In this study,efficient sulfamethoxazole(SMX) degradation was demonstrated in a novel neutral FeredFenton like/oxalate(electro-Fe^2+/PDS/Ox,Fered-FL/Ox) system adopting pre-anodized Ti@Ti02 cathode.Optimization of ope...In this study,efficient sulfamethoxazole(SMX) degradation was demonstrated in a novel neutral FeredFenton like/oxalate(electro-Fe^2+/PDS/Ox,Fered-FL/Ox) system adopting pre-anodized Ti@Ti02 cathode.Optimization of operational parameters was conducted and the whole reaction mechanism based on the critical solid-liquid interfacial reactions was explored.An efficient neutral heterogeneous-homogenous iron cyclewould exist in the Fered-FL/Ox system,depending on the formation of specific C-O-Ti bonds through the inner sphere surface complex(ISSC) of Fe(C2 O4)3^3-.It would induce ultrafast electron transfer from the cathode to the FeⅢ core,effectively accelerating the neutral Fenton-like reactions and complete mineralization of SMX with relative low dosage of ferrous catalyst and applied voltage.The result of this study is expected to supply a good alternative in treating complex neutral industrial wastewaters.展开更多
Heterogeneous Fenton has been widely used in the disposal of organic pollutants,however,slow regeneration of≡Fe(II)remains limitation for its practical application of long-term treatment.Herein,we come up with a nove...Heterogeneous Fenton has been widely used in the disposal of organic pollutants,however,slow regeneration of≡Fe(II)remains limitation for its practical application of long-term treatment.Herein,we come up with a novel Fe-based heterogeneous Fenton catalyst named as FeS_(x)O_(y)-X(X is the ratio of ethylene glycol to N,N-dimethylformamide).With the help of the abundant defect electrons in Sulfur vacancies,≡Fe(Ⅱ)regeneration on the surface of FeS_(x)O_(y)-1:1 was accelerated,resulting in a stable proportion of≡Fe(Ⅱ)on the surface,which maintained continuously stable generation of hydroxyl radical(·OH)and singlet oxygen(^(1)O_(2)).Thus,without any organic reagents or cocatalysts,FeS_(x)O_(y)-1:1 based Fenton system achieved effective long-term degradation of 560 mg/L quinoline within only 7 days,which was evidently better than reported Fe S and SV-Fe S_(2)(SV:Sulfur vacancy).The system had excellent adaptability to water quality and the COD removal rate of biochemical wastewater was as high as 79.8%.展开更多
Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the ocea...Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the oceans.In this study,we screened 1546 strains from marine seawater and sediments,which were deposited in the Marine Culture Collection of China(MCCC),and further analyzed the diversity of positive strains and their potential genes related to iron acquisition.Of the 1546 isolates,856 strains(55.37%)showed positive siderophore-producing activity on the Chrome Azurol Sulfonate(CAS)plates.Among these,isolates from seawater environments had a higher positive proportion(535).Some genera showed a higher proportion(>70%)of positive siderophore producers,such as Alteromonas(89/112),Marinobacter(78/109),Vibrio(21/27),Shewanella(7/8)in the Gammaproteobacteria,Sulfitobacter(17/21),Martelella(5/6)in the Alphaproteobacteria,and Joostella(6/7)in the phylum Bacteroidetes.Siderophore biosynthesis genes,including those for vanchrobactin,vibrioferrin,petrobactin,and aerobactin,as well as transport and iron storage proteins,were also identified in the positive bacterial genomes.The study revealed that a variety of bacterial strains demonstrate the production of siderophores,which could significantly contribute to the iron cycle within marine ecosystems,encompassing both seawater and marine sediments.展开更多
The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric du...The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric dust deposition are the primary processes introducing Fe into the ocean.Also,subsequent physical processes are crucial in transporting biologically available Fe into the upper ocean.As anthropogenic dust increases,the Fe from anthropogenic activities is expected to become more important in terms of impacting marine ecosystems.To investigate the Fe cycle and its impact on ecosystems,a project entitled‘The sources and transport of Fe in the North Pacific and its impact on marine ecosystems’has been funded by the National Natural Science Foundation of China.The project will focus on three major scientific questions:(1)What are the major sources of Fe in the North Pacific?(2)What is the influence of the Fe-binding ligand cycle on marine ecosystems?(3)What is the likely influence of global change in the future?The distribution of Fe and its corresponding impact on the marine ecosystem in current and future environmental conditions will be investigated.The results of the project are expected to improve our understanding of the marine ecosystem in the North Pacific.展开更多
Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the cell.These structures are ferrimagnetic organelles that impart a magnetic ...Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the cell.These structures are ferrimagnetic organelles that impart a magnetic moment to the cell.To succeed in producing magnetosomes,MTB accumulate iron in(i)cytoplasm;(ⅱ)magnetosomes;and(ⅲ)nearby the organelle.It has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia coli.Phages are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and pump.The current work addresses the putative role of phages that infect MTB on the iron biogeochemical cycle.Can phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments?Are phages critical players in driving magnetosome biomineralization genes(BGs)horizontal transfer?Further investigation of those events,including frequency of occurrence,is necessary to fully comprehend MTB’s effect on iron cycling in aqueous environments.展开更多
The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affect...The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affects the dissolution of vanadium through the catalytic effect on Fe^3+/Fe^2+couple and material exchange.The passivation of iron settling correlates with ferrous ion content in bio-leaching solution.In medium containing A.ferrooxidans and Fe(Ⅲ),the increment in Fe(Ⅱ)concentration leads to the formation of jarosite,generating a decline in vanadium extraction efficiency.Analysis of cyclic voltammetry shows that Fe(Ⅱ)ion is apt to be oxidized and translated into precipitate by A.ferrooxidans,which strongly adsorbed to the surface of the residue.Fe(Ⅲ)ion promotes the vanadium extraction due to its oxidizing activity.Admixing A.ferrooxidans to Fe(Ⅲ)medium elevates the reduction of low valence state vanadium and facilitates the exchange of substance between minerals and solution.This motivates 3.8%and 21.8%increments in recovery ratio and leaching rate of vanadium compared to the Fe(Ⅲ)exclusive use,respectively.Moreover,Fe(Ⅱ)ion impacts vanadium extraction slightly in sterile medium but negatively influences vanadium leaching in the presence of bacteria.展开更多
●Fe-OC content decreased after the mattic layer slipped at the same soil horizon.●Fe-OC and Fe redox gene diversity increased after the mattic layer slipped.●The content of Fe-OC was influenced by RES-Fe and RED-Fe...●Fe-OC content decreased after the mattic layer slipped at the same soil horizon.●Fe-OC and Fe redox gene diversity increased after the mattic layer slipped.●The content of Fe-OC was influenced by RES-Fe and RED-Fe.●RES-Fe and RED-Fe are mainly driven by genes fhuE and narI,respectively.Iron(Fe)binding was an important mechanism for the stabilisation of organic carbon(C)in soils.Slipping of the mattic layer exposes soils and changes the microbial Fe cycling and iron-bound organic carbon(Fe-OC)distribution.The coupled relationships were investigated among Fe,C,and key Fe redox cycling functional genes in the alpine meadows with and without mattic layer in the Qinghai-Tibet Plateau.Compared with the meadow layer and eluvial horizon,SOC content decreased by 17.7 g kg^(-1)from 39.7−90.3 g kg^(-1)after the mattic layer slipped,while the Fe-OC%increased from 2.7%and 5.7%to 12.7%.The proportion of the residual Fe fraction(RES-Fe)increased by 5.2%to 7.9%,and the organic matter-bound Fe fraction(OM-Fe)was decreased by 6%,the shift in Fe fractions caused an increase of Fe-OC%.Furthermore,the total average signal intensity of the genes for Fe cycling and redox was increased.The proportion of RES-Fe increased with CirA,feoB,fhuE and ahpC,fnr,narJ,perR,and soxR.The proportion of RED-Fe decreased with the fhuE and narI genes.In conclusion,the shift in Fe redox genes can be expected to increase the RES-Fe fractions,which promoted the accumulation of Fe-OC after the mattic layer slipped.展开更多
In this study,a carbon quantum dots modified maghemite catalyst(CQDs@γ-Fe_(2)O_(3))has been synthesized by a one-step solvothermal method for efficient persulfate(PDS)activation under visible light irradiation.Transm...In this study,a carbon quantum dots modified maghemite catalyst(CQDs@γ-Fe_(2)O_(3))has been synthesized by a one-step solvothermal method for efficient persulfate(PDS)activation under visible light irradiation.Transmission electron microscopy(TEM),scanning electron microscopy(SEM)and UV-vis diffuse reflectance spectroscopy(UV-vis DRS)characterization indicated that the formation of heterojunction structure between CQDs and y-Fe_(2)O_(3) effectively reduced the catalyst band gap(Eg),favoring the separation rate of electrons and holes,leading to remarkable efficient sulfamethoxazole(SMX)degradation as compared to the dark-CQDs@γ-Fe_(2)O_(3)/PDS and vis-γ-Fe_(2)O_(3)/PDS systems.The evolution of dissolved irons also demonstrated that CQDs could accelerate the in-situ reduction of surface-bounded Fe^(3+).Electron paramagnetic resonance(EPR)and radical scavenging experiments demonstrated that both*OH and SO_(4)·were generated in the reaction system,while*OH was relatively more dominant than SO_(4)·for SMX degradation.Finally,the reaction mechanism in the vis-CQDs@y-Fe_(2)O_(3)/PDS system was proposed involving an effective and accelerated heterogeneous-homogeneous iron cycle.CQDs would enrich the photo-generated electrons from y-Fe_(2)O_(3),causing efficient interfacial generation of surfacebond Fe^(2+)and reduction of adsorbed Fe3+.This visible light induced iron cycle would eventually lead to effective activation of PDS as well as the efficient degradation of SMX.展开更多
Nanometer-size zero-valent iron(NZVI)is an efficient reducing agent,but its surface is easily passivated with an oxide layer,leading to reaction inefficiency.In our study,oxalate(OA)was introduced into this heterogene...Nanometer-size zero-valent iron(NZVI)is an efficient reducing agent,but its surface is easily passivated with an oxide layer,leading to reaction inefficiency.In our study,oxalate(OA)was introduced into this heterogeneous system of NZVI,which could form ferrioxalate complexes with the NZVI surface-bound Fe3+and dissolved Fe3+in the solution.Photolysis of ferrioxalate complexes can facilitate the generation of Fe2+from Fe3+and CO_(2)·-radical,both species have strong reduction capacity.Hence,a"photo-oxalate-Fe(0)"system through sunlight induction was established,which not only prohibited the formation of a surface passivation layer,but also displayed a synergetic mechanism of ferrioxalate photolysis to enhance reduction,exhibiting remarkably higher degradation activity(several times faster)toward the model pollutant Cr(Ⅵ)than the mechanism with NZVI alone.Factor tests suggested that both NZVI dosage and OA content markedly affected the reduction rate.Low pH was beneficial to the reduction efficiency.Moreover,recyclability experiment showed that the reduction rate decreased from 0.21706 to 0.03977 min-1 after three cycles of reuse due to the NZVI losing reaction activity generally,but the system still maintained considerable reduction capacity.Finally,a mechanism was revealed whereby NZVI would transform to Fe oxides after the exhaustion of its reductive power,and the photolysis of ferrioxalate to promote the cycling of iron species played the predominant role in providing extra reduction ability.These features confirm that introduction of OA into Cr(Ⅵ)reduction by NZVI through sunlight induction is advantageous and promising.展开更多
Electron shuttles such cysteine play an important role in Fe cycle and its availability in soils,while the roles of pH and organic ligands in this process are poorly understood.Herein,the reductive dissolution process...Electron shuttles such cysteine play an important role in Fe cycle and its availability in soils,while the roles of pH and organic ligands in this process are poorly understood.Herein,the reductive dissolution process of goethite by cysteine were explored in the presence of organic ligands.Our results showed that cysteine exhibited a strong reactivity towards goethite-a typical iron minerals in paddy soils with a rate constant ranging from 0.01 to0.1 hr^(-1).However,a large portion of Fe(Ⅱ)appeared to be"structural species"retained on the surface.The decline of pH was favorable to generate more Fe(Ⅱ)ions and enhancing tendency of Fe(Ⅱ)release to solution.The decline of generation of Fe(Ⅱ)by increasing pH was likely to be caused by a lower redox potential and the nature of cysteine pH-dependent adsorption towards goethite.Interestingly,the co-existence of oxalate and citrate ligands also enhanced the rate constant of Fe(Ⅱ)release from 0.09 to 0.15 hr-1;nevertheless,they negligibly affected the overall generation of Fe(Ⅱ)in opposition to the pH effect.Further spectroscopic evidence demonstrated that two molecules of cysteine could form disulfide bonds(S-S)to generate cystine through oxidative dehydration,and subsequently,inducing electron transfer from cysteine to the structural Fe(Ⅲ)on goethite;meanwhile,those organic ligands act as Fe(Ⅱ)"strippers".The findings of this work provide new insights into the understanding of the different roles of pH and organic ligands on the generation and release of Fe induced by electron shuttles in soils.展开更多
Redox cycling of iron plays a pivotal role in both nutrient acquisition by living organisms and the geochemical cycling of elements in aquatic environments.In nature,iron cycling is mediated by microbial Fe(II)-oxidiz...Redox cycling of iron plays a pivotal role in both nutrient acquisition by living organisms and the geochemical cycling of elements in aquatic environments.In nature,iron cycling is mediated by microbial Fe(II)-oxidizers and Fe(III)-reducers or through the interplay of biotic and abiotic iron transformation processes.Here,we unveil a specific iron cycling process driven by one single phototrophic species,Rhodobacter ferrooxidans SW2.It exhibits the capability to reduce Fe(III)during bacterial cultivation.A c-type cytochrome is identified with Fe(III)-reducing activity,implying the linkage of Fe(III)reduction with the electron transport system.R.ferrooxidans SW2 can mediate iron redox transformation,depending on the availability of light and/or organic substrates.Iron cycling driven by anoxygenic photoferrotrophs is proposed to exist worldwide in modern and ancient environments.Our work not only enriches the theoretical basis of iron cycling in nature but also implies multiple roles of anoxygenic photoferrotrophs in iron transformation processes.展开更多
Constructed wetlands(CWs)are widely applied for decentralized wastewater treatment.However,achieving efficient removal of ammonia(NH+-N)has proven challenging due to insufficient oxygen.In this study,natural hematite(...Constructed wetlands(CWs)are widely applied for decentralized wastewater treatment.However,achieving efficient removal of ammonia(NH+-N)has proven challenging due to insufficient oxygen.In this study,natural hematite(Fe,O3)was employed as a CW substrate(H-CWs)for the first time to drive anaerobic ammonia oxidation coupled with iron(I)reduction(Feammox).Compared to gravel constructed wetlands(G-CWs),ammonia removal was enhanced by 38.14%to 54.03%and nitrous oxide(N_(2)0)emissions were reduced by 34.60%in H-CWs.The synergistic removal of ammonia and nitrate by H-CWs also resulted in the absence of ammoxidation by-products.Inhibitor and 15N isotope tracer incubations showed that Feammox accounting for approximately 40%of all ammonia removal in the H-CWs.The enrichment of iron phosphate(Fe_(3)Fe_(4)(PO_(4))_(6))promoted the accumulation of the Feammox intermediate compound FeOOH.Microbial nanowires were observed on the surface of H-CW substrates as well,suggesting that the observed biological ammoxidation was most likely related to extracellular electron transfer(EET).Microbial and metagenomics analysis revealed that H-CWs elevated the integrity and enhanced the abundance of functional microorganisms and genes associated with nitrogen metabolism.Overall,the efficient ammonia removal in the absence of O2 together with a reduction in N_(2)O emissions as described in this study may provide useful guidance for hematite-mediated anaerobic ammonia removal in CWs.展开更多
The saline and buffered environment in actual wastewater imposes higher demands on Fenton and Fenton-like catalytic systems.This study developed a MoS_(2)co-catalytic Fe_(2)O_(3)Fenton-like system with controllable Le...The saline and buffered environment in actual wastewater imposes higher demands on Fenton and Fenton-like catalytic systems.This study developed a MoS_(2)co-catalytic Fe_(2)O_(3)Fenton-like system with controllable Lewis acid-base sites,achieving efficient treatment of various model pollutants and actual industrial wastewater under neutral buffered environment.The acidic microenvironment structured by the edge S sites(Lewis basic sites)in the MoS_(2)/Fe_(2)O_(3)catalyst is susceptible to the influence of Lewis acidic sites constructed by Mo and Fe element,affecting catalytic performance.Optimizing the ratio of precursor amounts ensures the stable presence of the acidic microenvironment on the surface of catalyst,enabling the beneficial co-catalytic effect of Mo sites to be realized.Furthermore,it transcends the rigid constraints imposed by the Fenton reaction on reaction environments,thereby expanding the applicability of commonplace oxides such as Fe_(2)O_(3)in actual industrial water remediation.展开更多
The dissimilatory reduction of Fe(III)oxides driven by Fe(III)-reducing bacteria(FRB)is an important biogeo-chemical process that influences not only iron cycling but also the biogeochemical cycles of carbon,trace met...The dissimilatory reduction of Fe(III)oxides driven by Fe(III)-reducing bacteria(FRB)is an important biogeo-chemical process that influences not only iron cycling but also the biogeochemical cycles of carbon,trace metals,nutrients and contaminants.Phages have central roles in modulating the population and activity of FRB,but the mechanism for phage-involved Fe(III)oxide reduction is still unclear.This work used a common FRB,Geobacter soli,to explore the roles and underlying mechanisms of FRB-harboring prophages in the dissimilatory reduction of Fe(III)oxides.Bioinformatic analysis predicted 185 phage-related genes in the G.soli genome,comprising functional prophages that were verified to be induced to form tailed phage particles.Ferrihydrite reduction was facilitated as prophage induction was stimulated and declined as prophage induction was inhibited,which indi-cated a positive role of G.soli-harboring prophages in Fe(III)oxide reduction.A comparison of gene expression and released phage particles in the cells grown with Fe(III)-citrate and ferrihydrite suggested that microbial fer-rihydrite reduction would activate the SOS response and consequently induce the prophages to enter lytic cycles.The prophage-mediated lysis of the subpopulation resulted in an increased release of extracellular DNA and mem-brane vesicles that were conducive to Fe(III)oxide reduction,which might explain the positive role of prophages in ferrihydrite reduction.In summary,our results revealed the functional roles and underlying mechanisms of FRB-associated prophages in facilitating the dissimilatory reduction of Fe(III)oxides,which will advance our understanding of iron cycling in natural ecosystems.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.21677055 and 21407052)the Fundamental Research Funds for the Central Universities,HUST (Nos.2017KFXKJC004 and 2016YXMS287)
文摘In this study,efficient sulfamethoxazole(SMX) degradation was demonstrated in a novel neutral FeredFenton like/oxalate(electro-Fe^2+/PDS/Ox,Fered-FL/Ox) system adopting pre-anodized Ti@Ti02 cathode.Optimization of operational parameters was conducted and the whole reaction mechanism based on the critical solid-liquid interfacial reactions was explored.An efficient neutral heterogeneous-homogenous iron cyclewould exist in the Fered-FL/Ox system,depending on the formation of specific C-O-Ti bonds through the inner sphere surface complex(ISSC) of Fe(C2 O4)3^3-.It would induce ultrafast electron transfer from the cathode to the FeⅢ core,effectively accelerating the neutral Fenton-like reactions and complete mineralization of SMX with relative low dosage of ferrous catalyst and applied voltage.The result of this study is expected to supply a good alternative in treating complex neutral industrial wastewaters.
基金supported by the National Natural Science Foundation of China(No.22176060)Project supported by Shanghai Municipal Science and Technology Major Project(No.2018SHZDZX03)+1 种基金the Program of Introducing Talents of Discipline to Universities(No.B16017)the Science and Technology Commission of Shanghai Municipality(No.20DZ2250400)。
文摘Heterogeneous Fenton has been widely used in the disposal of organic pollutants,however,slow regeneration of≡Fe(II)remains limitation for its practical application of long-term treatment.Herein,we come up with a novel Fe-based heterogeneous Fenton catalyst named as FeS_(x)O_(y)-X(X is the ratio of ethylene glycol to N,N-dimethylformamide).With the help of the abundant defect electrons in Sulfur vacancies,≡Fe(Ⅱ)regeneration on the surface of FeS_(x)O_(y)-1:1 was accelerated,resulting in a stable proportion of≡Fe(Ⅱ)on the surface,which maintained continuously stable generation of hydroxyl radical(·OH)and singlet oxygen(^(1)O_(2)).Thus,without any organic reagents or cocatalysts,FeS_(x)O_(y)-1:1 based Fenton system achieved effective long-term degradation of 560 mg/L quinoline within only 7 days,which was evidently better than reported Fe S and SV-Fe S_(2)(SV:Sulfur vacancy).The system had excellent adaptability to water quality and the COD removal rate of biochemical wastewater was as high as 79.8%.
基金The National Key Research and Development Program of China under contact No.2021YFF0501304the Natural Science Foundation of Xiamen,China under contact No.3502Z20227244the Scientific Research Foundation of the Third Institute of Oceanography,MNR under contact Nos 2019021 and 2022009.
文摘Low iron content is a peculiar feature of marine ecosystems,where microbes have to produce iron-chelating molecules such as siderophores to survive.Very little is known about siderophore-producing bacteria in the oceans.In this study,we screened 1546 strains from marine seawater and sediments,which were deposited in the Marine Culture Collection of China(MCCC),and further analyzed the diversity of positive strains and their potential genes related to iron acquisition.Of the 1546 isolates,856 strains(55.37%)showed positive siderophore-producing activity on the Chrome Azurol Sulfonate(CAS)plates.Among these,isolates from seawater environments had a higher positive proportion(535).Some genera showed a higher proportion(>70%)of positive siderophore producers,such as Alteromonas(89/112),Marinobacter(78/109),Vibrio(21/27),Shewanella(7/8)in the Gammaproteobacteria,Sulfitobacter(17/21),Martelella(5/6)in the Alphaproteobacteria,and Joostella(6/7)in the phylum Bacteroidetes.Siderophore biosynthesis genes,including those for vanchrobactin,vibrioferrin,petrobactin,and aerobactin,as well as transport and iron storage proteins,were also identified in the positive bacterial genomes.The study revealed that a variety of bacterial strains demonstrate the production of siderophores,which could significantly contribute to the iron cycle within marine ecosystems,encompassing both seawater and marine sediments.
基金supported by the National Natural Science Foundation of China(NSFC)[grant number 41730536]
文摘The limitation of iron(Fe)makes the North Pacific a typically high-nitrate,low-chlorophyll(HNLC)region in comparison with other oceanic regions of the world.Iron inputs from land via river discharge and atmospheric dust deposition are the primary processes introducing Fe into the ocean.Also,subsequent physical processes are crucial in transporting biologically available Fe into the upper ocean.As anthropogenic dust increases,the Fe from anthropogenic activities is expected to become more important in terms of impacting marine ecosystems.To investigate the Fe cycle and its impact on ecosystems,a project entitled‘The sources and transport of Fe in the North Pacific and its impact on marine ecosystems’has been funded by the National Natural Science Foundation of China.The project will focus on three major scientific questions:(1)What are the major sources of Fe in the North Pacific?(2)What is the influence of the Fe-binding ligand cycle on marine ecosystems?(3)What is the likely influence of global change in the future?The distribution of Fe and its corresponding impact on the marine ecosystem in current and future environmental conditions will be investigated.The results of the project are expected to improve our understanding of the marine ecosystem in the North Pacific.
文摘Magnetotactic bacteria(MTB)are ubiquitous prokaryotes that orient along magnetic field lines due to magnetosomes’biomineralization within the cell.These structures are ferrimagnetic organelles that impart a magnetic moment to the cell.To succeed in producing magnetosomes,MTB accumulate iron in(i)cytoplasm;(ⅱ)magnetosomes;and(ⅲ)nearby the organelle.It has already been estimated that a single MTB has an iron content of 10 to 100-fold higher than Escherichia coli.Phages are the most abundant entity in oceans and are known for controlling nutrient flow such as carbon and nitrogen by viral shunt and pump.The current work addresses the putative role of phages that infect MTB on the iron biogeochemical cycle.Can phage infection in MTB hosts cause a biogenic iron fertilization-like event in localized microenvironments?Are phages critical players in driving magnetosome biomineralization genes(BGs)horizontal transfer?Further investigation of those events,including frequency of occurrence,is necessary to fully comprehend MTB’s effect on iron cycling in aqueous environments.
基金Project(DY135-B2-15) supported by the China Ocean Mineral Resource R&D AssociationProject(2015ZX07205-003) supported by Major Science and Technology Program for Water Pollution Control and Treatment,ChinaProjects(21176242,21176026) supported by the National Natural Science Foundation of China
文摘The acid bio-leaching process of vanadium extraction from clay vanadium water-leached residue was studied and the effect of the performance of iron transformation was investigated.Acidithiobacillus ferrooxidans affects the dissolution of vanadium through the catalytic effect on Fe^3+/Fe^2+couple and material exchange.The passivation of iron settling correlates with ferrous ion content in bio-leaching solution.In medium containing A.ferrooxidans and Fe(Ⅲ),the increment in Fe(Ⅱ)concentration leads to the formation of jarosite,generating a decline in vanadium extraction efficiency.Analysis of cyclic voltammetry shows that Fe(Ⅱ)ion is apt to be oxidized and translated into precipitate by A.ferrooxidans,which strongly adsorbed to the surface of the residue.Fe(Ⅲ)ion promotes the vanadium extraction due to its oxidizing activity.Admixing A.ferrooxidans to Fe(Ⅲ)medium elevates the reduction of low valence state vanadium and facilitates the exchange of substance between minerals and solution.This motivates 3.8%and 21.8%increments in recovery ratio and leaching rate of vanadium compared to the Fe(Ⅲ)exclusive use,respectively.Moreover,Fe(Ⅱ)ion impacts vanadium extraction slightly in sterile medium but negatively influences vanadium leaching in the presence of bacteria.
基金supported by the West Light Foundation of the Chinese Academy of Sciences(Grant No.xbzg-zdsys-202009)the Second Tibetan Plateau Scientific Expedition and Research Program(Grant No.2019QZKK0603)the Strategic Priority Research Program of the Chinese Academy of Sciences(PanThird Pole Environment Study for a Green Silk Road,No:XDA20040202).
文摘●Fe-OC content decreased after the mattic layer slipped at the same soil horizon.●Fe-OC and Fe redox gene diversity increased after the mattic layer slipped.●The content of Fe-OC was influenced by RES-Fe and RED-Fe.●RES-Fe and RED-Fe are mainly driven by genes fhuE and narI,respectively.Iron(Fe)binding was an important mechanism for the stabilisation of organic carbon(C)in soils.Slipping of the mattic layer exposes soils and changes the microbial Fe cycling and iron-bound organic carbon(Fe-OC)distribution.The coupled relationships were investigated among Fe,C,and key Fe redox cycling functional genes in the alpine meadows with and without mattic layer in the Qinghai-Tibet Plateau.Compared with the meadow layer and eluvial horizon,SOC content decreased by 17.7 g kg^(-1)from 39.7−90.3 g kg^(-1)after the mattic layer slipped,while the Fe-OC%increased from 2.7%and 5.7%to 12.7%.The proportion of the residual Fe fraction(RES-Fe)increased by 5.2%to 7.9%,and the organic matter-bound Fe fraction(OM-Fe)was decreased by 6%,the shift in Fe fractions caused an increase of Fe-OC%.Furthermore,the total average signal intensity of the genes for Fe cycling and redox was increased.The proportion of RES-Fe increased with CirA,feoB,fhuE and ahpC,fnr,narJ,perR,and soxR.The proportion of RED-Fe decreased with the fhuE and narI genes.In conclusion,the shift in Fe redox genes can be expected to increase the RES-Fe fractions,which promoted the accumulation of Fe-OC after the mattic layer slipped.
基金the National Natural Science Foundation of China(Nos.21677055,21407052)the Fundamental Research Funds for the Central Universities,Huazhong University of Science and Technology(HUST)(Nos.2017KFXKJC004,2016YXMS287)。
文摘In this study,a carbon quantum dots modified maghemite catalyst(CQDs@γ-Fe_(2)O_(3))has been synthesized by a one-step solvothermal method for efficient persulfate(PDS)activation under visible light irradiation.Transmission electron microscopy(TEM),scanning electron microscopy(SEM)and UV-vis diffuse reflectance spectroscopy(UV-vis DRS)characterization indicated that the formation of heterojunction structure between CQDs and y-Fe_(2)O_(3) effectively reduced the catalyst band gap(Eg),favoring the separation rate of electrons and holes,leading to remarkable efficient sulfamethoxazole(SMX)degradation as compared to the dark-CQDs@γ-Fe_(2)O_(3)/PDS and vis-γ-Fe_(2)O_(3)/PDS systems.The evolution of dissolved irons also demonstrated that CQDs could accelerate the in-situ reduction of surface-bounded Fe^(3+).Electron paramagnetic resonance(EPR)and radical scavenging experiments demonstrated that both*OH and SO_(4)·were generated in the reaction system,while*OH was relatively more dominant than SO_(4)·for SMX degradation.Finally,the reaction mechanism in the vis-CQDs@y-Fe_(2)O_(3)/PDS system was proposed involving an effective and accelerated heterogeneous-homogeneous iron cycle.CQDs would enrich the photo-generated electrons from y-Fe_(2)O_(3),causing efficient interfacial generation of surfacebond Fe^(2+)and reduction of adsorbed Fe3+.This visible light induced iron cycle would eventually lead to effective activation of PDS as well as the efficient degradation of SMX.
基金supported by Project funded by China Postdoctoral Science Foundation(No.2017M611533)
文摘Nanometer-size zero-valent iron(NZVI)is an efficient reducing agent,but its surface is easily passivated with an oxide layer,leading to reaction inefficiency.In our study,oxalate(OA)was introduced into this heterogeneous system of NZVI,which could form ferrioxalate complexes with the NZVI surface-bound Fe3+and dissolved Fe3+in the solution.Photolysis of ferrioxalate complexes can facilitate the generation of Fe2+from Fe3+and CO_(2)·-radical,both species have strong reduction capacity.Hence,a"photo-oxalate-Fe(0)"system through sunlight induction was established,which not only prohibited the formation of a surface passivation layer,but also displayed a synergetic mechanism of ferrioxalate photolysis to enhance reduction,exhibiting remarkably higher degradation activity(several times faster)toward the model pollutant Cr(Ⅵ)than the mechanism with NZVI alone.Factor tests suggested that both NZVI dosage and OA content markedly affected the reduction rate.Low pH was beneficial to the reduction efficiency.Moreover,recyclability experiment showed that the reduction rate decreased from 0.21706 to 0.03977 min-1 after three cycles of reuse due to the NZVI losing reaction activity generally,but the system still maintained considerable reduction capacity.Finally,a mechanism was revealed whereby NZVI would transform to Fe oxides after the exhaustion of its reductive power,and the photolysis of ferrioxalate to promote the cycling of iron species played the predominant role in providing extra reduction ability.These features confirm that introduction of OA into Cr(Ⅵ)reduction by NZVI through sunlight induction is advantageous and promising.
基金supported by the National Natural Science Foundation of China(Nos.42077301,21876161)the National Key Research and Development Project of China(No.2020YFC1808702)Guangdong Academy of Sciences’Project(No.2019GDASYL-0102006).
文摘Electron shuttles such cysteine play an important role in Fe cycle and its availability in soils,while the roles of pH and organic ligands in this process are poorly understood.Herein,the reductive dissolution process of goethite by cysteine were explored in the presence of organic ligands.Our results showed that cysteine exhibited a strong reactivity towards goethite-a typical iron minerals in paddy soils with a rate constant ranging from 0.01 to0.1 hr^(-1).However,a large portion of Fe(Ⅱ)appeared to be"structural species"retained on the surface.The decline of pH was favorable to generate more Fe(Ⅱ)ions and enhancing tendency of Fe(Ⅱ)release to solution.The decline of generation of Fe(Ⅱ)by increasing pH was likely to be caused by a lower redox potential and the nature of cysteine pH-dependent adsorption towards goethite.Interestingly,the co-existence of oxalate and citrate ligands also enhanced the rate constant of Fe(Ⅱ)release from 0.09 to 0.15 hr-1;nevertheless,they negligibly affected the overall generation of Fe(Ⅱ)in opposition to the pH effect.Further spectroscopic evidence demonstrated that two molecules of cysteine could form disulfide bonds(S-S)to generate cystine through oxidative dehydration,and subsequently,inducing electron transfer from cysteine to the structural Fe(Ⅲ)on goethite;meanwhile,those organic ligands act as Fe(Ⅱ)"strippers".The findings of this work provide new insights into the understanding of the different roles of pH and organic ligands on the generation and release of Fe induced by electron shuttles in soils.
基金supported by the National Natural Science Foundation of China(51821006,52192684,and 22176043).
文摘Redox cycling of iron plays a pivotal role in both nutrient acquisition by living organisms and the geochemical cycling of elements in aquatic environments.In nature,iron cycling is mediated by microbial Fe(II)-oxidizers and Fe(III)-reducers or through the interplay of biotic and abiotic iron transformation processes.Here,we unveil a specific iron cycling process driven by one single phototrophic species,Rhodobacter ferrooxidans SW2.It exhibits the capability to reduce Fe(III)during bacterial cultivation.A c-type cytochrome is identified with Fe(III)-reducing activity,implying the linkage of Fe(III)reduction with the electron transport system.R.ferrooxidans SW2 can mediate iron redox transformation,depending on the availability of light and/or organic substrates.Iron cycling driven by anoxygenic photoferrotrophs is proposed to exist worldwide in modern and ancient environments.Our work not only enriches the theoretical basis of iron cycling in nature but also implies multiple roles of anoxygenic photoferrotrophs in iron transformation processes.
基金This work was funded by the National Natural Science Foundation of China(No.52170150)Chongqing Science Fund for Distinguished Young Scholars(China)(No.CSTB2022NSCQ-JQX0023)Fundamental Research Funds for the Central Universities(China)(No.2020CDJDPT002).
文摘Constructed wetlands(CWs)are widely applied for decentralized wastewater treatment.However,achieving efficient removal of ammonia(NH+-N)has proven challenging due to insufficient oxygen.In this study,natural hematite(Fe,O3)was employed as a CW substrate(H-CWs)for the first time to drive anaerobic ammonia oxidation coupled with iron(I)reduction(Feammox).Compared to gravel constructed wetlands(G-CWs),ammonia removal was enhanced by 38.14%to 54.03%and nitrous oxide(N_(2)0)emissions were reduced by 34.60%in H-CWs.The synergistic removal of ammonia and nitrate by H-CWs also resulted in the absence of ammoxidation by-products.Inhibitor and 15N isotope tracer incubations showed that Feammox accounting for approximately 40%of all ammonia removal in the H-CWs.The enrichment of iron phosphate(Fe_(3)Fe_(4)(PO_(4))_(6))promoted the accumulation of the Feammox intermediate compound FeOOH.Microbial nanowires were observed on the surface of H-CW substrates as well,suggesting that the observed biological ammoxidation was most likely related to extracellular electron transfer(EET).Microbial and metagenomics analysis revealed that H-CWs elevated the integrity and enhanced the abundance of functional microorganisms and genes associated with nitrogen metabolism.Overall,the efficient ammonia removal in the absence of O2 together with a reduction in N_(2)O emissions as described in this study may provide useful guidance for hematite-mediated anaerobic ammonia removal in CWs.
基金supported by the National Natural Science Foundation of China(Nos.22176060 and 41876189)the Program of Shanghai Academic/Technology Research Leader(23XD1421000)+3 种基金Shanghai Municipal Science and Technology Major Project(Grant No.2018SHZDZX03)the Program of Introducing Talents of Discipline to Universities(B16017)Science and Technology Commission of Shanghai Municipality(20DZ2250400)the Fundamental Research Funds for the Central Universities(222201717003)。
文摘The saline and buffered environment in actual wastewater imposes higher demands on Fenton and Fenton-like catalytic systems.This study developed a MoS_(2)co-catalytic Fe_(2)O_(3)Fenton-like system with controllable Lewis acid-base sites,achieving efficient treatment of various model pollutants and actual industrial wastewater under neutral buffered environment.The acidic microenvironment structured by the edge S sites(Lewis basic sites)in the MoS_(2)/Fe_(2)O_(3)catalyst is susceptible to the influence of Lewis acidic sites constructed by Mo and Fe element,affecting catalytic performance.Optimizing the ratio of precursor amounts ensures the stable presence of the acidic microenvironment on the surface of catalyst,enabling the beneficial co-catalytic effect of Mo sites to be realized.Furthermore,it transcends the rigid constraints imposed by the Fenton reaction on reaction environments,thereby expanding the applicability of commonplace oxides such as Fe_(2)O_(3)in actual industrial water remediation.
基金supported by the National Natural Science Foundation of China(42077211)the Natural Science Foundation of Guangdong Province(2021A1515012570,2022A1515011734).
文摘The dissimilatory reduction of Fe(III)oxides driven by Fe(III)-reducing bacteria(FRB)is an important biogeo-chemical process that influences not only iron cycling but also the biogeochemical cycles of carbon,trace metals,nutrients and contaminants.Phages have central roles in modulating the population and activity of FRB,but the mechanism for phage-involved Fe(III)oxide reduction is still unclear.This work used a common FRB,Geobacter soli,to explore the roles and underlying mechanisms of FRB-harboring prophages in the dissimilatory reduction of Fe(III)oxides.Bioinformatic analysis predicted 185 phage-related genes in the G.soli genome,comprising functional prophages that were verified to be induced to form tailed phage particles.Ferrihydrite reduction was facilitated as prophage induction was stimulated and declined as prophage induction was inhibited,which indi-cated a positive role of G.soli-harboring prophages in Fe(III)oxide reduction.A comparison of gene expression and released phage particles in the cells grown with Fe(III)-citrate and ferrihydrite suggested that microbial fer-rihydrite reduction would activate the SOS response and consequently induce the prophages to enter lytic cycles.The prophage-mediated lysis of the subpopulation resulted in an increased release of extracellular DNA and mem-brane vesicles that were conducive to Fe(III)oxide reduction,which might explain the positive role of prophages in ferrihydrite reduction.In summary,our results revealed the functional roles and underlying mechanisms of FRB-associated prophages in facilitating the dissimilatory reduction of Fe(III)oxides,which will advance our understanding of iron cycling in natural ecosystems.
