Factors influencing the transformation of S-triazine herbicides in Moroccan soil

S-triazine herbicides are widely used for preemergence and postemergence we ed control. In order to understand the behaviour of s-triazines herbicides in soil, it is necessary to know the processes which govern the persistence and the transformation of this compounds in water, soil and air. Photochem ical investigations in aqueous solution constitute a considerable interest for the mineralization, transformation and the elimination of pesticides in different environmental compartments. Under simulated solar light (lambda greater than or equal to 290nm), the half life of terbuthylazine in distill ed water with and without humic substances are 8.01 hours and 23.1 hours re spectively with a first order kinetic. In soil and in aqueous solution at l ambda greater than or equal to 290nm, dealkylation is the most important pa thway of degradation of terbuthylazine, the conversion products are desethy lterbuthylazine and desisobutylterbuthylazine.