Chen Cheng-Long, Gao Ming, Ni Jiu-Pai, Xie De-Ti, Deng Hua
College of Resources and Environment, Southwest University, Chongqing 400715, China.
Chongqing Engineering Research Center for Agricultural Non-point Source Pollution Control in the Three Gorges Reservoir Area, Chongqing 400715, China.
Huan Jing Ke Xue. 2017 May 8;38(5):1889-1897. doi: 10.13227/j.hjkx.201606042.
This paper used three plots of paddy field in Wangjiagou small catchment in Fuling District, Chongqing Municipality as a case study. Wangjiagou, located in Three Gorges Reservoir Area, provided a good case in terms of its closeness of surface runoff. The samples of individual rainfall of twelve times and process of two typical individual rainfalls on three plots of sloping paddy field were collected from 2014 to 2015. These samples were used to analyze the influence of spatial pattern of sloping paddy field on the concentration of nitrogen and phosphorus in the surface runoff. The samples of daily runoff in subcatchments in 2010 and 2015 were used to analyze the influence of spatial pattern change of subcatchments' paddy field on the concentration of nitrogen and phosphorus in the surface runoff. The results indicated that the removal rates of TN, NO-N and TP of paddy field at the valley bottom were higher than those in the mid-slopes. The removal rate of TP would be higher if plot size of paddy field at the bottom got bigger. During individual rainfall event, the losses concentration of TN, NO-N and TP in the paddy fields was significantly different among three different spatial patterns during the previous period of heavy rain event, but it became different during the next period of moderate rain event. The two subcatchments' spatial pattern change of paddy field had weakened the intercepting purification ability of nitrogen and phosphorus losses of paddy field in 2015, compared with that in 2010. TN's losses concentration increased significantly during the periods of light and moderate rain event and base flow. TP's losses concentration fluctuated during the event from moderate rain to heavy rain. Hence, increasing the area of paddy field of catchment and optimizing its spatial pattern reasonably were found as effective measures to control agricultural non-point source pollution in the Three Gorges Reservoir Region.
本文以重庆市涪陵区王家沟小流域的三块稻田为案例进行研究。王家沟位于三峡库区，因其地表径流情况相近，提供了一个很好的案例。于2014年至2015年收集了三块坡耕地稻田12次单独降雨的样本以及两次典型单独降雨过程的样本，用于分析坡耕地稻田空间格局对地表径流中氮磷浓度的影响。利用2010年和2015年子流域日径流样本，分析子流域稻田空间格局变化对地表径流中氮磷浓度的影响。结果表明，谷底稻田总氮（TN）、硝态氮（NO-N）和总磷（TP）的去除率高于坡中稻田。谷底稻田地块面积越大，TP去除率越高。在单次降雨事件中，大雨前期，三种不同空间格局的稻田中TN、NO-N和TP的流失浓度存在显著差异，但在随后的中雨期则有所不同。与2010年相比，2015年两个子流域稻田的空间格局变化削弱了稻田对氮磷流失的拦截净化能力。在小雨、中雨期和基流期，TN流失浓度显著增加。TP流失浓度在中雨转大雨过程中波动。因此，增加流域稻田面积并合理优化其空间格局是控制三峡库区农业面源污染的有效措施。
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