[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, the proportions of inorganic P in total P ranged from 65% to 99%, and Olsen-P and CaCl-P in soils were 3.41-115.03 mg·kg and 0.01-9.40 mg·kg, 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 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.