北运河下游不同土地利用非点源污染负荷估算

选取我国北方地区以圩区为主要形式的北运河下游农业灌溉区——天津武清区和北辰区作为研究对象,针对不同土地利用类型进行降雨径流污染物浓度监测,采用美国土壤通用流失方程（USLE）、降雨径流模型（SCS-CN）、综合径流系数法等,结合GIS技术,分别估算了透水地面和不透水地面的氮磷负荷量。结果表明,非点源污染总氮、总磷的年负荷量分别为2865.04t.a-1和101.22t.a-1,不透水地面所产生的TN、TP负荷量分别占研究区污染负荷总量的81%和67%,透水地面所产生的TN、TP负荷量分别占研究区污染负荷总量的19%和33%（且污染物形态以溶解态为主,分别达到了81%和74%）。对于不同土地利用类型,总氮流失主要来源于村庄（贡献率为49%）、城镇（贡献率为17%）和耕地（贡献率为16%）,而总磷主要来源于村庄（贡献率为31%）、耕地（贡献率为23%）和城镇（贡献率为19%）。从产污强度来看,城镇用地是最高的,是其他土地利用类型的10倍以上。

Non-point Source Pollution Loads from the Different Land Use Types in the Downstream Areas of the Beiyunhe River Basin, China

Wuqing and Beichen district, which are the agricultural irrigation plain in the downstream watershed of Beiyunhe River, were se- lected as research areas. The land use types were divided into pervious（ such as farmland ） type and impervious （such as urban areas and vil- lages ） type. The concentrations of pollutants in runoff from different land uses were monitored. Based on the platform of GIS, the estimation of the loads of non-point source pollution（NPS） were obtained by using universal soil loss equation of the United States（USLE ）, curve number method（SCS-CN） and an integrated runoff coefficient method. The resuhs indicated that the NPS loads of TN and TP of the watershed were 2865.04 t. a^-1 and 101.22 t.a^-1, respectively. In the impervious area, the loads of TN and TP accounted for 81% and 67% of the total. In the pervious area, the pollutant load of TN and TP accounted for 19% and 33% of the total（The dissolve N and dissolve P were the dominant loss forms, accounting for 81% and 74% of total loads from pervious landuse types, respectively）. In terms of different land use type, for TN, the main pollution sources were village, urban areas and croplands, accounting for 49%, 17% and 16% of total load, respectively. For TP, the main pollution sources were village, croplands and urban areas, accounting for 31%, 23% and 19% of total load, respectively. The pollution intensity of urban areas was 10 times higher than that of other land use types.