开封城市土壤磷素组成特征及流失风险

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

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 1427 mg·kg^-1, the proportions of inorganic P in total P ranged from 65% to 99%, and Olsen-P and CaCl₂-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.