N-丁基硫代磷酰三胺对淹水土壤脲酶动力学特征的影响

摘要

研究了淹水状态下脲酶抑制剂N-丁基硫代磷酰三胺(NBPT)对东北4种典型土壤(黑土、白浆土、棕壤、褐土)脲酶动力学参数的影响.结果表明,NBPT对土壤脲酶动力学参数的作用程度受土壤类型、培养时间及其交互作用的显著影响.与对照相比,NBPT使土壤脲酶米氏常数(Km)增加,最大反应速率(Vmax)和Vmax/ Km降低,表明NBPT对土壤脲酶的作用机理属于典型的混合型抑制.随培养时间延长,土壤脲酶Km降低,Vmax和Vmax/ Km升高,表明NBPT对脲酶的抑制效力逐渐减弱.黑土、白浆土脲酶Km值小于棕壤和褐土,而Vmax则大于棕壤和褐土,表明土壤肥力水平能够影响土壤脲酶的动力学参数.相关分析表明,土壤脲酶Km与粘粒和粉粒含量呈显著正相关关系,与pH值呈显著负相关关系；而Vmax和Vmax/ Km的相关性则正好与此相反.%The effects of N- (n-Butyl) Uuophosphonc tnamide ( NBPT) on kinetic parameters of four typical soil urease in Northeast China (black soil, albic soil, brown soil, cinnamon soil) in a waterlogged system were studied. The results showed that effects of NBPT on kinetic parameters of soil urease were significantly influenced by soil type, incubation time and their interactions. Compared with control, NBPT made Km increase but Vmax and Vmax/Km decrease, indicating that the action mechanism of NBPT on soil urease was of competitive inhibition. With incubation time increasing, Km of soil urease decreased, but Vmax and Vmax/Km increased, providing evidence that the effectiveness of NBPT on soil urease gradually weakened. The urease in black soil and albic soil had smaller values of Km than that in brown soil and cinnamon soil, but larger values of Vmax, indicating that soil fertility could influence the kinetic parameters of soil urease. Statistical analysis indicated that, Am of soil urease had significantly positive correlations with clay content and silt content, and significantly negative correlations with pH; But the correlations of Vmax and Vmax/Km were in adverse.