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| Coupling process of CH4 and N2O double reduction in the Chongming Dongtan Wetland,China |
| Received:July 30, 2023 |
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| KeyWord:coastal wetland;anaerobic CH4 oxidation;N2O reduction;coupling reaction;mcrA;nosZ Ⅱ |
| Author Name | Affiliation | E-mail | | CHEN Han | School of Applied Meteorology/Jiangsu Provincial Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | RAO Xudong | School of Applied Meteorology/Jiangsu Provincial Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China | | | TENG Zhaojun | School of Applied Meteorology/Jiangsu Provincial Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | ZHANG Yaohong | School of Applied Meteorology/Jiangsu Provincial Key Laboratory of Agricultural Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China | yhzhang@nuist.edu.cn | | JIA Zhongjun | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | |
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| Abstract: |
| Anaerobic oxidation of methane (AOM) driven by N2O reduction is a new pathway for greenhouse gas reduction in wetland systems; however the effect on paddy field utilization after the reclamation of coastal natural wetland using this pathway is unclear. In this study, three experimental treatments (13CH4, 13CH4+N2O, and N2O) were set up for anaerobic incubation of natural coastal wetlands (bare wetlands and reed wetlands) and reclaimed rice fields(19 and 86 years of rice cultivation) in the Chongming Dongtan Natural Wetland in the Yangtze River Estuary. Stable isotope labelling combined with quantitative PCR was used to analyze AOM rates driven by N2O reduction and its carbon sequestration potential in different wetland soils, and to study the quantitative characteristics of their related functional genes. The rates of CH4 anaerobic oxidation driven by N2O reduction in the reclaimed paddy fields ranged from 6.10 ng·g-1·d-1 to 7.51 ng·g-1·d-1, much higher than those in natural marsh wetlands. The sequestered organic carbon (13C-SOC) derived from anaerobic CH4 oxidation driven by N2O reduction was 18.1-49.4 nmol·g-1, indicating the strong carbon sequestration potential of the process. For nitrateand sulfate-dependent anaerobic CH4-oxidizing archaea in the tested soils, mcrA numbers under 13CH4+N2O addition conditions ranged from (1.08-2.29)×107 copies·g-1 and(2.55-14.30)×107 copies·g-1, which were 25.8%-64.1% and 41.0%-50.1% higher than those under 13CH4 treatment, respectively. In contrast, pmoA numbers of nitrite-dependent CH4 anaerobic oxidizing bacteria did not change significantly between the two addition treatments. Correlation analysis revealed that N2O-dependent AOM rates were significantly and positively correlated with both nosZ Ⅱ and the nitrate-dependent mcrA numbers, suggesting that nosZ Ⅱ N2O-reducing microorganisms and nitrate-dependent anaerobic CH4-oxidizing archaea may jointly participate in the coupling reaction of anaerobic CH4 oxidation and N2O reduction, whereas sulfate-dependent anaerobic CH4-oxidizing archaea play an important role in natural coastal wetlands. In conclusion, the reclamation of coastal wetlands into paddy fields promotes the N2O-driven anaerobic CH4 oxidation process, which makes a remarkably positive contribution to the dual reduction of CH4 and N2O in coastal wetlands. |
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