官厅水库周边不同土地利用方式下氮、磷非点源污染模拟研究

Simulation study of non-point source pollution under different landuse in Guanting Reservoir watershed

利用小型人工降雨模拟器 ,选择官厅水库周边 4种典型土地利用类型 ,通过进行天然大暴雨实验 ,研究了氮、磷随暴雨径流及径流沉积物的迁移过程 ,同时估算了总氮、总磷在不同土地利用方式下的流失速率 .研究结果表明 ,在相同降雨条件下 ,4种土地利用类型的产流量和沉积物产生量大小顺序均为 :不施肥菜地 >葡萄果园 >施肥玉米地 >海棠果园 ,产流量和沉积物流失量成显著正相关 .氮、磷流失速率和流失量随土地利用类型的不同表现出明显差异 ,地表径流水相TN、TP的流失大小顺序为葡萄果园 >施肥玉米地 >海棠果园 >不施肥菜地 ,其中大部分是以悬浮颗粒态形式流失 .单位面积表层 10cm土壤氮、磷流失量分别高达 17.5 3～ 41 14g·m- 2 和 1 99～ 14 2 5g·m- 2 ,其中随径流沉积物相迁移的氮、磷占绝大部分 .地表径流水相氮、磷的流失速率分别在 2 5 9～ 4 47mg·m- 2 ·min- 1 和 0 43～ 0 63mg·m- 2 ·min- 1 之间 ,而径流沉积物相氮、磷流失速率则分别高达 3 86 42～ 13 61 76mg·m- 2 ·min- 1 和 2 10 5 6～ 5 3 0 19mg·m- 2 ·min- 1 .

Four typical land covers in Guanting Reservoir watershed were studied on nutrients loss in artificial rainstorm runoff simulator. Transportation and flux of various species of nitrogen and phosphorous in runoff and sediments were investigated. The results showed that the amounts of runoff and sediment followed the order that Farmland without fertilizer > Grape garden > Maize farmland with fertilizer > Chinese flowering crabapple orchard under the same rainfall condition. The amount of runoff had directly positive correlated with that of sediment. The amount and rate of nutrient losses were different among four types of landuse. The loss of total nitrogen and total phosphorous in runoff followed the order that Grape garden > Maize farmland with fertilizer > Chinese flowering crabapple orchard > Farmland without fertilizer, where most of TN and TP were lost through suspended particles. And total amounts of nitrogen and phosphorous loss from top 10cm layer of 4 kinds of soils were estimated as high as 17.53～41.14g·m^(-2) and 1.99～14.25g·m^(-2), in which the nutrients loss through sediment of runoff accounted for more than 99%. The rate of total nitrogen and phosphorous losses were ranged in 2.59～4.47mg·m^(-2)·min^(-1) and 0.43～0.63mg·m^(-2)·min^(-1) in liquid of runoff, which was much lower than that of 386.42～1361.76mg·m^(-2)·min^(-1) and 210.56～530.19mg·m^(-2)·min^(-1) in sediment of runoff.