摘要
氧化亚氮(N_(2)O)是导致全球气候变化的重要温室气体之一,植物根际微生物介导的反硝化和厌氧氨氧化过程作为重要脱氮途径能够减少湖泊湿地生态系统中氮负荷,而反硝化过程是N_(2)O的最主要产生途径.城市湖泊湖滨带是水陆交错带,也是氮素输入和转化的重要区域,关注城市湖泊湖滨带植物-微生物介导的脱氮过程和N_(2)O排放,对维持湖泊生态系统稳定,加强城市湖泊湿地的氮素管理和控制N_(2)O排放,实现城市可持续发展具有重要意义.以典型城市湖泊玄武湖湖滨带为研究对象,结合^(15)N同位素配对、实时荧光定量PCR和高通量测序技术,比较不同类型湿地植物:莲(Nelumbo nucifera)、芦苇(Phragmites australis)和马蹄金(Dichondra micrantha)覆盖区原位N_(2)O排放通量、潜在反硝化及厌氧氨氧化速率和功能微生物群落丰度、多样性及组成,探讨城市湖泊湿地不同类型植物-微生物介导的脱氮过程及N_(2)O排放的驱动因子.结果表明,玄武湖湖滨带湿地植物区N_(2)O排放通量为6.20~15.03μg·(m^(2)·h)^(−1),其中马蹄金>莲>芦苇;3种湿地植物根际沉积物反硝化和厌氧氨氧化速率(以N计)分别为(8.92±4.33)nmol·(g·h)^(−1)和(1.03±1.17)nmol·(g·h)^(−1),其中莲>马蹄金>芦苇,并且反硝化作用(65.55%~97.82%)均为主导脱氮过程;3种湿地植物根际沉积物中nirK和nirS群落组成存在显著差异(ANOSIM,P<0.005),硝化杆菌科(Nitrobacteraceae,28.57%)和食球菌科(Zoogloeaceae,14.63%)分别为nirK和nirS群落中优势科,并且nirS基因丰度(1.09×10^(9)copies·g^(−1))比nirK(3.00×10^(7)copies·g^(−1))高2个数量级,表明nirS型反硝化菌在湿地N_(2)O排放中更具重要作用(P<0.05);此外,pH、C/N、NH_(4)^(+)-N和NO_(3)^(−)-N含量驱动了玄武湖湖滨带N_(2)O排放通量的变化,而NO_(2)^(−)-N、LOI和TN含量是玄武湖湖滨带潜在反硝化和厌氧氨氧化速率的主要驱动因子.
Nitrous oxide(N_(2)O)is one of the important greenhouse gases contributing to the global warming trend.As important nitrogen removal pathways,microbially mediated denitrification and anaerobic ammonia oxidation(ANAMMOX)in the rhizospheres of wetland plants can reduce nitrogen load in freshwater wetlands,and the denitrification process is the major N_(2)O source.Littoral zone of urban lakes is an ecotone between terrestrial and aquatic ecosystems and an important area for nitrogen input and transformation.The investigation of plant-microbially mediated nitrogen removal processes and N_(2)O emissions in the littoral zone of urban lakes is of great significance for maintaining the stability of lake ecosystems,strengthening nitrogen management,and controlling N_(2)O emission,as well as realizing sustainable urban development.In this study,the littoral zone of Xuanwu Lake(a typical urban lake in Nanjing)was selected to compare the in situ N_(2)O emission fluxes,potential denitrification and ANAMMOX rates,as well as the abundance,diversity,and composition of functional microbial communities associated with three dominant plants(i.e.,Nelumbo nucifera,Phragmites australis,and Dichondra micrantha)using ^(15)N isotope pairing,real-time quantitative PCR,and high-throughput sequencing techniques.In addition,the influences of different driving factors on the potential denitrification and ANAMMOX rates and N_(2)O fluxes were further explored in the littoral zone.The results showed that the N_(2)O emission fluxes in the littoral zone of Xuanwu Lake ranged from 6.20 to 15.03μg·(m^(2)·h)^(−1)(D.micrantha>N.nucifera>P.australis).Potential denitrification and ANAMMOX rates in the rhizosphere sediments of the three wetland plants were(8.92±4.33)nmol·(g·h)^(−1)and(1.03±1.17)nmol·(g·h)^(−1),respectively(N.nucifera>D.micrantha>P.australis),and denitrification(65.55%-97.82%)was the dominant nitrogen removal process.There were significant differences in the community composition of nirK and nirS in rhizosphere sediments of the three wetland plants(ANOSIM,P<0.005),and Nitrobacteraceae(28.57%)and Zoogloeaceae(14.63%)were the dominant families in the nirK and nirS communities.The abundances of the nirS gene(1.09×10^(9)copies·g^(−1))were 2 orders of magnitude higher than those of the nirK gene(3.00×10^(7)copies·g^(−1)),indicating that nirS-denitrifier played a more important role in N_(2)O emission(P<0.05).Moreover,pH,C/N,NH_(4)^(+)-N,and NO_(3)^(−)-N contents drove the changes of N_(2)O fluxes,while NO_(2)^(−)-N,LOI,and TN contents were the main regulators of potential denitrification and ANAMMOX rates in the littoral zone of Xuanwu Lake.
作者
孙丽杰
苏芮
何肖微
李启升
黄睿
曾巾
赵大勇
SUN Li-jie;SU Rui;HE Xiao-wei;LI Qi-sheng;HUANG Rui;ZENG Jin;ZHAO Da-yong(National Key Laboratory of Water Disaster Prevention,Hohai University,Nanjing 210098,China;College of Hydrology and Water Resources,Hohai University,Nanjing 210098,China;Key Laboratory of Lake and Basin Water Safty,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 211135,China;State Key Laboratory of Lake Science and Environment,Nanjing Institute of Geography and Limnology,Chinese Academy of Sciences,Nanjing 211135,China;Jiangsu Hydraulic Research Institute,Nanjing 210017,China;College of Geography and Remote Sensing,Hohai University,Nanjing 211000,China)
出处
《环境科学》
北大核心
2025年第7期4322-4334,共13页
Environmental Science
基金
国家自然科学基金项目(92351303,U23A20153,32171563,42207303)
江苏省碳达峰碳中和科技创新专项(BK20220015)。
