Effects of mercury and chlorimuron-ethyl on soil urease activity and its kinetic characteristics

With incubation test, this paper studied the effects of mercury (Hg), chlorimuron-ethyl, and their combination on the urease activity and its kinetic characteristics in meadow brown soil and black soil. The results showed that Hg had negative effects on the activity, Km, Vmax, and Vmax/Km of soil urease, with the affecting range of 39%-98%, 46%-74%, 90%-98%, and 20%-68%, respectively. The relationship between soil urease activity and HgCl2 concentration could be described with logarithmic equation, and the Km, Vmax, and Vmax/Km of soil urease were linearly negatively correlated with HgCl2 concentration. Chlorimuron-ethyl could activate soil urease activity, possibly because of the enhancement of initial velocity of urease reaction. The combination of Hg and chlorimuron-ethyl also had negative effects on the urease activity and its kinetic characteristics, with the affecting range similar to that of Hg, but poorer correlations were observed with the pollutants concentration. The addition of chlorimuron-ethyl made the interaction between Hg and soil urease more complicated.