On the photolysis of selected pesticides in the aquatic environment

Abstract
The photodegradation (UV λ > 290nm) of the herbicides atrazine and diuron was examined in distilled water and artificial seawater containing humic acids. Major photodegradation products were hydroxyatrazine and monuron, respectively. The results showed a faster degradation in seawater as compared to distilled water for atrazine whereas for diuron a quenching effect was observed thus retarding photodegradation. The photodegradation of fenitrothion was also investigated. For this pesticide, the hydrolysis predominates in seawater whereas the photolysis is very slow in distilled water, so that acetone was needed as photosensitizer. The advantages of direct analysis of water samples by liquid chromatography with diode array and mass spectrometric detection is illustrated.