Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubat...Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubation with 15N isotope tracingwas conducted to explore millimeter-scale interactions of N and K on these pathways in soil fertilization zones.After 28 days,individual applications of N and K reduced denitrification-nitrogen removal rate(DNRR),anammox-nitrogen removal rate(ANRR),and feammox-nitrogen removal rate(FNRR)compared to a non-fertilizer control.N fertilizer had a greater effect than K,likely due to the high consumption of dissolved organic carbon by N fertilizer or the increased soil organic matter decomposition by K fertilizer.Combing of N and K increased DNRR,ANRR and FNRR rates by 31%,3090%and 244%compared to single N,and by-53.7%,885%and 222%compared to single K.These effects diminished with depth and distance from fertilizer sites.The effects of N fertilizer on these N removal processes might be regulate abundance of key microbes(e.g.,Limnobacter and Clostridium)and key gene(nirK,hzsB,ACM and Geo)by providing N substrates,while K enhances N metabolism efficiency through enzyme activation,indicated by the downregulation of certain genes(hzsB,ACM and Geo)and a negative correlation with N removal by simultaneously increasing gene expression and enzyme activity.These findings provide insights into how N and K together enhance N removal,emphasizing their importance for optimizing this process.展开更多
Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox i...Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox in river–estuary continuum is limited.In this study,stable isotope tracers and high-throughput amplicon sequencing were employed to determine Feammox rates and identify associated microbial communities in sediments along the Yangtze river–estuary continuum.Feammox rates averaged 0.0058±0.0069 mg N/(kg·d)and accounted for approximately 22.3%of the ammonium removed from the sediments.Sediment Fe(III),ammonium(NH_(4)^(+)),total organic carbon(TOC),and pH were identified as important factors influencing Feammox rates.Additionally,Spirochaeta,Caldilineaceae_uncultured,and Ignavibacterium were found potentially associated with Feammox,which had not been documented as Feammox-associated microbial taxa previously.This study demonstrates that Feammox plays a vital role in ammonium removal within the Yangtze river–estuary continuum,providing greater insight into nitrogen removal and cycling in aquatic ecosystems.展开更多
Ferric iron reduction coupled with anaerobic ammonium oxidation(Feammox)is a novel ferric-dependent autotrophic process for biological nitrogen removal(BNR)that has attracted increasing attention due to its low organi...Ferric iron reduction coupled with anaerobic ammonium oxidation(Feammox)is a novel ferric-dependent autotrophic process for biological nitrogen removal(BNR)that has attracted increasing attention due to its low organic carbon requirement.However,extracellular electron transfer limits the nitrogen transformation rate.In this study,activated carbon(AC)was used as an electron shuttle and added into an integrated autotrophic BNR system consisting of Feammox and anammox processes.The nitrogen removal performance,nitrogen transformation pathways and microbial communities were investigated during 194 days of operation.During the stable operational period(days 126–194),the total nitrogen(TN)removal efficiency reached 82.9%±6.8%with a nitrogen removal rate of 0.46±0.04 kg-TN/m^(3)/d.The contributions of the Feammox,anammox and heterotrophic denitrification pathways to TN loss accounted for 7.5%,89.5%and 3.0%,respectively.Batch experiments showed that AC was more effective in accelerating the Feammox rate than the anammox rate.X-ray photoelectron spectroscopy(XPS)analyses showed the presence of ferric iron(Fe(III))and ferrous iron(Fe(II))in secondary minerals.X-ray diffraction(XRD)patterns indicated that secondary iron species were formed on the surface of iron-AC carrier(Fe/AC),and Fe(III)was primarily reduced by ammonium in the Feammox process.The phyla Anaerolineaceae(0.542%)and Candidatus Magasanikbacteria(0.147%)might contribute to the Feammox process,and Candidatus Jettenia(2.10%)and Candidatus Brocadia(1.18%)were the dominative anammox phyla in the bioreactor.Overall,the addition of AC provided an effective way to enhance the autotrophic BNR process by integrating Feammox and anammox.展开更多
Elevated arsenic(As)mobilization and increased nitrous oxide(N_(2)O)emission are two primary environmental concerns existing in flooded paddy soils.In this study,dissolved As(Ⅲ),N isotope-labeled Na^(15)NO_(3),and/or...Elevated arsenic(As)mobilization and increased nitrous oxide(N_(2)O)emission are two primary environmental concerns existing in flooded paddy soils.In this study,dissolved As(Ⅲ),N isotope-labeled Na^(15)NO_(3),and/or^(14)NH_(4)Cl were incorporated into a microcosm incubation to determine the effects of N fertilization regimes on As mobilization and N_(2)O emission in a flooded paddy soil.Because nitrate had a higher redox potential and comprised a higher proportion of N substrate,As(Ⅴ)was preferentially formed due to enhanced nitrate-dependent microbial As(Ⅲ)oxidation.Thus,As availability was correspondingly attenuated due to the improved production of less mobile and toxic As(Ⅴ).After 2-d incubation,more than 90%and 98%of soluble As(Ⅲ)were immobilized in the As+NH_(4)^(+)-N+NO_(3)^(-)-N and As+NO_(3)^(-)-N treatments,respectively.Following nitrate depletion(after 2 d),microbial As(Ⅴ)and Fe(Ⅲ)reductions were gradually enhanced,which was attributed to stimulation of anaerobic ammonium oxidation(anammox)coupled to Fe(Ⅲ)reduction,known as Feammox,by the abundance of NH_(4)^(+).By the end of the incubation period(10 d),the As+NO_(3)^(-)-N treatment led to higher As immobilization of originally added As(Ⅲ)(ca.61%)than the As+NH_(4)^(+)-N+NO_(3)^(-)-N treatment(42%).The As+NH_(4)^(+)-N+NO_(3)^(-)-N treatment prominently mitigated N_(2)O emission compared to the As+NO_(3)^(-)-N treatment,which was ascribed to anammox,inducing accumulation of byproducts from incomplete denitrification.High-throughput sequencing indicated that the relative abundances of denitrifiers(e.g.,Azoarcus,Ochrobactrum,and Thiobacillus denitrificans)increased in the As+NO_(3)^(-)treatment,whereas quantitative polymerase chain reaction results indicated higher 16S rRNA gene copy numbers for anammox and Feammox(Acidimicrobiaceae bacterium A6)bacteria in the As+NH_(4)^(+)+NO_(3)^(-)treatment.Collectively,the experimental results demonstrated that N fertilization can be a feasible As remediation strategy while providing an effective strategy for mitigating N_(2)O emission from paddy soils at the same time.展开更多
基金supported by the National Natural Science Foundation of China(Nos.32271726 and 32171648)the Natural Science Foundation of Hubei Province of China(No.2022CFB030)。
文摘Soil denitrification,anammox,and Feammox are key for nitrogen(N)removal in agriculture.Despite potassium(K)fertilizer enhancing N efficiency,their role in regulation of these processes is unclear.A soil column incubation with 15N isotope tracingwas conducted to explore millimeter-scale interactions of N and K on these pathways in soil fertilization zones.After 28 days,individual applications of N and K reduced denitrification-nitrogen removal rate(DNRR),anammox-nitrogen removal rate(ANRR),and feammox-nitrogen removal rate(FNRR)compared to a non-fertilizer control.N fertilizer had a greater effect than K,likely due to the high consumption of dissolved organic carbon by N fertilizer or the increased soil organic matter decomposition by K fertilizer.Combing of N and K increased DNRR,ANRR and FNRR rates by 31%,3090%and 244%compared to single N,and by-53.7%,885%and 222%compared to single K.These effects diminished with depth and distance from fertilizer sites.The effects of N fertilizer on these N removal processes might be regulate abundance of key microbes(e.g.,Limnobacter and Clostridium)and key gene(nirK,hzsB,ACM and Geo)by providing N substrates,while K enhances N metabolism efficiency through enzyme activation,indicated by the downregulation of certain genes(hzsB,ACM and Geo)and a negative correlation with N removal by simultaneously increasing gene expression and enzyme activity.These findings provide insights into how N and K together enhance N removal,emphasizing their importance for optimizing this process.
基金supported by the National Natural Science Foundation of China(Nos.U2040201,32201334,92251304,and 42271126),the Project of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou,No.GML20220017),the Outstanding Postdoctoral Project in Jiangsu Province(No.2022ZB455),the Chinese Postdoctoral Science Foundation(No.2022M721661)and the Project of State Key Laboratory of Lake Science and Environment(No.2022SKL019).
文摘Anaerobic ammonium oxidation coupled to iron(III)reduction(Feammox)process has recently been recognized as an important pathway for removing ammonium in various natural habitats.However,our understanding for Feammox in river–estuary continuum is limited.In this study,stable isotope tracers and high-throughput amplicon sequencing were employed to determine Feammox rates and identify associated microbial communities in sediments along the Yangtze river–estuary continuum.Feammox rates averaged 0.0058±0.0069 mg N/(kg·d)and accounted for approximately 22.3%of the ammonium removed from the sediments.Sediment Fe(III),ammonium(NH_(4)^(+)),total organic carbon(TOC),and pH were identified as important factors influencing Feammox rates.Additionally,Spirochaeta,Caldilineaceae_uncultured,and Ignavibacterium were found potentially associated with Feammox,which had not been documented as Feammox-associated microbial taxa previously.This study demonstrates that Feammox plays a vital role in ammonium removal within the Yangtze river–estuary continuum,providing greater insight into nitrogen removal and cycling in aquatic ecosystems.
基金supported by the Key Research and Development Program of Guangdong Province(China)(No.2019B110205004)the Program for Guangdong Introducing Innovative and Entrepreneurial Teams(China)(No.2019ZT08L213)+1 种基金the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou,China)(No.GML2019ZD0403)the National Natural Science Foundation of China(Grant No.52000039).
文摘Ferric iron reduction coupled with anaerobic ammonium oxidation(Feammox)is a novel ferric-dependent autotrophic process for biological nitrogen removal(BNR)that has attracted increasing attention due to its low organic carbon requirement.However,extracellular electron transfer limits the nitrogen transformation rate.In this study,activated carbon(AC)was used as an electron shuttle and added into an integrated autotrophic BNR system consisting of Feammox and anammox processes.The nitrogen removal performance,nitrogen transformation pathways and microbial communities were investigated during 194 days of operation.During the stable operational period(days 126–194),the total nitrogen(TN)removal efficiency reached 82.9%±6.8%with a nitrogen removal rate of 0.46±0.04 kg-TN/m^(3)/d.The contributions of the Feammox,anammox and heterotrophic denitrification pathways to TN loss accounted for 7.5%,89.5%and 3.0%,respectively.Batch experiments showed that AC was more effective in accelerating the Feammox rate than the anammox rate.X-ray photoelectron spectroscopy(XPS)analyses showed the presence of ferric iron(Fe(III))and ferrous iron(Fe(II))in secondary minerals.X-ray diffraction(XRD)patterns indicated that secondary iron species were formed on the surface of iron-AC carrier(Fe/AC),and Fe(III)was primarily reduced by ammonium in the Feammox process.The phyla Anaerolineaceae(0.542%)and Candidatus Magasanikbacteria(0.147%)might contribute to the Feammox process,and Candidatus Jettenia(2.10%)and Candidatus Brocadia(1.18%)were the dominative anammox phyla in the bioreactor.Overall,the addition of AC provided an effective way to enhance the autotrophic BNR process by integrating Feammox and anammox.
基金supported by the National Natural Science Foundation of China(No.41807035)the Public Welfare Technology Application Research Project of Zhejiang Province,China(No.LGF22E080002)+3 种基金the Higher Education Institution Scientific Research Project of Ningxia,China(No.NYG2024118)the Natural Science Foundation of Ningxia,China(No.2024AAC05063)the Natural Science Foundation of Xiamen,China(No.3502Z20227321)the Municipal Science and Technology Bureau of Wenzhou,China(Nos.X20210033 and X20210096)。
文摘Elevated arsenic(As)mobilization and increased nitrous oxide(N_(2)O)emission are two primary environmental concerns existing in flooded paddy soils.In this study,dissolved As(Ⅲ),N isotope-labeled Na^(15)NO_(3),and/or^(14)NH_(4)Cl were incorporated into a microcosm incubation to determine the effects of N fertilization regimes on As mobilization and N_(2)O emission in a flooded paddy soil.Because nitrate had a higher redox potential and comprised a higher proportion of N substrate,As(Ⅴ)was preferentially formed due to enhanced nitrate-dependent microbial As(Ⅲ)oxidation.Thus,As availability was correspondingly attenuated due to the improved production of less mobile and toxic As(Ⅴ).After 2-d incubation,more than 90%and 98%of soluble As(Ⅲ)were immobilized in the As+NH_(4)^(+)-N+NO_(3)^(-)-N and As+NO_(3)^(-)-N treatments,respectively.Following nitrate depletion(after 2 d),microbial As(Ⅴ)and Fe(Ⅲ)reductions were gradually enhanced,which was attributed to stimulation of anaerobic ammonium oxidation(anammox)coupled to Fe(Ⅲ)reduction,known as Feammox,by the abundance of NH_(4)^(+).By the end of the incubation period(10 d),the As+NO_(3)^(-)-N treatment led to higher As immobilization of originally added As(Ⅲ)(ca.61%)than the As+NH_(4)^(+)-N+NO_(3)^(-)-N treatment(42%).The As+NH_(4)^(+)-N+NO_(3)^(-)-N treatment prominently mitigated N_(2)O emission compared to the As+NO_(3)^(-)-N treatment,which was ascribed to anammox,inducing accumulation of byproducts from incomplete denitrification.High-throughput sequencing indicated that the relative abundances of denitrifiers(e.g.,Azoarcus,Ochrobactrum,and Thiobacillus denitrificans)increased in the As+NO_(3)^(-)treatment,whereas quantitative polymerase chain reaction results indicated higher 16S rRNA gene copy numbers for anammox and Feammox(Acidimicrobiaceae bacterium A6)bacteria in the As+NH_(4)^(+)+NO_(3)^(-)treatment.Collectively,the experimental results demonstrated that N fertilization can be a feasible As remediation strategy while providing an effective strategy for mitigating N_(2)O emission from paddy soils at the same time.
