中文摘要：

磷是导致湖泊水体富营养化的主要污染物质。本文对滇池宝象河流域稀疏林地、坡耕地、平地耕地及大棚土壤的0～5 cm、5～10 cm、10～20 cm层土壤全磷、有效磷、磷固定量及磷吸持指数（PSI）等指标进行了测定或计算，并就磷的累积与分布特征、吸附特征等进行了评价。结果表明：流域表层土壤的全磷、Olsen-P和水溶性磷均有明显的累积，尤以大棚土壤磷的累积效应最为明显（平均值分别为1.67 g kg-1、75.9 mg kg^-1和27.7 mg kg^-1），且Olsen-P和水溶性磷的含量在耕层各层次上表现为从上往下依次降低的趋势。吸附特征方面，表层土壤的磷固定量在68.4～351.2 mg kg^-1之间，不同土地利用类型不同土壤层次间的土壤磷固定量无显著差异；而土壤的PSI值以上游稀疏林地和坡耕地土壤中的显著较高，根据PSI值低于30的比例，推测出中上游平地耕地和下游大棚区土壤磷素存在着较大的潜在流失风险。

英文摘要：

Phosphorus （P） is the principal pollutant contributing to eutrophication of water bodies. Contents of total P,available P and fixed P in soils of different layers （0～5 cm,5～10 cm and 10～20 cm） under different land use （sparse forest soil,sloping farmland,flat farmland and greenhouse soil） in the Baoxiang River watershed in the Dianchi Lake region were determined,and P Sorption Index （PSI） were calculated. And accumulation,distribution and sorption characteristics of P in the soils were also evaluated. Results show that total P,OlsenP and water soluble P accumulated significantly in the topsoil,especially of greenhouse soil,averaging 1.67 g kg-1,75.9 mg kg-1 and 27.7 mg kg-1,respectively; and the contents of Olsen-P and water soluble P displayed a decreasing trend from the surface layer down with the depth. In respect to sorption characteristics,the contents of soil fixed P in the topsoil ranged from 68.4 mg kg-1 to 351.2 mg kg-1,showing little difference between soil layers under different land use,while PSI values of the soils were obviously higher in sparse forest soil and sloping farmland in the upper streams. The PSI values of the soils of the flat farmland in the middle-upper streams and the greenhouse soli in the downstream were 〈 30,suggesting that the potential risk of soil P loss is high.