珠江三角洲典型流域颗粒态氮磷负荷估算研究

Estimation of the Loads of Particulate Nitrogen and Phosphorus in Typical Drainage Area of Pearl River Delta

珠江三角洲地区菜果花农业发达,农业化学物质投入量大,区域N、P等养分流失迅速,水环境问题尤为突出。选取广州流溪河为研究对象,应用GIS和USLE模型结合土壤污染实测数据,采用源类型法估算流溪河流域的颗粒态N、P污染负荷。结果表明:(1)流溪河流域的颗粒态N、P总流失量分别为582.49t·a-1和424.74t·a-1,其中N流失量中水田贡献最大占40.02%,其次为林地占26.31%;P流失量中旱地贡献最大占28.75%,其次为水田占26.94%。(2)流域不同源类型单位面积颗粒态N、P流失量差异显著,旱地的N、P单位面积流失量均为最高,分别是7.72kg·hm-2和9.50kg·hm-2;其次为果园,N、P分别是7.20kg·hm-2和6.56kg·hm-2。(3)流域颗粒态N、P流失总量及其单位负荷受农业施肥影响,农业生产过程产生的过量N、P物质是流溪河流域重要的N、P负荷污染来源。

The output of nitrogen and phosphorus from agricultural activities is the main source for water eutrophication. The fully developed agriculture in vegetables, fruits and flowers in Pearl River Delta gives rise to excessive use of chemical matter such as fertilizer and pesticide and thus bring about the serious water pollution because of the loss of nitrogen（N ） and phosphorus （P） from the farmland in the region. Based on Geographic Information System（ GIS ） and soil pollution data, Universal Soil Loss Equation（USLE ） and source type method are used to estimate the loads of particulate N and P from the soil of different land use types in the drainage area of Liuxi River in Guangzhou, China. So the key regions those the NPS pollution occurred can be confirmed and the technical support for the pollution control target and the capital flow concentration can be provided by the results. The study shows that：（ 1 ）The total loss of particulate N and P in the drainage area is 582.49 t·a^-1 and 424.74 t·a^-1 respectively. Among them the loss of particulate N from paddy soil occupies 40.02% and that of forest 6.31%, while the loss of particulate P from the soil of dry-land accounts for 28.75% and that of paddy soil 26.31%. （2）There are significantly different losses of particulate N and P per unit area from the soils of different source land use types in the drainage area. The losses of particulate N and P per unit area are both the highest from the soil of dry-land, which is 7.72 kg ·hm^-2 and 9.50 kg ·hm^-2 respectively, followed by those of orchard, which is 7.20 kg·hm^-2 and 6.56 kg·hm^-2 respectively. The causes are excessive use of chemical matter, unreasonable cultivation pattern, and the soil erosion of different land use. （ 3 ）The excessive N and P come from the loss of particulate N and P from the fertilization in agricultural production, and they are the main source of the pollutants in Liuxi River water.