhas , SoloRESUMO
High blood pressure associated with PM2.5 exposure is of great concern, especially for rural residents exposed to high PM2.5 levels. However, the impact of short-term exposure to high PM2.5 on blood pressure (BP) has not been well elucidated. Thus, this study aims to focus on the association between short-term PM2.5 exposure with BP of rural residents and its variation between summer and winter. Our results showed that the summertime PM2.5 exposure concentration was 49.3 ± 20.6 µg/m3, among which, mosquito coil users had 1.5-folds higher PM2.5 exposure than non-mosquito coil users (63.6 ± 21.7 vs 43.0 ± 16.7 µg/m3, p < 0.05). The mean systolic and diastolic BP (SBP and DBP, respectively) of rural participants were 122 ± 18.2 and 76.2 ± 11.2 mmHg in summer, respectively. The PM2.5 exposure, SBP, and DBP in summer were 70.7 µg/m3, 9.0 mmHg, and 2.8 mmHg lower than that in winter, respectively. Furthermore, the correlation between PM2.5 exposure and SBP was stronger in winter than that in summer, possibly due to higher PM2.5 exposure levels in winter. The transition of household energy from solid fuels in winter to clean fuels in summer would be benefit to the decline of PM2.5 exposure as well as BP. Results from this study suggested that the reduction of PM2.5 exposure would have positive effect on human health.
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Poluentes Atmosféricos , Poluição do Ar em Ambientes Fechados , Poluição do Ar , Humanos , Pressão Sanguínea , Poluentes Atmosféricos/análise , Material Particulado/análise , Poluição do Ar/análise , Poluição do Ar em Ambientes Fechados/análise , Exposição Ambiental/análiseRESUMO
Recently, p-nitrophenol (PNP), a common organic environmental pollutant, has been reported to be degraded by biochar. Although the degradation mechanism of PNP by biochar has been explored, the role of biochar-derived dissolved organic matter (BDOM) in PNP degradation remains unclear. Two BDOM samples were prepared in this study, and their PNP degradation performance was analyzed. BDOM5 (prepared at 500 °C) exhibited higher PNP degradation ratio than BDOM7 (prepared at 700 °C). The extent of PNP degradation per unit of BDOM5 and BDOM7 reached 9.54 and 4.19 mg/mg, respectively. Gas chromatography-mass spectrometry (GC-MS) analysis showed that both oxidative and reductive processes contributed to the PNP degradation by BDOM. Compared with BDOM7, the higher PNP removal of BDOM5 was due to the higher electron exchange capacity. Furthermore, hydroxyl radicals (OH) played a critical role in the oxidative degradation process of PNP by BDOM. This study sheds light on the phenomenon of PNP degradation by BDOM and these results may be useful for accurately assessing the environmental impact of biochar application.
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Matéria Orgânica Dissolvida , Poluentes Ambientais , Nitrofenóis , Carvão Vegetal/químicaRESUMO
Biochar has attracted increasing research attention. Various modification methods have been proposed to enhance a certain biochar function. However, these modifications may also result in an unstable structure, additional energy consumption, secondary pollution, and/or extra cost. Balanced consideration of different aspects will ensure the sustainable development of biochar technology. This review first summarizes the most commonly used methods for biochar modification. These methods are categorized according to the purposes of modification, such as surface area enlargement, persistent free radical manipulation, magnetism introduction, and redox potential enhancement. More importantly, a systematic analysis and discussion are provided regarding the balanced consideration of biochar designs, such as the balance between effectiveness and stability, functions and risks, as well as effectiveness and cost. Then, perspectives regarding biochar modification are presented. This review calls for attention that biochar modifications should not be evaluated for their functions only. A balanced design of biochars will ensure both the practicability and the effectiveness of this technology.
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Soil biota can determine plant invasiveness, yet biogeographical comparisons of microbial community composition and function across ranges are rare. We compared interactions between Conyza canadensis, a global plant invader, and arbuscular mycorrhizal (AM) fungi in 17 plant populations in each native and non-native range spanning similar climate and soil fertility gradients. We then grew seedlings in the greenhouse inoculated with AM fungi from the native range. In the field, Conyza plants were larger, more fecund, and associated with a richer community of more closely related AM fungal taxa in the non-native range. Fungal taxa that were more abundant in the non-native range also correlated positively with plant biomass, whereas taxa that were more abundant in the native range appeared parasitic. These patterns persisted when populations from both ranges were grown together in a greenhouse; non-native populations cultured a richer and more diverse AM fungal community and selected AM fungi that appeared to be more mutualistic. Our results provide experimental support for evolution toward enhanced mutualism in non-native ranges. Such novel relationships and the rapid evolution of mutualisms may contribute to the disproportionate abundance and impact of some non-native plant species.
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Micobioma , Micorrizas , Raízes de Plantas , Plantas , Solo , Microbiologia do Solo , SimbioseRESUMO
Migration characteristics of the heavy metals Fe, Zn, Mn, and Ni during the preparation of biochar from municipal sludge were studied, and the optimal pyrolysis temperature for the preparation of biochar was determined based on potential environmental risks. Four heavy metals (Fe, Zn, Mn, and Ni) with high total contents in the biochar were selected to determine their species and content changes under different pyrolysis temperatures using the BCR extraction method. An environmental risk assessment for sludge-based biochar was also carried out using the potential ecological risk index (PERI) and risk assessment code (RAC). The results showed that the volatility of the four metals is ranked as follows:Zn>Mn>Fe>Ni. The distribution and transformation of the four metal species were different, but their migration paths shared similar characteristics. In the pyrolysis stage at low temperatures (<500â), unstable fractions gradually changed into more stable species; under high temperatures (>500â), some of the oxidizable and residual fractions were broken, which transformed into reducible fractions, and other fractions escaped into the atmosphere. In the environmental risk assessment, biochar prepared under high pyrolysis temperatures (>500â) showed lower environmental risks, with the best outcomes at 500â.
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Emission factors (EFs) are crucial for establishing emission inventory and subsequent health risk assessment of pollutants. However, the EFs of environmentally persistent free radicals (EPFRs) in PM2.5 have not been well investigated. We measured EPFRs in PM2.5 from burning of different solid fuels in a traditional stove widely used in rural China and calculated the EFs of EPFRs (EFEPFRs). The characteristics of EPFRs varied greatly with PM2.5 depending on the feedstock, and the EFEPFRs of crop residue, firewood and bitumite was 2.13 ± 1.04, 1.40 ± 0.76 and 1.08 ± 0.39 (1020 spins·kg-1), respectively. The estimated results of EPFRs emission associated with PM2.5 showed that the crop residue was the main contributor to the top four provinces with high EPFRs emissions in China in 2010. A wide range (0.03-4.89 cig·person-1·day-1) of equivalent cigarette number converted by inhaling EPFRs in PM2.5 was observed. Provinces with higher equivalent cigarette number were mainly agricultural provinces, because the rural residents tend to use readily available fuels. Additionally, EPFRs in collected PM2.5 during 2 - month photoaging were more stable in particles with higher organic carbon contents. Our findings provided a new insight into the risk assessment of PM2.5 from different sources by taking EPFRs into consideration.
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Biochar can both adsorb and degrade p-nitrophenol (PNP); however, the PNP degradation mechanism has not been well investigated. We prepared two biochars at pyrolysis temperatures of 500 °C (B500) and 700 °C (B700). Although B500 showed much stronger free radical signals (which are associated with organic degradation, according to previous studies), the apparent PNP degradation was approximately 3 times higher in the B700 system. The degradation increased significantly after the biochars were washed with water. According to a quantitative analysis of the sorption and degradation and two-compartment first-order kinetics modeling of the apparent removal kinetics, sorption occurred mainly in the initial period, whereas degradation continued throughout the removal process. The PNP degradation rate constant depended mainly on the external surface area at a relatively low concentration (200 mg/L) and was controlled by the microporous surface area at a relatively high concentration (800 mg/L). In addition, the apparent degradation did not depend on the biochar particle size. Therefore, PNP degradation may be related to the three-dimensional structure of the biochar in addition to the exposed external surface. The well-developed pore structure, more accessible surface, and larger electron exchange capacity of B700 may promote electron transfer between the biochar and PNP, and thus accelerate PNP degradation. This study demonstrates that various properties of the biochar may contribute to PNP degradation.