• 关键词：太湖流域  非点源污染  土壤磷素  吸持指数  风险分析

• 基金项目：中国科学院“九五”重大项目(KZ951A1301);中国科学院特别支持项目(KZ95T0401)

• 高超
• 中国科学院南京土壤研究所,南京 210008

• 张桃林
• 中国科学院南京土壤研究所,南京 210008

• 吴蔚东
• 中国科学院南京土壤研究所,南京 210008

• 摘要：通过对比土壤的固磷能力和磷素水平可以评估不同类型土壤中的磷向水体释放的风险.研究表明,磷吸持指数(SI)可以作为土壤最大吸磷量的替代指标来表征土壤的固磷能力.在太湖地区,影响水土界面磷素迁移能力的主要因素是土壤有效磷水平和土壤固磷能力.SI值30左右为一临界值,SI大于此值的土壤对于施磷具有较大的缓冲能力,而SI低于此值的土壤对施磷非常敏感,磷流失风险将随施磷量的增加而呈直线上升趋势.

• Abstract：The risks of agricultural soil phosphorus loss to surface waters in Taihu lake watershed were evaluated by comparing the P sorption capacity with available P level in different kinds of soils. The results showed that phosphorus sorption index (SI) is a simple yet adequate paramenter to estimate P sorption capacity,which can be used to characterize the potential of a given soil for P release to runoff as a result of P amendments. In the studied area the SI value 30 is a critical point.Above the value soils have a considerable buffering capacity to the addition of P, but soils with SI value less than 30 are very sensitive to P amendments. So it is pointed that great risk of P loss may happen if excessive amount of P fertilizer is applied to these soils.

• Key words：Tahu lake watershed  nonpoint source pollution  soil phosphorus  sorption index  risk evaluation

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