Effect of heavy metals on soil denitrification and CO2 production after short term incubation.

The toxicity of three heavy metals, Cd, Zn and Cu, has been tested in a Mediterranean soil. The soil was incubated (108h) with mixed solutions of those metals before evaluating denitrification and CO2 production, both by gas chromatography. These activities were used as biological indicators of heavy metal toxicity, and compared to non-treated control soil samples. Statistical analyses showed no significant differences in CO2 production between treated and non-treated control soils. The lowest levels of respiration were observed in soils treated with the largest amounts of Zn and Cd. Denitrification increased significantly in soils treated with solutions containing 100 micrograms/ml of Cu and 1000 micrograms/ml of Cd or Zn.