Effect of Sublethal Concentration of Heavy Metal Contamination on Soil Physicochemical Properties, Catalase and Dehydrogenase Activities

The effect of sublethal contaminations (100 mg/dm3) of heavy metals such as mercury (Hg), lead (Pb) and cadmium (Cd) on soil enzyme and physicochemical properties was investigated after one hundred and twenty days. Soil sample without heavy metal contamination served as the control. Results indicate that Hg, Pb and Cd at 100 mg/dm3 concentration caused a significant (P<0.05) change in the soil pH and electrical conductivity relative to the control. There was no significant (P>0.05) difference in these

soil physicochemical properties: moisture, phosphate, sulphate, chloride, calcium carbonate, total nitrogen and organic carbon when compared to the control. There were significant (P<0.05) decrease in soil dehydrogenase and catalase activities in all the metal-contaminated soil samples when compared to the control, indicating that these heavy metals increased soil acidity and electrical conductivity at this concentration and period of exposure.