Studies on mobility and degradation pathways of terbuthylazine using lysimeters on a field scale

The degradation pathways of Terbuthylazine in agricultural soils were evaluated by following the appearance and mobility of its main transformation products: dealchylated and hydroxylated derivatives. Three experimental studies degradation in open field conditions were carried out in different hydraulic conditions: constant hydraulic head was achieved on the topsoil thus simulating the worst risk situation for aquifer, intermittent artificial precipitation simulated a medium risk situation, while natural precipitation represented the lowest risk condition. Concentrations of terbuthylazine transformation products derived from dealkylation and hydroxylation reactions were measured in lechates and soil samples collected during the three experiments. DET and DETH metabolites of Terbuthylazine were found to be the most leaching compounds and therefore can be considered as potential pollutants for aquifer contamination