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

【Objective】 Influence of Cr3+ on soil enzymes was studied to provide a foundation for enzyme assessment index in soils polluted by heavy metals.【Method】 Red soil,Cinnamonl and sandy soil,main soil types in China,were sampled.By simulative method,soil urease,phosohatase,arylsulphatase,catalase,dehydrogenase and total enzyme activities were studied under different Cr3+ concentrations 0,50,100,300,500,1 000,1 500,3 000 mg/kg.【Result】 Soil urease,phosohatase,arylsulphatase,catalase,dehydrogenases enzymes significant or remarkably significant negative correlation with Cr3+ concentrations was obtained.And the reaction mechanism was complete inhibition(including competitive inhibition and noncompetitive inhibition).The critical Cr3+ concentration was 25 mg/kg when the soils were slightly polluted(ED10),arylsufatase and catalase were more sensitive to Cr3+ in acid soils,however,in alkalinen soil phosohatase and dehydrogenases were more sensitive.【Conclusion】 Soil urease,phosohatase,arylsulphatase,catalase,dehydrogenases enzymes and total enzyme activity could be index to monitor soils polluted by Cr3+,soil enzyme impact was up to soil physic-chemical properties,such as pH and organic matter content.