农田氮素非点源污染模型及年负荷估算研究

研究了农田中氮素随径流动力输出的过程，并依据径流特征和农田氮肥施用情况，将全年区分为水田施肥期、水田生长期和非水田期.按试验时的天气条件，分别采用人工模拟降雨或农田实测降雨的资料，分析农田非点源污染回归模型.水田施肥期采用人工模拟集中降雨情形，降雨强度为2 mm&;#8226;min^-1，模型氮素浓度范围为28~45 mg&;#8226;L^-1；水田生长期和非水田期采用天然降雨，降雨强度为0.037 6~0.075 1 mm&;#8226;min^-1，模型氮素浓度为0.2~4.0 mg&;#8226;L^-1.在分析长系列降雨资料的基础上，综合运用修正SCS（Soil Conservation Service）法、单位线法和相关分析法，估算得到农田径流过程排放的氮素量，再加上地下水渗漏流失的氮素量，取得上海地区一般降水年份农田的氮素非点源污染年负荷量为26.5 kg&;#8226;ha^-1.

Research on Nitrogen Nonpoint Source Pollution Model in Farmland of Shanghai Suburbs(Chinese)

According to the characters of runoff and fertilization, the runoff process in the farmland was divided into paddy field fertilization period, paddy field growth period and dry land period. Based on the fieldwork in Shanghai area, the regress model of nonpoint source pollution in these three types of farming period were developed. There is difference between the simulated and actual precipitations situations. Nitrogen concentration during the simulated precipitations varied between 28 mg•L^-1 and 45 mg•L^-1, with the precipitation density at 2 mm•min^-1, and the nitrogen concentration during the actual precipitation varied between 0.2 mg•L^-1 and 4.0 mg•L^-1, with the precipitation density varing between 0.037 6 mm•min^-1 and 0.075 1 mm•min^-1. Based on the long-term precipitation data and nitrogen loss in the groundwater, by the modified SCS method the annual nitrogen load in the farmland was calculated, and the value is 26.5 kg•ha^-1.