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| Measurement of denitrification, Anammox, DNRA rates, and net N2 flux in paddy soil using a membrane inlet mass spectrometer |
| Received:December 28, 2018 |
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| KeyWord:paddy soil;15N tracer;denitrification;Anammox;DNRA |
| Author Name | Affiliation | E-mail | | LI Jin-fang | 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 | | | CHAI Yan-chao | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | | | CHEN Shun-tao | State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
China Pharmaceutical University, Nanjing 210009, China | | | SHAN Jun | 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 | shanjun@issas.ac.cn | | YAN Xiao-yuan | 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 | |
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| Abstract: |
| Denitrification, anaerobic ammonium oxidation(Anammox), and dissimilatory nitrate reduction to ammonium(DNRA)are the three nitrate reduction processes that largely control the fate of chemical N fertilizers in flooded rice paddies. Previous studies related to the nitrate reduction process mainly focused on one or two independent processes(e.g., denitrification and Anammox), whereas a simultaneous investigation of denitrification, Anammox, and DNRA and their relative contributions to total nitrate removal is lacking. Because of methodological limitations, the near in situ measurement of net N2 flux is also rare. In this study, using membrane inlet mass spectrometry(MIMS) combined with laboratory soil slurry-based 15N tracer and soil core incubation-based N2/Ar techniques, denitrification, Anammox, DNRA,and net N2 flux were investigated in five paddy soils collected from different rice regions of China(Yingkou, YK; Yixing, YX; Jinhua, JH; Guilin, GL; Guangan, GA). The measured rates of denitrification, Anammox, DNRA, and net N2 flux across all paddy soils were(358.63±25.37)~(479.96±22.12),(-14.81±0.22)~(5.29±1.22)(, 25.76±12.71)~(109.87±3.88), and(33.33±11.16)~(72.74±14.18)g N·hm-2·h-1, respectively, which were comparable with previous studies. The soil NO3-, DOC(dissolved organic carbon), and Fe2+ contents were the three dominating factors affecting denitrification. By comparison, the Anammox rates only correlated with the soil NO3- content, whereas the DNRA rates closely related to the soil DOC and Fe2+ content. These results demonstrate that the MIMS combined with laboratory soil slurry-based 15N tracer and soil core incubation-based N2/Ar techniques is a viable, rapid, and precise method for the measurement of denitrification, Anammox, DNRA rates, and net N2 flux in flooded paddy soil, with an obvious advantage that a smaller sample size is required for determination compared to other methods. |
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