Sun Xiaoying, Tong Juxiu, Liu Cong, Ma Yanbao
School of Water Resources & Environment, China University of Geosciences, Beijing, People's Republic of China, 100083.
MOE Key Laboratory of Groundwater Circulation and Environmental Evolution, China University of Geosciences, Beijing, People's Republic of China, 100083.
Environ Sci Pollut Res Int. 2022 May;29(22):32894-32912. doi: 10.1007/s11356-021-18457-4. Epub 2022 Jan 12.
In recent years, agricultural non-point source pollution (ANPSP) has become increasingly prominent, and nitrogen plays an important role in ANPSP. Therefore, we carried out traditional flooded irrigation (TFI) experiments in the paddy field, and applied HYDRUS-2D model to simulate the nitrogen transport in this study. Three observation points A1, A2, and A3 were arranged on the diagonal of the paddy field. We observed ponding water depth on soil surface and nitrogen concentrations in ponding water and soil water at 0.1 m, 0.2 m, and 0.3 m below soil surface. HYDRUS-2D model was proved to be effective in simulating the ponding water depth with root mean squared error (RMSE) = 0.717 cm and Nash-Sutcliffe coefficient (NSE) = 0.805 for the simulated and measured ponding water depth. The simulated and measured NH-N concentrations at different depths below soil surface at point A1 basically had the same trend, and the simulated NH-N concentrations in ponding water had better agreement with the measured data with RMSE = 1.323 mg/L, and NSE = 0.958. The measured NH-N concentrations at depths of 0.1 m, 0.2 m, and 0.3 m below soil surface at point A2 were larger than the simulated values, but they had the same trend on the whole. The simulated NH-N concentrations at different depths below soils' surface at point A3 did not fit well with the measured values. The overall trend of the simulated and measured NO-N concentrations in ponding water on soil surface at point A1 was consistent, but the peak values of the simulated NO-N concentrations were larger than the measured ones. The simulated and measured NO-N concentrations at different depths below soil surface at points A2 and A3 did not agree well although they had the same trend, which became worse with the increase of soil depth. This indicated that the HYDRUS-2D model was effective in simulating water flow and nitrogen transport in TFI paddy fields. Sensitivity analysis suggested different simulated nitrogen concentrations in different water depths at different time were sensitive to different model parameters.
近年来，农业面源污染日益突出，氮在农业面源污染中起着重要作用。因此，本研究在稻田开展了传统淹灌试验，并应用HYDRUS-2D模型模拟氮素运移。在稻田对角线上布置了A1、A2和A3三个观测点。观测了土壤表面的积水深度以及土壤表面以下0.1 m、0.2 m和0.3 m处积水和土壤水中的氮浓度。结果表明，HYDRUS-2D模型在模拟积水深度方面是有效的，模拟积水深度与实测值的均方根误差（RMSE）=0.717 cm，纳什-萨特克利夫系数（NSE）=0.805。A1点土壤表面以下不同深度处模拟和实测的NH-N浓度基本趋势相同，模拟积水水中的NH-N浓度与实测数据吻合较好，RMSE=1.323 mg/L，NSE=0.958。A2点土壤表面以下0.1 m、0.2 m和0.3 m深度处实测的NH-N浓度大于模拟值，但总体趋势相同。A3点土壤表面以下不同深度处模拟的NH-N浓度与实测值拟合效果不佳。A1点土壤表面积水水中模拟和实测的NO-N浓度总体趋势一致，但模拟的NO-N浓度峰值大于实测值。A2和A3点土壤表面以下不同深度处模拟和实测的NO-N浓度虽趋势相同但吻合度不佳，且随土壤深度增加而变差。这表明HYDRUS-2D模型在模拟传统淹灌稻田水流和氮素运移方面是有效的。敏感性分析表明，不同时间不同水深下模拟的氮浓度对不同模型参数敏感。
