不同源类型农业非点源负荷特征研究——以新田小流域为例

Load characteristic of agricultural non-point source pollution based on various source-types: a case study on Xintian watershed

以珠江三角洲北部新田小流域为研究对象,采用源类型法,在流域范围内建立林地、果园、旱地和水田四个全封闭的农业用地单元,并对四个单元出口处的径流量进行同步采样,分析COD、BOD、氨氮、总氮和总磷等污染物的负荷特征。结果表明:(1)流域地表水存在着明显非点源污染现象,不同源类型,地表径流的污染程度不同。(2)不同源类型农业非点源污染负荷强度不同,其中水田、旱地单位面积非点源负荷强度较大,果园、林地各项污染物的负荷强度相对最小。受地表扰动、施肥等人类活动影响,流域内水田、旱地是农业非点源污染发生的关键源区。(3)流域范围内,不同源类型农业非点源负荷总量不同,其中,果园各项污染物非点源负荷总量最大,其次是林地,水田、旱地非点源负荷输出总量较小,流域范围内,源面积成为影响非点源负荷总量的主要因素。(4)相应的非点源污染治理不仅是关键源区,同时应关注大面积流失区。

Based on source-type method, the four types, include forest, orchard, dry land, and paddy field were setup in Xintian watershed, a representational agricultural catchment in the Pearl River Delta, and load characteristic of agricultural non-point source pollution of CODcr, BOD5, NH3-N, TN, and TP, were analyzed on each type. The result showed that （1） the surface water was obviously polluted by agricultural non-point source in watershed, the degree of pollution varied with source-types, （2） the load of per area differed from source-types, the source-types of paddy field and dry land were main critical source areas （CSA） of agriculture non-point source pollution, which because of the higher load than the source-types of orchard land and forest land, （3） the total load was decided by the source-type areas in watershed, the total load output of orchard land was more than the other types because of the larger areas, and （4） CSA and larger areas source-types were same important to control agricultural non-point sources pollution.