Eco-toxicology effects of Cu-Cr co-contamination on soil enzyme with or without plants.

Pot experiments and laboratory analysis were carried out to study Cu,Cr single and combined pollution influence on soil enzyme activities.The aim was to provide theoretical basis for biological enzyme evaluation of heavy metal cation-anion co-contamination in soil.The results showed that the same pollution level Cu and Cr singly or combined had inhibited effects on activity of urease,alkaline phosphatase,catalase and nitrate reductase.while in the 5 mg.kg-1 Cr treatment,the activity of catalase was promoted.Catalase was the least sensitive en-zyme to Cu-Cr cocontamination,while soil nitrate reductase was the most sensitive one to Cu-Cr cocontamination.Inhibition rates of urease and alkaline phosphatase activities in the planted treatment were larger than the non-crop control treatment.However,inhibition rate of cata-lase and nitrate reductase activities in the planted treatment were smaller than thoes in the non-crop control treatment.There was extremely significant difference in the planted treatment of all enzymes,compared with the non-plant treatment.Whether having plants or not,Cu and Cr combined pollution showed a certain synergyon on the inhibition rate of soil urease and alkaline phosphatase activities,a certain antago-nism on the inhibition of soil catalase activity,and a certain synergyon on nitrate reductase activity in non-crop control treatment,futhermore there was a certain antagonism on nitrate reductase activity in the planted treatment.Urease and alkaline phosphatase activities were suggest-ed to characterize the degree of Cu and Cr combined pollution in soil.