ENVIRONMENTAL DEGRADATION OF ATRAZINE, LINURON AND FENITROTHION IN SOIL SAMPLES

The persistence of atrazine, linuron and fenitrothion in soil samples from an estuarine area (Ebro delta, Tarragona, Spain) has been studied. Soil samples from the top surface (10 cm) were collected during 1989-91, freeze-dried, sieved through 200 mum, Soxhlet extracted with methanol, cleaned-up with Florisil and analysed either by gas chromatography-nitrogen phosphorus detection (GC-NPD), in the case of atrazine and fenitrothion, or by liquid chromatography with diode array detection (LC-DAD), for linuron. Confirmation of the samples analysed by GC-NPD was carried out using GC-mass spectrometric detection (MS) in the electron impact mode. The soil half lives obtained under the real environmental conditions have been calculated and the values obtained have been correlated with the physicochemical properties of each pesticide and the soil type. Degradation was affected by volatilization since temperatures in the area of study are relatively high, ca. 30-degrees-C, in the summer period. In the case of atrazine it has been shown that deethylatrazine is formed in all the samples studied..