水稻土Fe^(2+)氧化耦合硝酸根异化还原成铵(DNRA)及其对氧气存在和碳源添加的响应  

Dissimilatory Nitrate Reduction to Ammonium Coupled to Fe;Oxidation in Paddy Soils as Affected by Oxygen Presence and Carbon Addition

作　　者：吴敏 李进芳[1,2] 魏志军 李承霖 夏永秋 单军[1,3] 颜晓元 WU Min;LI Jinfang;WEI Zhijun;LI Chenglin;XIA Yongqiu;SHAN Jun;YAN Xiaoyuan(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China;Changshu Agro-ecological Experimental Station,Chinese Academy of Sciences,Changshu,Jiangsu 215555,China)

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049 [3]中国科学院常熟农业生态实验站,江苏常熟215555

出　　处：《土壤学报》2022年第1期253-262,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金项目(41571289);国家重点研发计划项目(2017YFD0200101)资助。

摘　　要：以江苏常熟和湖南桃源水稻土为研究对象,通过室内15N示踪实验研究水稻土中Fe^(2+)氧化耦合硝酸根异化还原成铵(Dissimilatory nitrate reduction to ammonium,DNRA)过程及其对氧气存在和碳源添加的响应。结果表明,两种水稻土中均存在Fe^(2+)氧化耦合DNRA过程,常熟和桃源水稻土中DNRA的速率分别为0.38±0.15和0.36±0.21nmol·g^(-1)·h^(-1)(以N计),当体系中Fe^(2+)浓度为500μmol·L^(-1)时,DNRA速率有所提升但并不显著,当Fe^(2+)浓度为800μmol·L^(-1)时,DNRA速率提升显著(P <0.05),分别提升至2.35±0.30和0.81±0.22 nmol·g^(-1)·h^(-1)。在800μmol·L^(-1)Fe^(2+)浓度下,常熟水稻土中Fe^(2+)氧化耦合DNRA的速率显著(P <0.05)高于桃源水稻土,与两种水稻土中nrfA功能基因丰度的高低一致。在氧气存在和碳源添加的响应实验中,单一氧气处理、单一乳酸处理及氧气乳酸联合处理均显著(P <0.05)促进桃源水稻土Fe^(2+)氧化耦合DNRA过程速率,而在常熟水稻土中,800μmol·L^(-1)Fe^(2+)浓度下,单一乳酸及乳酸氧气联合处理显著(P <0.05)抑制Fe^(2+)氧化耦合DNRA过程速率。以上研究表明,两种水稻土中均存在Fe^(2+)氧化耦合DNRA过程,氧气和乳酸的单独、联合作用可以影响Fe^(2+)耦合DNRA过程,但具体影响因土壤而异。未来研究还应纳入更多土壤样本,综合考虑环境因子和土壤性质对Fe^(2+)氧化耦合DNRA过程的影响。【Objective】Dissimilatory nitrate reduction to ammonium(DNRA), a biological pathway converting NO;to NH;,provides ammonium for rice uptake and microbial immobilization, resulting in N retention in paddy soils. Recently, the coupling between DNRA and Fe^(2+) oxidation has been reported occurring in freshwater lake or estuary sediments. However, so far little has been reported on this process in paddy soil, and its potential key factors are practically unknown. 【Method】Using 15 N-tracing technique in combination with membrane inlet mass spectrometer(MIMS), an in-lab incubation experiment was performed to investigate the process of DNRA coupled to Fe^(2+) oxidation as affected by oxygen presence and carbon addition in two types of paddy soils(CS and TY). 【Result】Results showed that the process of DNRA coupled to Fe^(2+) oxidation was found in both paddy soils, where the potential rate of DNRA increased from N 0.36–0.38 to 0.81–2.35 nmol·g^(-1)·h^(-1)with Fe^(2+)addition rising from 0 to 800 μmol·L^(-1). At the concentration of 800 μmol·L^(-1)Fe^(2+), potential rate of DNRA was significantly higher in CS soil than that in TY soil, which was in consistence with differences of nrfA gene abundance between the two tested soils. Effect of oxygen presence and/or lactic acid addition on the process of DNRA coupled to Fe^(2+)oxidation varied in the two tested paddy soils. In TY soil, regardless of singly or in combination applied, oxygen presence and lactic acid addition significantly promoted potential rate of DNRA at varying Fe^(2+)concentrations. In CS soil, single oxygen presence or lactic acid addition significantly increased potential rate of DNRA at the concentration of 500 μmol·L^(-1)Fe^(2+), whereas, at the concentration of 800 μmol·L^(-1)Fe^(2+), either lactic acid singly applied or in combination with oxygen significantly decreased potential rate of DNRA. 【Conclusion】 Findings of this study suggest that the process of DNRA coupled to Fe^(2+)oxidation occurs in paddy soils and may be af

关 键 词：硝酸根异化还原 亚铁氧化 碳源 氧气 N同位素示踪 

分 类 号：S19[农业科学—农业基础科学]