RESUMO
Cadmium (Cd)-contamination impairs biological nitrogen fixation in legumes (BNF), threatening global food security. Innovative strategies to enhance BNF and improve plant resistance to Cd are therefore crucial. This study investigates the effects of graphitic carbon nitride nanosheets (g-C3N4 NSs) on soybean (Glycine max L.) in Cd contaminated soil, focusing on Cd distribution, chemical forms and nitrogen (N) fixation. Soybean plants were treated with 100 mg kg-1 g-C3N4 NSs, with or without 10 mg kg-1 Cd for 4 weeks. Soil addition of g-C3N4 NSs alleviated Cd toxicity and promote soybean growth via scavenging Cd-mediated oxidative stress and improving photosynthesis. Compared to Cd treatment, g-C3N4 NSs increased shoot and root dry weights under Cd toxicity by 49.5% and 63.4%, respectively. g-C3N4 NSs lowered Cd content by 35.7%-54.1%, redistributed Cd subcellularly by increasing its proportion in the cell wall and decreasing it in soluble fractions and organelles, and converted Cd from high-toxicity to low-toxicity forms. Additionally, g-C3N4 NSs improved the soil N cycle, stimulated nodulation, and increased the N-fixing capacity of nodules, thus increasing N content in shoots and roots by 12.4% and 43.2%, respectively. Mechanistic analysis revealed that g-C3N4 NSs mitigated Cd-induced loss of endogenous nitric oxide in nodules, restoring nodule development. This study highlights the potential of g-C3N4 NSs for remediating Cd-contaminated soil, reducing Cd accumulation, and enhancing plant growth and N fixation, offering new insights into the use of carbon nanomaterials for soil improvement and legume productivity under metal(loid)s stress.
RESUMO
Zeolite imidazole frameworks (ZIFs), a class of the metal organic framework, have been extensively studied in environmental applications. However, their environmental fate and potential ecological impact on plants remain unknown. Here, we investigated the phytotoxicity, transformation, and bioaccumulation processes of two typical ZIFs (ZIF-8 and ZIF-67) in rice (Oryza sativa L.) under hydroponic conditions. ZIF-8 and ZIF-67 in the concentration of 50 mg/L decreased root and shoot dry weight maximally by 55.2% and 27.5%, 53.5% and 37.5%, respectively. The scanning electron microscopy (SEM) imaging combined with X-ray diffraction (XRD) patterns revealed that ZIFs on the root surface gradually collapsed and transformed into nanosheets with increasing cultivation time. The fluorescein isothiocyanate (FITC) labeled ZIFs were applied to trace the uptake and translocation of ZIFs in rice. The results demonstrated that the transformed ZIFs were mainly distributed in the intercellular spaces of rice root, while they cannot be transported to culms and leaves. Even so, the Co and Zn contents of rice roots and shoots in the ZIFs treated groups were increased by 1145% and 1259%, 145% and 259%, respectively, compared with the control groups. These findings suggested that the phytotoxicity of ZIFs are primarily attributed to the transformed ZIFs and to a less extent, the metal ions and their ligands, and they were internalized by rice root and increased the Co and Zn contents of shoots. This study reported the transformation of ZIFs and their biological effectiveness in rice, highlighting the potential environmental hazards and risks of ZIFs to crop plants.
Assuntos
Bioacumulação , Imidazóis , Oryza , Plântula , Poluentes do Solo , Zeolitas , Oryza/efeitos dos fármacos , Oryza/metabolismo , Imidazóis/toxicidade , Plântula/efeitos dos fármacos , Plântula/metabolismo , Poluentes do Solo/toxicidade , Estruturas MetalorgânicasRESUMO
Cadmium (Cd) pollution poses a serious threat to plant growth and yield. Nanomaterials have shown great application potential for alleviation of Cd toxicity to plants. In this study, we applied graphitic carbon nitride nanosheets (g-C3N4 NSs) for alleviation of Cd-toxicity to soybean (Glycine max L.). The g-C3N4 NSs supplementation significantly improved plant growth and reduced oxidative damage in the Cd-toxicated soybean seedlings through hydroponic culture. Particularly, the g-C3N4 NSs dynamically regulated the root cell wall (RCW) components by increasing pectin content and modifying its demethylation via enhancing pectin methylesterase (PME) activity, therefore greatly enhanced stronger RCW-Cd retention (up to 82.8%) and reduced Cd migration to the shoot. Additionally, the g-C3N4 NSs reversed the Cd-induced chlorosis, increased photosynthetic efficiency because of enhancement in Fv/Fm ration, Y(II) and sugars content. These results provide new insights into the alleviation of Cd toxicity to plants by g-C3N4 NSs, and shed light on the application of low-cost and environmental-friendly carbon-based NMs for alleviating heavy metal toxicity to plants.
Assuntos
Cádmio , Grafite , Cádmio/toxicidade , Glycine max , Compostos de Nitrogênio , Raízes de PlantasRESUMO
Rhizosphere microbiota are an important factor impacting plant uptake of pollutants. However, little is known about how microbial nitrogen (N) transformation in the rhizosphere affects the uptake and accumulation of antibiotics in plants. Here, we determined recruitment of N transformation functional bacteria upon ciprofloxacin (CIP) exposure, by comparing differences in assembly processes of both rhizospheric bacterial communities and N transformation between two choysum (Brassica parachinensis) varieties differing in CIP accumulation. The low accumulation variety (LAV) of CIP recruited more host bacteria (e.g., Nitrospiria and Nitrolancea) carrying nitrification genes (mainly nxrA) but fewer host bacteria carrying denitrification genes, especially narG, relative to the high accumulation variety (HAV) of CIP. The nxrA and narG abundance in the LAV rhizosphere were, respectively, 1.6-7.8 fold higher and 1.4-3.4 fold lower than those in the HAV rhizosphere. Considering that nitrate can decrease CIP uptake into choysum through competing for the proton motive force and energy, such specific bacteria recruitment in LAV favored the production and utilization of nitrate in its rhizosphere, thus limiting its CIP accumulation with 1.6-2.4 fold lower than the HAV. The findings give insight into the mechanism underlying low pollutant accumulation, filling the knowledge gap regarding the profound effects of rhizosphere microflora and N transformation processes on antibiotic accumulation in crops.
Assuntos
Brassica , Ciprofloxacina , Rizosfera , Nitratos , Nitrogênio/análise , Antibacterianos , Bactérias/genética , Plantas , Solo , Microbiologia do SoloRESUMO
Wetlands are carbon pools for terrestrial ecosystems and play an important role in the global carbon cycle. The Nanhui tidal flat is located at the Yangtze River estuary and has been disturbed by various human activities. However, the effect of human activities on the carbon accumulation capability and carbon storage of wetlands in the Nanhui tidal flat is poorly understood. In this study, the annual carbon accumulation capability and carbon storage of three types of Spartina alterniflora Loisel. wetlands in the Nanhui tidal flat, which were defined as a natural wetland, silt-promoting wetland, and artificial restored wetland, were evaluated by analyzing the plant carbon fixation capability, soil carbon emissions, and soil organic carbon (SOC) density. The results showed that the three wetlands all had a carbon sink effect and the natural wetland, artificial restored wetland, and silt-promoting wetland annually accumulated 7.94, 7.14, and 6.33 kg m-2 CO2, respectively. The existing SOC density in the subsurface soil (0-40 cm) in the natural wetland, silt-promoting wetland, and artificial restored wetland was 23.26, 17.95, and 12.21 kg m-2 CO2, respectively. The natural wetland, with no human disturbance, had a longer duration of waterlogging and greater tidal nutrition inputs than the other wetlands, resulting in a higher plant biomass and lower soil respiration (SR). It therefore had the strongest carbon accumulation capability and highest SOC storage.
Assuntos
Estuários , Áreas Alagadas , Carbono/análise , China , Ecossistema , Monitoramento Ambiental , Rios , SoloRESUMO
Point bar areas around lakes can provide ecological service functions. For example, plants growing on point bars absorb and remove nutrients from the soil and water. However, if the point-bar plants are unregulated, in the fall and winter, plant debris will decompose, releasing nutrients that then enter the water body and cause eutrophication. Therefore, any harvesting should be managed. But how to harvest plants and how often to harvest them, and there is little research on these. In this study, the point bar at Qingcaosha Reservoir was used to study the effects of three plant harvesting modes (M1: unharvested; M2: one harvest in the fall; and M3: one harvest in summer and one in the fall) on the removal of nitrogen (N) from point-bar soil. The largest amount of N was removed by the plants when the M3 mode was used (26.93â¯g/m2). However, the M2 mode removed the most N from the soil during the plant growth season (81.62â¯g/m2), which implied that the nitrification and denitrification effects of soil microorganisms make the largest contribution to N removal from this point-bar soil. The nitrification and denitrification activity of microorganisms was higher for M2 than for M1 and M3 in the following year. Additionally, summer harvesting (M3) had a negative effect on nitrification efficiency in the current season because anaerobic bacteria in the soil significantly increased and nitrifying bacteria significantly decreased after harvesting. However, after a period of recovery, the number of microbial nitrifiers increased again and nitrification activity rose in the following year. The reduction in oxygen supply after harvesting may be the main reason for low nitrification in the current season, but it was beneficial to nitrification and denitrification in the following year because there was luxuriant plant growth. Therefore, when considering both the current season and the following year, harvesting should not be too frequent and one harvest in the fall (M2) led to the largest removal of N from the soil.
Assuntos
Lagos , Nitrogênio , Desnitrificação , Nitrificação , SoloRESUMO
Wetlands are important carbon (C) pools for terrestrial ecosystems, and C stored in different types of wetlands accounts for about 30% of total terrestrial C. As one of the most important ecological barriers in Shanghai, with functions of climate regulation, interception, and purification, and as a C sink, the Jiuduansha wetland has received research attention. However, little research has been done on the spatial differences in amount of average annual net C accumulation and C storage of each shoal: Jiangya Nansha, Shangsha, and Zhongxiasha. In this study, plant biomass, plant organic C, soil respiration, soil organic C content, and soil bulk density of different vegetation zones in the three shoals were analyzed to determine the spatial variability of annual net C accumulation capability and soil organic C storage of the Jiuduansha wetland. The results showed that the Zhongxiasha shoal played the most important role as a C sink, and it accumulated 77,839.44 t organic C per year. Regarding the annual C accumulation capacity per unit area, the Phragmites communis zone was higher than for all other vegetation zones, indicating that P. communis had the greatest C accumulation capacity. 7835.38 t, 46,827.41 t, and 173,623.1 t of organic C were stored in the Jiangya Nansha, Shangsha, and Zhongxiasha shoals, respectively. The C storage in soil was closely related to annual C accumulation, and there were two main reasons for the difference of spatial pattern of annual C accumulation: biomass and properties of plants and the properties of tidal water.
Assuntos
Carbono/análise , Monitoramento Ambiental/métodos , Poaceae/química , Rios/química , Solo/química , Biomassa , China , Ecossistema , Estuários , Plantas , Áreas AlagadasRESUMO
The Lon protease is highly evolutionarily conserved. However, little is known about Lon in the context of gut microbial communities. A gene encoding a Lon-like protease (Lon-like-Ms) was identified and characterized from Methanobrevibacter smithii, the predominant archaeon in the human gut ecosystem. Phylogenetic and sequence analyses showed that Lon-like-Ms and its homologs are newly identified members of the Lon family. A recombinant form of the enzyme was purified by affinity chromatography, and its catalytic properties were examined. Recombinant Lon-like-Ms exhibited ATPase activity and cleavage activity toward fluorogenic peptides and casein. The peptidase activity of Lon-like-Ms relied strictly on Mg(2+) (or other divalent cations) and ATP. These results highlight a new type of Lon-like protease that differs from its bacterial counterpart.
Assuntos
Trifosfato de Adenosina/metabolismo , Methanobrevibacter/enzimologia , Methanobrevibacter/genética , Protease La/genética , Protease La/metabolismo , Adenosina Trifosfatases/metabolismo , Sequência de Aminoácidos , Cromatografia de Afinidade , Análise por Conglomerados , Coenzimas/metabolismo , DNA Arqueal/química , DNA Arqueal/genética , Microbioma Gastrointestinal , Humanos , Magnésio/metabolismo , Methanobrevibacter/isolamento & purificação , Microbiota , Dados de Sequência Molecular , Filogenia , Protease La/isolamento & purificação , Análise de Sequência de DNA , Especificidade por SubstratoRESUMO
Graphitic carbon nitride (g-C3N4) is a promising candidate for heavy metal remediation, primarily composed of carbon (C) and nitrogen (N). It has been demonstrated that g-C3N4 adjusts rhizosphere physicochemical conditions, especially N conditions, alleviating the absorption and accumulation of Cadmium (Cd) by soybeans. However, the mechanisms by which g-C3N4 induces N alterations to mitigates plant uptake of Cd remain unclear. This study investigated the impact of g-C3N4-mediated changes in N conditions on the accumulation of Cd by soybeans using pot experiments. It also explored the microbiological mechanisms underlying alterations in soybean rhizospheric N cycling induced by g-C3N4. It was found that g-C3N4 significantly increased N content in the soybean rhizosphere (p < 0.05), particularly in terms of available nitrogen (AN) of nitrate and ammonium. Plants absorbed more ammonium nitrogen (NH4âº-N), the content of which in the roots showed a significant negative correlation with Cd concentration in plant (p < 0.05). Additionally, g-C3N4 significantly affected rhizospheric functional genes associated with N cycling (p < 0.05) by increasing the ratio of the N-fixation functional gene nifH and decreasing the ratios of functional genes amoA and nxrA involved in nitrification. This enhances soybean's N-fixing potential and suppresses denitrification potential in the rhizosphere, preserving NH4âº-N. Niastella, Flavisolibacter, Opitutus and Pirellula may play a crucial role in the N fixation and preservation process. In summary, the utilization of g-C3N4 offers a novel approach to ensure safe crop production in Cd-contaminated soils. The results of this study provide valuable data and a theoretical foundation for the remediation of Cd polluted soils.
Assuntos
Cádmio , Glycine max , Grafite , Nitrogênio , Rizosfera , Glycine max/metabolismo , Glycine max/efeitos dos fármacos , Glycine max/microbiologia , Cádmio/toxicidade , Cádmio/metabolismo , Nitrogênio/metabolismo , Poluentes do Solo/metabolismo , Poluentes do Solo/toxicidade , Compostos de Nitrogênio/metabolismo , Raízes de Plantas/metabolismo , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/microbiologiaRESUMO
In 2016, the Yangtze River Protection Strategy was proposed and a series of measures were applied to restore the health and function of the Yangtze River ecosystem. However, the impact of these measures on the carbon (C) sink capacity of the Yangtze River estuary wetlands has not been exhaustively studied. In this work, the effects of these measures on the C sink capacity of Yangtze River estuary wetlands were examined through the long-term monitoring of C fluxes, soil respiration, plant growth and water quality. The C flux of the Yangtze River estuary wetlands has become increasingly negative after the implementation of these measures, mainly owing to reduction in soil CO2 emission. The decrease in the chemical fertilizer release and returning farmland to wetland had led to the improvement of water quality in the estuary area, which further reduced soil heterotrophic microbial activity, and ultimately decreasing soil CO2 emissions of estuary wetlands.
RESUMO
The inland and estuary wetlands that characterized by different natural environment perform distinctly in soil carbon (C) sink. It was deemed that estuary wetland has a higher organic C accumulation rate than inland wetland, due to its higher primary production and tidal organics input, thus having higher organic C sink capacity. While from CO2 budge in view, whether does the large organic input from tide restrict CO2 sequestration capacity of estuary wetland has not been discussed comparing with inland wetland. In this study, inland and estuary wetlands were selected to study the potential of CO2 sequestration capacity. It was found that inland wetland had most of soil organic carbon (SOC) derived from plant C, which brought remarkable organic C content and nourished higher microbial biomass, dehydrogenase, and ß_glucosidase than estuary wetland. The estuary wetland instead accumulated less SOC, a considerable proportion of which came from tidal waters, therefore supporting lower microbial biomass and enzyme activities than that in inland wetland. However, estuary wetland was evaluated having higher capability in SOC mineralization than inland wetland in consideration of soil respiration (SR) and SR quotient. It was concluded that tidal organic C accelerated the SOC mineralization in estuarine wetland, thus weakening the CO2 sequestration. These results implied the importance of pollution control for reservation CO2 sink function in estuarine wetland.
Assuntos
Dióxido de Carbono , Áreas Alagadas , Carbono/análise , Solo , Biomassa , China , Sequestro de CarbonoRESUMO
Estuarine wetlands with high organic carbon (OC) accumulation rates due to their high plant biomass and interception of tide-derived OC are generally considered as large CO2 sinks. However, our previous study found that tidal OC input seems to stimulate soil CO2 emissions, potentially weakening CO2 sequestration in estuarine wetlands. To further verify this phenomenon, we first established a structural equation model, which confirmed a positive correlation between tidal OC input and soil organic carbon (SOC) and soil respiration. We then performed trace analysis to determine the stability of SOC derived from different sources and its effect on soil CO2 emissions by analyzing the input and retention of OC derived from tides and plants in the Yangtze Estuary wetlands. From upstream to downstream, as tidal OC input decreased, the relative retention ratio of the tidal OC in wetland soil increased from 1.259 to 2.148, whereas the relative retention ratio of plant OC in the soil decreased from 61.5% to 14.8%. Our findings indicated that the degradability of tidal OC was higher upstream than that downstream, but both inhibited plant OC degradation, thus providing an important reason for the higher CO2 emissions upstream of wetlands (with higher tidal OC input). In addition, the primarily contributor to CO2 (δ13) emissions' transforming from plant SOC (81.35%) to tidal SOC (91.18%) was an increase in organic matter input from the tide in a microcosm system. Consequently, a higher CO2 output than CO2 input (plant OC) due to the ready degradation of tidal OC consequently weakens the CO2 sequestration capacity of the estuarine wetlands. This phenomenon is cause for concern regarding the CO2 sink function of estuarine wetlands intercepting large amounts of organic matter.
Assuntos
Carbono , Áreas Alagadas , Carbono/análise , Dióxido de Carbono , Solo/química , Biomassa , Plantas , Sequestro de Carbono , ChinaRESUMO
Cadmium (Cd) contamination has led to various harmful impacts on soil microbial ecosystem, agricultural crops, and thus human health. Nanomaterials are promising candidates for reducing the accumulation of heavy metals in plants. In this study, graphitic carbon nitride (g-C3N4), a two-dimensional polymeric nanomaterial, was applied for ameliorating Cd phytotoxicity to soybean (Glycine max (L.) Merr.). Its impacts on rhizosphere variables, microorganisms, and metabolism were examined. It was found that g-C3N4 increased carbon/nitrogen/phosphorus (C/N/P) content, especially when N contents were averagely 4.2 times higher in the g-C3N4-treated groups. g-C3N4 significantly induced alterations in microbial community structures (P < 0.05). The abundance of the probiotics class Nitrososphaeria was enriched (on average 70% higher in the g-C3N4-treated groups) as was Actinobacteria (226% higher in the g-C3N4 group than in the CK group). At the genus level, g-C3N4 recruited more Bradyrhizobium (122% higher) in the Cd + g-C3N4 group than in the Cd group and more Sphingomonas (on average 24% higher) in the g-C3N4-treated groups. The changes of microbial clusters demonstrated the potential of g-C3N4 to shape microbial functions, promote plant growth, and enhance Cd resistance, despite observing less pronounced modifications in microbial communities in Cd-contaminated soil compared to Cd-free soil. Moreover, abundance of functional genes related to C/N/P transformation was more significantly promoted by g-C3N4 in Cd-contaminated soil (increased by 146%) than in Cd-free one (increased by 32.8%). Therefore, g-C3N4 facilitated enhanced microbial survival and adaptation through the amplification of functional genes. These results validated the alleviation of g-C3N4 on the microbial communities in the soybean rhizosphere and shed a new light on the application of environmental-friendly nanomaterials for secure production of the crop under soil Cd exposure.
Assuntos
Cádmio , Glycine max , Grafite , Microbiota , Compostos de Nitrogênio , Rizosfera , Cádmio/toxicidade , Glycine max/efeitos dos fármacos , Glycine max/crescimento & desenvolvimento , Glycine max/microbiologia , Microbiologia do Solo , Solo/química , Grafite/farmacologia , Compostos de Nitrogênio/farmacologia , Microbiota/efeitos dos fármacosRESUMO
Fusarium wilt [Fusarium oxysporum (Sch1.) f.sp. cucumerinum Owen.] is a major soil-borne disease of cucumber worldwide, and can cause huge yield losses. Biological control of Fusarium wilt of cucumber has received considerable attention. Many bacteria, particularly actinomycetes, are known to produce secondary metabolites synthesized by Polyketide synthases (PKSs) with a diverse range of biological activities. Ketosynthase (KS) gene diversity was analyzed in samples which were collected from rhizosphere soil of both diseased cucumber and healthy cucumber in Dalian, China. The phylogenetic analysis amino acid (AA) sequences indicated that the KS genes in the rhizosphere soil samples were clustered into diverse seven clades, including Sorangium cellulosum, Anabaena variabilis, Nostoc punctiforme, Xanthobacter autotrophicus, Streptomyces, myxobacteria and uncultured bacteria. Among seven major clades in the phylogenetic tree, two clades were peculiar to rhizosphere soil of diseased cucumber and one was peculiar to healthy cucumber. Among the 182 cloned KS genes, 147 KS genes were clustered with the uncultured bacteria group. Most of the KS genes showed about 80% similarity at the AA level to sequences known in GenBank. These results revealed the great diversity and novelty of KS genes in rhizosphere soil of cucumber.
Assuntos
Cucumis sativus/microbiologia , Policetídeo Sintases/genética , Rizosfera , Microbiologia do Solo , Solo/análise , Bactérias/enzimologia , Bactérias/genética , DNA Bacteriano/genética , Genes Bacterianos , Filogenia , Análise de Sequência de DNARESUMO
Polyfluoroalkyl and perfluoroalkyl chemicals (PFCs) widely used in lubricants, surfactant, textiles, paper coatings, cosmetics, and fire-fighting foams can release a large deal of organics contaminants into wastewater and pose great risks to the health of humans and eco-environments. Although advanced oxidation processes can effectively deconstruct various organic contaminants via reactive radicals, the stable structure of PFCs makes it difficult to be degraded. Here, we confirm that electrochemical oxidation process coupled with peroxymonosulfate (PMS) reaction can efficiently destroy stable structure of PFCs via electron transfer and meanwhile completely degrade PFCs via generated active radicals. We further studies via capturing and scavenging radicals, and DFT calculations find that electron hydroxyl radials play a dominant role in degrading PFCs. Based on the calculations of adsorption energy and molecular orbital energy we further demonstrate that many active sites on the surface of Ti4O7 (1 0 4) plane can rapidly take part in electrochemical reaction for generating radials and removing organic contaminants. These results give a promising insight towards high-effective and deep degradation of PFCs via electrochemical reaction coupled with advanced oxidation processes, as well as providing guidance and technical support for the remove of multiple organic contaminants.
Assuntos
Ácidos Alcanossulfônicos , Fluorocarbonos , Transporte de Elétrons , Elétrons , HumanosRESUMO
The electrochemical oxidation method is a promising technology for the degradation of perfluorooctane sulfonate (PFOS). However, the elimination processes of PFOS are still unknown, including the electron transfer pathway, key reactive sites, and degradation mechanism. Here, we fabricated diatomite and cerium (Ce) co-modified Sb2O3 (D-Ce/Sb2O3) anode to realize efficient degradation of PFOS via peroxymonosulfate (PMS) activation. The transferred electron and the generated hydroxyl radical (â¢OH) can high-effectively decompose PFOS. The electron can be rapidly transferred from the highest occupied molecular orbital of the PFOS to the lowest unoccupied molecular orbital of the PMS via the D-Ce/Sb2O3 driven by a potential energy difference under electrochemical process. The active site of Ce-O in the D-Ce/Sb2O3 can greatly reduce the migration distance of the electron and the â¢OH, and thus improving the catalytic activity for degrading various organic micropollutants with high stability. In addition, the electrochemical process shows strong resistance and tolerance to the changing pH, inorganic ions, and organic matter. This study offers insights into the electron transfer pathway and PMS activation mechanism in PFOS removal via electrochemical oxidation, paving the way for its potential application in water purification.
Assuntos
Ácidos Alcanossulfônicos , Poluentes Químicos da Água , Domínio Catalítico , Fluorocarbonos , Peróxidos/química , Água , Poluentes Químicos da Água/químicaRESUMO
Perfluorooctane sulfonate (PFOS), normally present in groundwater and surface water, is an emerging environmental contaminants, but is extremely difficult to be degraded due to high energy of the C-F bond. Here, an electrocoagulation (EC) technique coupled with peroxymonosulfate (PMS) activation was used to deeply degrade PFOS. Results showed that approximately 100% PFOS was removed from the solution in the monopolar serial (MS) mode within 60 min and achieved a high kinetic rate of 0.074 min-1, which was significantly higher than those of reported studies (Table S3). Energy consumption (2.06 kWh/kg) in the MS mode was significantly lower than that of Al (52.30 kWh/kg) and Zn (213.50 kWh/kg) electrodes, which further confirmed the potential application prospects of EC technique. The quenching experiments, electron spin response (ESR) analysis, and DFT calculations can verify that ·OH was the main radical from the reaction of Fe2+-OH reaction site with PMS. In addition, results from fluorine balance and TOC removal also indicated the complete mineralization and degradation of PFOS in the EC process. Quantum chemical calculations can confirm the PFOS degradation mechanism and key active sites for direct electron transfer and radical attack. After five cycle operations of PFOS degradation, the EC process was still effective in degrading PFOS with a removal efficiency above 98%. Thus, this work provided a novel alternative for the high-effective treatment of PFOS from contaminated environmental water bodies.
Assuntos
Ácidos Alcanossulfônicos , Fluorocarbonos , Poluentes Químicos da Água , Domínio Catalítico , Eletrocoagulação , Fluorocarbonos/análise , Peróxidos , Poluentes Químicos da Água/análiseRESUMO
Four DNA extraction methods namely SDS-hyperhaline method (I), modified SDS-hyperhaline method (II), indirect method (III), alkaline lysis method (IV) were evaluated by comparing DNA yield, spectrophotometric quality, genomic integrity and PCR suitability in this paper. The results showed that high DNA yields were obtained by method I, II and IV. However, higher quality of DNA was gained by method III and IV. Based on the results of the Pulsed-Field Gel Electrophoresis (PFGE), the completeness of DNA extracted by method IV was the best. About 6.0 microg DNA can be recovered from 1.0 g soil by method IV which involved to lysis cell by SDS and to precipitate impurities by adding potassium acetate and magnesium chloride Therefore, it is confirmed that method IV is a novel, reliable and versatile method for large-scale DNA extraction involving less purification steps for various soil samples.
Assuntos
DNA Bacteriano/isolamento & purificação , Eletroforese em Gel de Campo Pulsado/métodos , Microbiologia do Solo , Solo/análise , Reação em Cadeia da Polimerase/métodosRESUMO
Soil organic carbon (SOC) is both a product and a cause of soil development. Previous studies found that less carbon (C) is fixed by Phragmites communis than Spartina alterniflora in the Jiuduansha wetland of the Yangtze River Estuary. However, the P. communis zone presented higher contents of SOC and humus, which was mainly related to lower soil respiration (SR). It is not well known how different plants affect turnover of original SOC in the Jiuduansha wetland, and thus soil development and tidal flat evolution. In this study, in-field surveys and microcosm experiments were conducted to trace turnover of plant C and evaluate dynamics of SOC using stable C isotopic techniques. Spartina alterniflora decayed faster than P. communis, and more of its derived OC was lost through SR and leaching. Although S. alterniflora-derived OC suppressed the degradation of original SOC, it was consumed to a greater extent, making less supplementation to SOC. Phragmites communis-derived OC showed less degradability and accelerated the degradation of original SOC, but was more incorporated into new SOC and finally caused higher increase in SOC, specifically in bare tidal flat soil with poor original SOC. Overall, compared with S. alterniflora, P. communis-derived OC more effectively replaced the unstable original SOC, thereby improving the content and stability of SOC, especially for soil in early-development stages of tidal flats.
Assuntos
Solo , Áreas Alagadas , Carbono , China , Estuários , Poaceae , Rios , Plantas Tolerantes a SalRESUMO
Once rice straw has been bioconverted into biofuels, it is difficult to further biodegrade or decompose the saccharification residue (mainly lignin). Taking into account the pyrolysis characteristics of lignin, in this study the saccharification residue was used as a raw material for the preparation of biochar (biochar-SR), a potential soil amendment. Biochar was prepared directly from rice straw (biochar-O) with a yield of 32.45â¯g/100â¯g rice straw, whereas 30.14â¯g biochar-SR and 30.46â¯g monosaccharides (including 20.46â¯g glucose, 9.11â¯g xylose, and 0.89â¯g arabinose) were obtained from 100â¯g of rice straw. When added to liquid soil extracts as a soil amendment, almost nothing was released from biochar-SR, whereas numerous dissolved solids (about 70â¯mg/L) were released from biochar-O. Adding a mixture of biochar-SR and autotrophic bacteria improved soil total organic carbon 1.8-fold and increased the transcription levels of cbbL and cbbM, which were 4.76â¯×â¯103 and 3.76â¯×â¯105 times those of the initial blank, respectively. By analyzing the soil microbial community, it was clear that the above mixture favored the growth of CO2-fixing bacteria such as Ochrobactrum. Compared with burning rice straw or preparing biochar-O, the preparation of biochar-SR reduced CO2 emissions by 67.53% or 37.13%, respectively. These results demonstrate that biochar-SR has potential applications in reducing the cost of sustainable energy and addressing environmental issues.