Kinetics characters of soil urease, acid phosphotase and dehydrogenase activities in soil contaminated with mixed heavy metals

The kinetics characters of enzymatic activities in soil contaminated with heavy metals in the lead-zinc tailing mine were studied. Soil enzyme activities decreased markedly with increasing degree of soil pollution caused by heavy metals in the mine area. The average Vmax values of soil urease, phosphotase and dehydrogenase in the mine area were 60%, 77% and 38% of those of non-mine area, and that the average Km values of soil urease, phosphotase were 2.73 and 2.25 times than those of non-mine area, respectively. The stepwise regression and path analysis further showed that kinetics parameters (Vmax and Km) of the reaction promoted by soil urease, phosphotase and dehydrogenase were significantly correlated with the concentrations of heavy metals such as Pb, Zn, Cu and Cd in soil of the mine area. However, the degree of the influence of each heavy metal on the activity of different enzymes was greatly different, and moreover, there was an interacting effect of four heavy metals.