Effects of Cr~(3+) on soil enzyme activity

【Objective】The effect of Cr3+on activities of soil urease and dehydrogenase was studied to screen the enzymology indicators for soil Cr3+pollution and the main factors influencing the relationship between enzymes and Cr3+.【Method】Using laboratory simulation method,we studied the effect of Cr3+on activities of soil urease and dehydrogenase in 18typical soil samples collected nationwide.【Result】Cr3+ generally inhibited the activities of urease and dehydrogenase with significant or extremely significant relations.The reaction was complete inhibition(including competitive inhibition and noncompetitive inhibition).The critical pollution concentrations of urease and dehydrogenase were 16.38and 4.32mg/kg respectively,which were lower than the second level of national standards.【Conclusion】To a certain extent, activities of soil urease and dehydrogenase can be used to characterize soil Cr3+pollution.The soil pH and organic matter were the domain factors deciding the effects of Cr3+on activities of soil urease and dehydrogenase,respectively.