Modeling nitrification inhibition

A quantitative structure-activity relationship (QSAR)-type model using groups and molecular connectivity has been developed on nitrification inhibition data derived from soil. The model has been tested against data derived from the inhibition of nitrification by specific nitrogen-containing pesticides. A second QSAR-type model developed from acclimated biodegradation data has been applied to the pesticides tested for nitrification inhibition. Data on the impact of specific compounds on activated sludge nitrification have been included and the soil model applied to these activated sludge data. In general, the agreement between predicted and observed values for nitrification inhibition was satisfactory. The agreement was only marginal with respect to the biological system data. The biodegradation model indicated that most of the strong inhibitors also would have prolonged existence in the open environment. The models are included in the paper as well as the specific methodology.