Chen Shi-Qi, Long Yi, Yan Dong-Chun, Gao Ming, Li Jia-Chen, Xu Guo-Xin, Huang Rong
College of Resource and Environment, Southwest University, Chongqing 400715, China.
Institute of Mountain Hazards and Environment, Chinese Academy of Sciences and Ministry of Water Resources, Chengdu 610041, China.
Huan Jing Ke Xue. 2020 Mar 8;41(3):1276-1285. doi: 10.13227/j.hjkx.201909082.
As the source of non-point pollution in the Three Gorges Reservoir Area, small watershed is a key control object in alleviating deterioration of water quality. In the Three Gorges Reservoir Area, the Shipanqiu small watershed with various land-use types was selected as the research object, and the water quantity and quality of the outlet section of the watershed were continuously monitored. We carried out analysis of the small watershed runoff loss and nitrogen and phosphorus pollutants with concentration, analyzed the morphology change characteristics of runoff erosion, calculated the small watershed of pollutant emission flux, and analyzed the nitrogen and phosphorus nutrient loss and main human and natural factors, especially in the Three Gorges Reservoir Area of agriculture where nonpoint source pollution research has important practical significance. The results showed that the rainfall in the watershed varied significantly with the seasons, and the rainfall was mainly distributed from April to June, which was the main output period of nitrogen and phosphorus loss in the small watershed, accounting for 58.94% and 67.60% of the total nitrogen and phosphorus load, respectively, in the whole year. The total annual runoff in the Shipanqiu small watershed was 8.02×10 m, and the annual total nitrogen loss flux was 5.04 kg·hm, of which nitrate nitrogen (2.54 kg·hm) was the main part. The total phosphorus output was 0.534 kg·hm, and the soluble total phosphorus (0.422kg·hm) accounted for 79.00% of the total phosphorus flux. The loss flux of total nitrogen was 9.51 times that of total phosphorus, and the non-point source pollution risk of nitrogen was much greater than that of phosphorus. Therefore, for the Shipanqiu small watershed, it is especially important to prevent nitrogen loss in paddy fields when fertilization and rainfall coincide.
作为三峡库区非点源污染的源头，小流域是缓解水质恶化的关键控制对象。在三峡库区，选取了土地利用类型多样的石板丘小流域作为研究对象，对该流域出口断面的水量和水质进行持续监测。开展了小流域径流损失及氮磷污染物浓度分析，剖析了径流侵蚀的形态变化特征，计算了小流域污染物排放通量，分析了氮磷养分流失及主要的人为和自然因素，特别是在三峡库区农业面源污染研究具有重要现实意义。结果表明，该流域降雨随季节变化显著，降雨主要集中在4—6月，这是小流域氮磷流失的主要输出期，分别占全年总氮、总磷负荷的58.94%和67.60%。石板丘小流域年径流总量为8.02×10立方米，年总氮流失通量为5.04千克·公顷，其中硝态氮（2.54千克·公顷）为主要部分。总磷输出量为0.534千克·公顷，可溶性总磷（0.422千克·公顷）占总磷通量的79.00%。总氮流失通量是总磷的9.51倍，氮的面源污染风险远大于磷。因此，对于石板丘小流域，施肥与降雨重合时防止稻田氮素流失尤为重要。
