Soil urease activity affected by copper

Copper is a double element in the soil.In order to investigate the copper eco-toxicity by means of soil enzyme,the relationship between soil urease and copper is systematically studied by using simulative method.The results showed that soil urease activity was increased with the improvement of soil fertility.But the urease activity was remarkably reduced by the introduction of copper into soil,and the relationship between them was up to the significant negative correlation level so that soil urease activity could be used as a testing index of soil polluted by copper.Calculated copper ecological dose ED10 and ED50 values,which could be used as different polluted levels,were 94.00-151.75 and 470.40-759.28 mg/kg in soils tested.Urea concentration showed little effect on ecological dose.The kinetic parameters such as Vmax,Vmax/Km and k were reduced with the increase of copper concentration,and their relationship was up to the significant negative correlation levels,except the increased Km value.It was proved that the copper reaction mechanism was a mixed inhibition,including both competitive and non-competitive effect,while the non-competitive mechanism was more important.Our results demonstrated that soil urease could be used as an indicator for soil copper pollution.