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| Estimating the denitrification rate of water bodies by gas diffusion coefficient method |
| Received:August 02, 2022 |
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| KeyWord:denitrification rate;gas diffusion coefficient method;MIMS-based method;Michaelis-Menten equation;sensitivity analysis |
| Author Name | Affiliation | E-mail | | LI Xiaohan | State Key Laboratory of Soil & Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | YAN Xing | State Key Laboratory of Soil & Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
University of Chinese Academy of Sciences, Beijing 100049, China | | | XIA Yongqiu | State Key Laboratory of Soil & Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | yqxia@issas.ac.cn | | YAN Xiaoyuan | State Key Laboratory of Soil & Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China | |
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| Abstract: |
| Although the gas diffusion coefficient method based on the empirical coefficient or mechanism process has been developed for simple and accurate denitrification estimation in recent years, little is known about its reliability, applicability, and uncertainty. In this study, a membrane inlet mass spectrometer(MIMS) -based method and the gas-diffusion coefficient method were compared in static water bodies under different nitrate concentrations(0, 1, 2, 4 mg · L-1, and 6 mg · L-1, calculated by N). Results showed that the relationship between nitrate concentration and denitrification rates estimated by the three gas diffusion coefficient methods(BO04, CL07 and Xia21 models) followed the Michaelis-Menten equation(R2=0.994 6, P<0.01). There was a significant linear relationship between the denitrification rates estimated by the three gas diffusion coefficient methods and the MIMS-based method(R2=0.776 7, P<0.05), although with a different slope. Among the three gas diffusion coefficient methods, the CL07 and Xia21 models were more reliable according to the slopes of the measurements from the MIMS-based method, with slopes of 1.22 and 0.59, respectively. Taking the CL07 model as an example, Monte Carlo analysis revealed that wind speed, water flow velocity, and water temperature were the three most sensitive factors, with unbiased percent difference(UPD) of 12.13%, 9.49%, and 9.42%, respectively. In conclusion, this study shows that the gas diffusion coefficient method can accurately estimate the denitrification rate of water bodies, providing a methodological basis for large-scale in-situ denitrification estimation and nitrogen cycling studies. We also emphasize the necessity of selecting and calibrating the gas diffusion coefficient model based on local environmental conditions. |
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