太湖流域跨界区农业面源污染特征

摘要

To illustrate the transboundary non-point source agricultural pollution in the Taihu valley, first of all, COD, TN and TP loads in the pollution were figured out with an export coefficient model by calculating the loads separately in the three major contributors of the pollution, i.e. domestic sewage and household refuse from rural population, agricultural run-off and waste from livestock keeping, and temporal and spatial variations of the loads were characterized;Then, discharge intensities of the loads in various regions of the transboundary area were evaluated with the extremum method and the mean variance weighting method. Results show that during the years from 2010 to 2013, the COD, TN and TP loads on the whole were on a declining trend;during the four years, high COD load appeared in Huzhou and Jiaxing and high TN and TP loads in Suzhou, Huzhou and Jiaxing;livestock keeping was the main contributor of the three loads, explaining 80% of the total load. Evaluation of discharge intensity of the loads indicates that the comprehensive index of the non-point source agricultural pollution per unit GDP was 0. 2176, 0. 2402, 0. 2364 and 0. 2222, respectively, for the four years, which did not show any rule of variation, while the comprehensive index of the non-point source agricultural pollution per unit ar-ea was 0. 4078, 0. 2899, 0. 2892 and 0. 2816, which obviously followed a declined trend.%采用输出系数法,从农村生活污水、农田径流和畜禽养殖3个来源估算太湖流域跨界区农业面源COD、TN和TP污染负荷,并分析其时空变化特征;采用极值标准化法和均方差赋权法,进一步对区域内各地区污染负荷的入水强度进行评价.结果表明,太湖流域跨界区2010—2013年COD、TN和TP入水负荷总体呈下降趋势,4 a间高COD负荷区分布在湖州市和嘉兴市,高TN和TP负荷区分布在苏州市、湖州市和嘉兴市,畜禽养殖是3种污染负荷的主要来源,均占3种污染物总负荷量的80%以上.各地区污染负荷的入水强度评价结果显示,2010—2013年跨界区农业面源污染负荷单位GDP综合评价值分别为0.2176、0.2402、0.2364和0.2222,无明显变化规律;流域农业面源污染负荷单位面积综合评价值分别为0.4078、0.2899、0.2892和0.2816,呈下降趋势.