基于改进输出系数模型的农业源污染物负荷核算

选择滇池流域作为案例, 考虑区域自然地理、水文气象以及人类活动影响等因素的差异性, 利用1 km×1 km栅格数据, 开展农业源污染物TN和TP入水体系数的精细化模拟测算, 得出降雨驱动因子、地形驱动因子、地表径流因子、地下蓄渗/地下水径流因子和截留因子, 计算得到2016年滇池流域农业源TN和TP的平均综合入水体系数分别为0.447和0.342, 进而估算得到滇池流域2016年全年农业源污染物TN和TP实际入水体负荷量分别为577.39和167.62 t。研究结果表明, 滇池流域农业源污染物排放量和入水体负荷量存在显著的空间分布差异, 81.0%的氮排放量和74.2%的磷排放量集中分布在草海陆域和外海北岸, 排放量最大的是位于外海的盘龙江上游, 分别占氮、磷总排放量的21.9%和20.2%。此外, 农业源污染物TN和TP排放量中, 来自畜禽养殖的污染占比超过90%, 应作为农业源污染控制的重点关注目标。

Estimation of Agricultural Non-point Source Pollution Loads Based on Improved Export Coefficient Model

The Dianchi watershed Basin was selected as a typical watershed. Considering the differences of regional natural geography, hydrometeorology and human activities, using 1 km×1 km grid data, the detailed simulation calculation of the pollutants entering the water source of agricultural sources is carried out. The rainfall driving factors, terrain driving factors, surface runoff factor, underground storage/groundwater runoff factor and interception factor are obtained. The average comprehensive water inflow coefficients of TN and TP from agricultural sources in Dianchi Basin in 2016 are 0.447 and 0.342 respectively, and the actual water inflow loads of TN and TP from agricultural sources in 2016 are 577.39 t and 167.62 t respectively. The results show that the discharge of agricultural source pollutants and the load of influent water have significant spatial variation in Dianchi Lake Basin. 81.0% of nitrogen and 74.2% of phosphorus were concentrated in Caohai land area and the north coast of the open sea. The largest emission was in the upper reaches of Panlong River, with nitrogen and phosphorus accounting for 21.9% and 20.2% respectively. It is also found that livestock and poultry breeding account for more than 90% of the total TN and TP emissions of from agricultural sources, which should be the focus of agricultural source pollution control.