Variable effects of heavy metal contamination on soil enzyme activities due to the metal type, the contamination
mode and the contact time have been reported previously. For example, Dar (1996) found that Cd as sole contaminant
decreased the soil enzyme activities when its concentration was as high as 50 mg kgK1 .
Moreno et al. (1999) reported that high Cd concentrations (O800 mg Cd kgK1) affected dehydrogenase activity, but not b-glucosidase urease and phosphomonoesterase activities