Organophosphorus pesticides(OPPs) are a set of toxic persistent organic pollutants(POPs) present in the environment. Recently, biochar-mediated bioremediation has exhibited many advantages over conventional methods fo...Organophosphorus pesticides(OPPs) are a set of toxic persistent organic pollutants(POPs) present in the environment. Recently, biochar-mediated bioremediation has exhibited many advantages over conventional methods for the remediation of pesticide-contaminated soil. In the present study, biochar and nitrogen fertilizer(NH_4NO_3)were employed to remediate OPP-contaminated soil and the greenhouse gas(GHG) emission during 90 days of incubation was investigated. After thermal desorption treatment, the content of organophosphorus pesticides reduced from 175.61 μg·kg^(-1) to 62.68 μg·kg^(-1). The addition of NH_4NO_3 in the following bioremediation led to larger reduction(34.35%) of the pesticide concentration than that of biochar(31.90%) for the contaminated soils with thermal desorption treatment, while the simultaneous addition of biochar and NH_4NO_3 led to the largest reduction of pesticide concentration(11.07%) for the soil without thermal desorption treatment. The addition of biochar and NH_4NO_3 only slightly increased the emission rate of GHGs from the soil without thermal treatment,but remarkably increased the emission rate of GHGs from the soil after thermal treatment. In most cases, the addition of NH_4NO_3 is more effective than biochar to promote the degradation of pesticide, but also exhibited higher GHG emission. The microbial community analysis suggests that the enhanced degradation of pesticide is mainly owing to the increased activity of microorganism.展开更多
The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports ...The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide(CTAB)with ammonium nitrate(NH_(4)NO_(3))salt.Surface and thermodynamic properties of cationic surfactant CTAB with NH_(4)NO_(3)were investigated at different temperatures using different techniques such as conductometry and surface tensiometery.The surface tension measurement was carried out to find out the critical micelle concentration,free energy of adsorption,free energy of micellization,minimum area per molecule,and surface excess concentration.The study reveals that the process of micellization is spontaneous and exothermic in nature.Conductance measurement was carried out to determine critical micelle concentration,degree of ionization and degree of counter ion binding.Addition of NH_(4)NO_(3)to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding,although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous.The study is very helpful to develop better understanding about interaction between electrolyte and surfactant,which are used in many applications and in different processes(e.g.,pharmaceutical,industrial foaming,drug solubilization,oil recovery,and medium for metal nanoparticle formation).展开更多
Compared with sole nitrate (NO_(3)^(-)) or sole ammonium (NH_(4)^(+)) supply,mixed nitrogen (N) supply may promote growth of maize seedlings.Previous study suggested that mixed N supply not only increased photosynthes...Compared with sole nitrate (NO_(3)^(-)) or sole ammonium (NH_(4)^(+)) supply,mixed nitrogen (N) supply may promote growth of maize seedlings.Previous study suggested that mixed N supply not only increased photosynthesis rate,but also enhanced leaf growth by increasing auxin synthesis to build a large sink for C and N utilization.However,whether this process depends on N absorption is unknown.Here,maize seedlings were grown hydroponically with three N forms (NO_(3)^(-)only,75/25 NO_(3)^(-)/NH_(4)^(+) and NH_(4)^(+) only).The study results suggested that maize growth rate and N content of shoots under mixed N supply was little different to that under sole NO_(3)^(-)supply at 0–3 d,but was higher than under sole NO_(3)^(-)supply at 6–9 d.^(15)N influx rate under mixed N supply was greater than under sole NO_(3)^(-) or NH_(4)^(+) supply at 6–9 d,although NO_(3)^(-) and NH_(4)^(+) influx under mixed N supply were reduced compared to sole NO_(3)^(-) and NH_(4)^(+) supply,respectively.qRT-PCR determination suggested that the increased N absorption under mixed N supply may be related to the higher expression of NO_(3)^(-) transporters in roots,such as ZmNRT1.1A,ZmNRT1.1B,ZmNRT1.1C,ZmNRT1.2 and ZmNRT1.3,or NH_(4)^(+) absorption transporters,such as Zm AMT1.1A,especially the latter.Furthermore,plants had higher nitrate reductase (NR)glutamine synthase (GS) activity and amino acid content under mixed N supply than when under sole NO_(3)^(-) supply.The experiments with inhibitors of NR reductase and GS synthase further confirmed that N assimilation ability under mixed N supply was necessary to promote maize growth,especially for the reduction of NO_(3)^(-) by NR reductase.This research suggested that the increased processes of NO_(3)^(-)and NH_(4)^(+) assimilation by improving N-absorption ability of roots under mixed N supply may be the main driving force to increase maize growth.展开更多
In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation m...In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NO_(x) removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO_(2)/H_(2)O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH_(3)-te mperature programmed deso rption(NH_(3)-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn^(4+) and chemisorbed oxygen species originating from enhanced interaction between MnO_x and CeO_(2),as well as improved adsorption capacity to NH_(3) and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH_(3)-SCR performance over MnCeAI-DP is related to the formation of abundant nitrate species,which is beneficial to the "NH_(4)NO_(3)" reaction pathway and thus enhances low-temperature activity.展开更多
A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are sti...A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are still unclear.Here,maize seedlings were grown hydroponically with three N supplied in three different forms (NO_(3)^(–)only,75/25 NO_(3)^(–)/NH_(4)^(+)and NH_(4)^(+)only).Compared with sole NO_(3)^(–)or NH_(4)^(+),the mixed N supply increased the total root length of maize but did not affect the number of axial roots.The main reason was the increased total lateral root length,while the average lateral root (LR) length in each axle was only slightly increased.In addition,the average LR density of 2nd whorl crown root under mixed N was also increased.Compared with sole nitrate,mixed N could improve the N metabolism of roots (such as the N influx rate,nitrate reductase (NR) and glutamine synthase (GS)enzyme activities and total amino content of the roots).Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation,and whether the NR mediated NO synthesis participates in this process needs further exploration.Meanwhile,an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation,and the changes in the sugar concentration in roots further proved this conclusion.Furthermore,the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation,in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway.This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize,which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.展开更多
An autotrophic denitrifying bioreactor with iron sulfide(FeS)as the electron donor was operated to remove ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))synergistically from wastewater for more than 298 d.The concentratio...An autotrophic denitrifying bioreactor with iron sulfide(FeS)as the electron donor was operated to remove ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))synergistically from wastewater for more than 298 d.The concentration of FeS greatly affected the removal of NH_(4)^(+)/NO_(3)^(-).Additionally,a low hydraulic retention time worsened the removal efficiency of NH_(4)^(+)/NO_(3)^(-).When the hydraulic retention time was 12 h,the optimal removal was achieved with NH_(4)^(+)and NO_(3)^(-)removal percentages both above 88%,and the corresponding nitrogen removal loading rates of NH_(4)^(+)and NO_(3)^(-)were 49.1 and 44.0 mg/(L·d),respectively.The removal of NH_(4)^(+)mainly occurred in the bottom section of the bioreactor through sulfate/ferric reducing anaerobic ammonium oxidation(Sulfammox/Feammox),nitrification,and anaerobic ammonium oxidation(Anammox)by functional microbes such as Nitrospira,Nitrosomonas,and Candidatus Kuenenia.Meanwhile,NO_(3)^(-)was mainly removed in the middle and upper sections of the bioreactor through autotrophic denitrification by Ferritrophicum,Thiobacillus,Rhodanobacter,and Pseudomonas,which possessed complete denitrification-related genes with high relative abundances.展开更多
基金Supported by the National Natural Science Foundation of China(41473070,31270544)Engineering Research Center Program of Tianjin(17PTGCCX00240)the National Water Pollution Control and Treatment Science and Technology Major Project(2015ZX07203–011-06)
文摘Organophosphorus pesticides(OPPs) are a set of toxic persistent organic pollutants(POPs) present in the environment. Recently, biochar-mediated bioremediation has exhibited many advantages over conventional methods for the remediation of pesticide-contaminated soil. In the present study, biochar and nitrogen fertilizer(NH_4NO_3)were employed to remediate OPP-contaminated soil and the greenhouse gas(GHG) emission during 90 days of incubation was investigated. After thermal desorption treatment, the content of organophosphorus pesticides reduced from 175.61 μg·kg^(-1) to 62.68 μg·kg^(-1). The addition of NH_4NO_3 in the following bioremediation led to larger reduction(34.35%) of the pesticide concentration than that of biochar(31.90%) for the contaminated soils with thermal desorption treatment, while the simultaneous addition of biochar and NH_4NO_3 led to the largest reduction of pesticide concentration(11.07%) for the soil without thermal desorption treatment. The addition of biochar and NH_4NO_3 only slightly increased the emission rate of GHGs from the soil without thermal treatment,but remarkably increased the emission rate of GHGs from the soil after thermal treatment. In most cases, the addition of NH_4NO_3 is more effective than biochar to promote the degradation of pesticide, but also exhibited higher GHG emission. The microbial community analysis suggests that the enhanced degradation of pesticide is mainly owing to the increased activity of microorganism.
文摘The study of interactions between surfactant and salt in aqueous solutions has attracted significant interest in recent years because of their widespread applications and relatively complex behavior.This work reports the systematic study of surface phenomenon and self-aggregation behavior of cationic surfactant cetyltrimethyl ammonium bromide(CTAB)with ammonium nitrate(NH_(4)NO_(3))salt.Surface and thermodynamic properties of cationic surfactant CTAB with NH_(4)NO_(3)were investigated at different temperatures using different techniques such as conductometry and surface tensiometery.The surface tension measurement was carried out to find out the critical micelle concentration,free energy of adsorption,free energy of micellization,minimum area per molecule,and surface excess concentration.The study reveals that the process of micellization is spontaneous and exothermic in nature.Conductance measurement was carried out to determine critical micelle concentration,degree of ionization and degree of counter ion binding.Addition of NH_(4)NO_(3)to the surfactant solutions increase the values of degree of ionization and degree of counter ion binding,although it lowers the values of critical micelle concentration showing that the process of micellization is more favorable and spontaneous.The study is very helpful to develop better understanding about interaction between electrolyte and surfactant,which are used in many applications and in different processes(e.g.,pharmaceutical,industrial foaming,drug solubilization,oil recovery,and medium for metal nanoparticle formation).
基金supported by the National Basic Research Program of China (2015CB150402)the National Natural Science Foundation of China (31672221 and 31421092)the Science Foundation for Young Scholars of Tobacco Research Institute of Chinese Academy of Agricultural Sciences (2022C03 and 20211302)。
文摘Compared with sole nitrate (NO_(3)^(-)) or sole ammonium (NH_(4)^(+)) supply,mixed nitrogen (N) supply may promote growth of maize seedlings.Previous study suggested that mixed N supply not only increased photosynthesis rate,but also enhanced leaf growth by increasing auxin synthesis to build a large sink for C and N utilization.However,whether this process depends on N absorption is unknown.Here,maize seedlings were grown hydroponically with three N forms (NO_(3)^(-)only,75/25 NO_(3)^(-)/NH_(4)^(+) and NH_(4)^(+) only).The study results suggested that maize growth rate and N content of shoots under mixed N supply was little different to that under sole NO_(3)^(-)supply at 0–3 d,but was higher than under sole NO_(3)^(-)supply at 6–9 d.^(15)N influx rate under mixed N supply was greater than under sole NO_(3)^(-) or NH_(4)^(+) supply at 6–9 d,although NO_(3)^(-) and NH_(4)^(+) influx under mixed N supply were reduced compared to sole NO_(3)^(-) and NH_(4)^(+) supply,respectively.qRT-PCR determination suggested that the increased N absorption under mixed N supply may be related to the higher expression of NO_(3)^(-) transporters in roots,such as ZmNRT1.1A,ZmNRT1.1B,ZmNRT1.1C,ZmNRT1.2 and ZmNRT1.3,or NH_(4)^(+) absorption transporters,such as Zm AMT1.1A,especially the latter.Furthermore,plants had higher nitrate reductase (NR)glutamine synthase (GS) activity and amino acid content under mixed N supply than when under sole NO_(3)^(-) supply.The experiments with inhibitors of NR reductase and GS synthase further confirmed that N assimilation ability under mixed N supply was necessary to promote maize growth,especially for the reduction of NO_(3)^(-) by NR reductase.This research suggested that the increased processes of NO_(3)^(-)and NH_(4)^(+) assimilation by improving N-absorption ability of roots under mixed N supply may be the main driving force to increase maize growth.
基金Project supported by the National Natural Science Foundation of China (22272077,22276097,21976081)Major Scientific and Technological Project of Bingtuan (2018AA002)。
文摘In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NO_(x) removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO_(2)/H_(2)O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH_(3)-te mperature programmed deso rption(NH_(3)-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn^(4+) and chemisorbed oxygen species originating from enhanced interaction between MnO_x and CeO_(2),as well as improved adsorption capacity to NH_(3) and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH_(3)-SCR performance over MnCeAI-DP is related to the formation of abundant nitrate species,which is beneficial to the "NH_(4)NO_(3)" reaction pathway and thus enhances low-temperature activity.
基金supported by the National Natural Science Foundation of China(31421092)the Central Publicinterest Scientific Institution Basal Research Fund,China(1610232023023)。
文摘A mixed nitrate (NO_(3)^(–)) and ammonium (NH_(4)^(+)) supply can promote root growth in maize (Zea mays),however,the changes in root morphology and the related physiological mechanism under different N forms are still unclear.Here,maize seedlings were grown hydroponically with three N supplied in three different forms (NO_(3)^(–)only,75/25 NO_(3)^(–)/NH_(4)^(+)and NH_(4)^(+)only).Compared with sole NO_(3)^(–)or NH_(4)^(+),the mixed N supply increased the total root length of maize but did not affect the number of axial roots.The main reason was the increased total lateral root length,while the average lateral root (LR) length in each axle was only slightly increased.In addition,the average LR density of 2nd whorl crown root under mixed N was also increased.Compared with sole nitrate,mixed N could improve the N metabolism of roots (such as the N influx rate,nitrate reductase (NR) and glutamine synthase (GS)enzyme activities and total amino content of the roots).Experiments with exogenously added NR and GS inhibitors suggested that the increase in the average LR length under mixed N was related to the process of N assimilation,and whether the NR mediated NO synthesis participates in this process needs further exploration.Meanwhile,an investigation of the changes in root-shoot ratio and carbon (C) concentration showed that C transportation from shoots to roots may not be the key factor in mediating lateral root elongation,and the changes in the sugar concentration in roots further proved this conclusion.Furthermore,the synthesis and transportation of auxin in axial roots may play a key role in lateral root elongation,in which the expression of ZmPIN1B and ZmPIN9 may be involved in this pathway.This study preliminarily clarified the changes in root morphology and explored the possible physiological mechanism under a mixed N supply in maize,which may provide some theoretical basis for the cultivation of crop varieties with high N efficiency.
基金This study was supported by the Guangxi Key R&D Program(No.2021AB25056)the Shenzhen Key Scientific and Technological Project(No.JSGG20191129094410446).
文摘An autotrophic denitrifying bioreactor with iron sulfide(FeS)as the electron donor was operated to remove ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))synergistically from wastewater for more than 298 d.The concentration of FeS greatly affected the removal of NH_(4)^(+)/NO_(3)^(-).Additionally,a low hydraulic retention time worsened the removal efficiency of NH_(4)^(+)/NO_(3)^(-).When the hydraulic retention time was 12 h,the optimal removal was achieved with NH_(4)^(+)and NO_(3)^(-)removal percentages both above 88%,and the corresponding nitrogen removal loading rates of NH_(4)^(+)and NO_(3)^(-)were 49.1 and 44.0 mg/(L·d),respectively.The removal of NH_(4)^(+)mainly occurred in the bottom section of the bioreactor through sulfate/ferric reducing anaerobic ammonium oxidation(Sulfammox/Feammox),nitrification,and anaerobic ammonium oxidation(Anammox)by functional microbes such as Nitrospira,Nitrosomonas,and Candidatus Kuenenia.Meanwhile,NO_(3)^(-)was mainly removed in the middle and upper sections of the bioreactor through autotrophic denitrification by Ferritrophicum,Thiobacillus,Rhodanobacter,and Pseudomonas,which possessed complete denitrification-related genes with high relative abundances.
