Potential nitrification, nitrate reductase, and β-galactosidase activities as indicators of restoration of ecological functions in a Zn-contaminated soil

The present study was conducted to assess the possible restoration of different ecological functions in a Zncontaminated soil. Experiments were conducted in a soil microcosm contaminated with 350 mg kg−1 of Zn and in an uncontaminated control microcosm, both incubated for 4 months. At regular intervals, potential nitrification, nitrate reductase, and β-galactosidase activity were determined. All these activities were significantly reduced just after Zn contamination in contaminated microcosms compared to the activities of the control, but then increased. In order to confirm that the restoration of ecological functions was not due to an aging phenomenon, a reinoculation protocol was also applied. A significant restoration was found for β-galactosidase activity, while for nitrate reductase activity and potential nitrification, there was a clear shift of dose–response curves but with partial overlap of the EC50 ranges estimation, thus indicating that different ecological functions are restored over time in Zn-contaminated soils.