Dissimilarity nitrate reduction to ammonium(DNRA)is of significance in agriculture ecosystems as the process is beneficial to N retention in soils.However,how fertilization regimes influence DNRA rates and functional ...Dissimilarity nitrate reduction to ammonium(DNRA)is of significance in agriculture ecosystems as the process is beneficial to N retention in soils.However,how fertilization regimes influence DNRA rates and functional microbes in agriculture was rarely estimated.In the present study,a 2-year pot experiment was conducted in two contrasting paddy soils to evaluate the effects of straw and nitrogen addition on DNRA process and the related functional microbes,using stable isotope tracer and molecular ecology techniques.The results showed that the abundance and transcription activity of nitrite reductase encoding gene(nrfA)involved in DNRA process and DNRA rates were significantly higher in alkaline soils than in acidic soils.Straw incorporation significantly enhanced nrfA gene abundance and transcription activity,with a greater effect in alkaline soil than in acidic soil.The rates of DNRA,abundance and transcription activity of nrfA gene positively correlated to soil C/N and C/NO_(3)^(-) induced by straw application.Sequencing analysis based on nrfA gene transcript showed that Deltaproteobacteria was the most dominant group in both soil types(30.9%-67.4%),while Gammaproteobacteria,Chloroflexi,Actinobacteria were selectively enriched by straw incorporation.These results demonstrated that DNRA activity can be improved by straw return practice in paddy soils while the effect will vary among soil types due to differentiated functional microbial communities and edaphic properties.展开更多
试验以模拟生物滞留系统为研究对象,运用^(15)N同位素示踪技术研究土壤不同氧化还原电位(Eh)和p H条件下硝酸盐异化还原为氨(DNRA)作用对氮的去除效果。结果表明:在土壤Eh为225~100 m V、0^-120 m V和-225^-340 m V条件下,随着Eh的降低...试验以模拟生物滞留系统为研究对象,运用^(15)N同位素示踪技术研究土壤不同氧化还原电位(Eh)和p H条件下硝酸盐异化还原为氨(DNRA)作用对氮的去除效果。结果表明:在土壤Eh为225~100 m V、0^-120 m V和-225^-340 m V条件下,随着Eh的降低,硝酸盐异化还原为氨(DNRA)作用增强;生物滞留系统中同时存在反硝化反应和DNRA作用,在0^-120 m V区间,更有利于反硝化作用的发生;在-225^-340 m V区间,更有利于DNRA作用的发生;生物滞留系统土壤p H为5~7的条件下,DNRA作用效果随着p H的增加而增强;在p H为7~9时,DNRA作用效果随着p H的增加而减弱;表明DNRA作用易在中性偏碱性的环境下发生。展开更多
反硝化(Denitrification,DNF)和硝酸盐异化还原为氨(Dissimilatory Nitrate Reduction to Ammonium,DNRA)是硝酸盐异养还原的2个主要途径.反硝化被认为是彻底去除水体氮负荷的主要过程;而硝酸盐异化还原为氨则将水体中的硝态氮转化为氨...反硝化(Denitrification,DNF)和硝酸盐异化还原为氨(Dissimilatory Nitrate Reduction to Ammonium,DNRA)是硝酸盐异养还原的2个主要途径.反硝化被认为是彻底去除水体氮负荷的主要过程;而硝酸盐异化还原为氨则将水体中的硝态氮转化为氨氮.2个过程均以硝酸盐为电子受体,并存在相互竞争关系.这2个过程的研究对理解湿地氮转化以及指导湿地氮污染修复具有重要意义.运用无扰动沉积物柱样流动培养、15NO-3-N同位素示踪实验,并采用氨氧化-膜接口质谱仪联用(OX/MIMS)测定氨氮同位素产物的方法,对鄱阳湖碟形湖湿地、巢湖重污染河流湿地、巢湖重污染湖泊湿地3种类型湿地沉积物-水界面的硝酸盐异养还原过程进行研究,结果表明存在显著差异.3种类型湿地DNF速率的范围为(6.36±2.57)^(99.98±14.05)μmol/(m2·h),DNRA速率的范围为(0.51±0.45)^(79.82±6.08)μmol/(m2·h).在3种类型湿地中,随着氮污染程度加重,DNF和DNRA速率均显著增加,且DNRA过程在总的硝态氮异养还原中所占的比重不断增大,说明较高的硝酸盐负荷、较高的沉积物有机质含量更有利于DNRA过程的竞争.而对反硝化方式的进一步研究发现,巢湖重污染河流、湖泊湿地主要以非耦合反硝化为主导过程,而鄱阳湖碟形湖湿地则更倾向于以硝化过程耦合控制的反硝化为主.展开更多
基金financially supported by the National Natural Science Foundation of China(41771288)National Key Research and Development Program(2017YFE0109800)supported by the Youth Innovation Promotion Association(2012031),Chinese Academy of Sciences.
文摘Dissimilarity nitrate reduction to ammonium(DNRA)is of significance in agriculture ecosystems as the process is beneficial to N retention in soils.However,how fertilization regimes influence DNRA rates and functional microbes in agriculture was rarely estimated.In the present study,a 2-year pot experiment was conducted in two contrasting paddy soils to evaluate the effects of straw and nitrogen addition on DNRA process and the related functional microbes,using stable isotope tracer and molecular ecology techniques.The results showed that the abundance and transcription activity of nitrite reductase encoding gene(nrfA)involved in DNRA process and DNRA rates were significantly higher in alkaline soils than in acidic soils.Straw incorporation significantly enhanced nrfA gene abundance and transcription activity,with a greater effect in alkaline soil than in acidic soil.The rates of DNRA,abundance and transcription activity of nrfA gene positively correlated to soil C/N and C/NO_(3)^(-) induced by straw application.Sequencing analysis based on nrfA gene transcript showed that Deltaproteobacteria was the most dominant group in both soil types(30.9%-67.4%),while Gammaproteobacteria,Chloroflexi,Actinobacteria were selectively enriched by straw incorporation.These results demonstrated that DNRA activity can be improved by straw return practice in paddy soils while the effect will vary among soil types due to differentiated functional microbial communities and edaphic properties.
文摘试验以模拟生物滞留系统为研究对象,运用^(15)N同位素示踪技术研究土壤不同氧化还原电位(Eh)和p H条件下硝酸盐异化还原为氨(DNRA)作用对氮的去除效果。结果表明:在土壤Eh为225~100 m V、0^-120 m V和-225^-340 m V条件下,随着Eh的降低,硝酸盐异化还原为氨(DNRA)作用增强;生物滞留系统中同时存在反硝化反应和DNRA作用,在0^-120 m V区间,更有利于反硝化作用的发生;在-225^-340 m V区间,更有利于DNRA作用的发生;生物滞留系统土壤p H为5~7的条件下,DNRA作用效果随着p H的增加而增强;在p H为7~9时,DNRA作用效果随着p H的增加而减弱;表明DNRA作用易在中性偏碱性的环境下发生。
文摘反硝化(Denitrification,DNF)和硝酸盐异化还原为氨(Dissimilatory Nitrate Reduction to Ammonium,DNRA)是硝酸盐异养还原的2个主要途径.反硝化被认为是彻底去除水体氮负荷的主要过程;而硝酸盐异化还原为氨则将水体中的硝态氮转化为氨氮.2个过程均以硝酸盐为电子受体,并存在相互竞争关系.这2个过程的研究对理解湿地氮转化以及指导湿地氮污染修复具有重要意义.运用无扰动沉积物柱样流动培养、15NO-3-N同位素示踪实验,并采用氨氧化-膜接口质谱仪联用(OX/MIMS)测定氨氮同位素产物的方法,对鄱阳湖碟形湖湿地、巢湖重污染河流湿地、巢湖重污染湖泊湿地3种类型湿地沉积物-水界面的硝酸盐异养还原过程进行研究,结果表明存在显著差异.3种类型湿地DNF速率的范围为(6.36±2.57)^(99.98±14.05)μmol/(m2·h),DNRA速率的范围为(0.51±0.45)^(79.82±6.08)μmol/(m2·h).在3种类型湿地中,随着氮污染程度加重,DNF和DNRA速率均显著增加,且DNRA过程在总的硝态氮异养还原中所占的比重不断增大,说明较高的硝酸盐负荷、较高的沉积物有机质含量更有利于DNRA过程的竞争.而对反硝化方式的进一步研究发现,巢湖重污染河流、湖泊湿地主要以非耦合反硝化为主导过程,而鄱阳湖碟形湖湿地则更倾向于以硝化过程耦合控制的反硝化为主.
