基于柴河流域汇水区内不同景观单元土壤与径流中氮、磷养分含量,分析了土壤与径流中污染物的生态化学计量特征,并综合评价了面源污染物的“源—流”过程,进而确定汇水区内面源污染防控的重点区域。结果 表明:(1)汇水区内的坝平地、大棚种植区和柴河河道的土壤或底泥具有较高的氮磷比,其径流中溶解态氮磷比也较高,而磷矿区和富磷区林地土壤及径流中溶解态氮磷比较低;(2)土壤氮、磷养分与径流中氮、磷污染物之间未发现显著相关性(p>0.05);(3)与其他景观类型相比,柴河底泥与大棚种植区的污染物“源”强较高,而大棚种植区和磷矿区污染物的“流”失风险较高,因此,大棚种植区由于其高“源”强和高“流”失性是该汇水区面源污染重点防控区域;(4)单个景观类型下,通过对比“源”“流”过程在总流失风险中的比例确定磷矿区的流失、富磷区林地和河道底泥的污染物“源”是各自景观类型下面源污染防控的重点环节; 而农业种植区(坡耕地、坝平地和大棚区)需同时在减“源”和控“流”上进行综合防控。
Based on the nitrogen(N)and phosphorus(P)concentrations in soil and surface runoff from different landscape units in the Chaihe catchment, the eco-stoichiometric characteristics of pollutants were analyzed. The key control area of non-point source pollution was then identified in the catchment according to the comprehensive evaluation values of the source-flow processes using ecological stoichiometry. The results showed that:(1)soils in the flat lands and the greenhouse area and sediment in the Chaihe river had higher values of N:P ratios; the values of the dissolved N and P ratio in the runoff were also higher; in contrast, the values of N:P ratio in soil and runoff in P-mining area and forests in P-enriched area were relatively low;(2)there were no significant correlations between soil nutrients and pollutants in runoff;(3)compared to other landscape units, the higher values of pollutant source were found in the sediment of the Chaihe river and the soil in the greenhouse area, and the higher risk of pollutant flow in runoff was found in the greenhouse areas and the P-mining area; consequently, the greenhouse area was considered as the key area of pollutant control in the catchment area due to its high-risk values of pollutant source and flow;(4)according to the proportion of the pollutant source and flow processes, the pollutant flow process in the P-mining area and pollutant source in forests of P-enriched area and river sediment were considered as the key aspects of the non-point source pollution control in each landscape; non-point source pollution in farmlands(slope farmland, flatland, and greenhouse area)should be simultaneously controlled in processes of the soil pollutant source and pollutant flow in runoff.
