开封城市土壤磷素组成特征及流失风险

Characterization of Phosphorus in Urban Surface Soils in Kaifeng City and Its Risk of Loss

为深入了解城市土壤磷素组成特征及其对受纳水体的影响,以开封城市表层土壤为研究对象,分析开封城市不同功能区土壤磷素的组成特征,并采用"突变点"法计算土壤磷素流失临界值,探讨开封城市不同功能区表层土壤磷素流失风险.结果表明,开封城市土壤总磷为400~1 427 mg·kg^(-1),其中无机磷占65%~99%;速效磷(Olsen-P)和易解吸磷分别为3.41~115.03 mg·kg^(-1)和0.01~9.40 mg·kg^(-1),与土壤磷素背景值相比,城市土壤磷素呈现明显集聚.开封城市土壤总磷和速效磷均呈现出东高西低,中心老城区高于新城区的空间分布格局;在不同功能区分布上,居民区土壤各形态磷素含量均最高.开封城市土壤磷素流失临界值对应的Olsen-P为22.18 mg·kg^(-1),超过临界值的土样占总土样数的33.64%,磷素流失风险最高的区域亦分布在中心老城区.

Characterization of phosphorus（ P） and its risk of loss in urban soils in Kaifeng City,Henan Province were studied through field sampling and laboratory experiments. The spatial distribution of P and the map of risk of loss were obtained using geostatistical and spatial analysis techniques. The P content in urban soils ranged from 400 to 1 427 mg·kg^（-1）,the proportions of inorganic P in total P ranged from 65% to 99%,and Olsen-P and CaCl_2-P in soils were 3. 41-115. 03 mg·kg^（-1） and 0. 01-9. 40 mg·kg^（-1）,respectively. The composition of P was consistent in different urban areas and P concentrations were higher in residential areas. Spatial variations in P concentrations in soils were significant; the concentrations of P in eastern Kaifeng City were higher than those in western Kaifeng and the highest concentrations were detected in central Kaifeng. Olsen-P can be used as an indicator of the leaching risk of soil P. The critical value of leaching P from the soil was 22. 18 mg·kg^（-1） and the concentration of Olsen-P in 33. 64% of urban soil samples exceeded the critical value. The highest risk of P loss existed in central Kaifeng City.