Degradation and formation of non-extractable or bound residues of the atrazine herbicide in soil

The persistence of a pesticide in soil depends on the dissipation processes , as degradation, that can be related with microbial metabolism. Aiming to evaluate the mechanisms of atrazine dissipation in soil, and the importance of the microorganisms in this process, its mineralization, intermediate de gradation and non-extractable or bound residues formation were evaluated af ter the application of C-14-atrazine in a Gley Humic soil. The processes we re quantified by radiometric and chromatographic techniques in natural, ste rilized and sterilized soil samples inoculated with Pseudomonas putida. The importance of microorganisms was observed through biomineralization studie s, because the mineralization of C-14-atrazine was detected only in natural soil (about 15%). However, formation of extractable metabolites of atrazin e was detected both in sterilized (67%) and natural (75%) soil samples, ind icating that these processes were not dependent only on the presence of mic roorganisms. On the other hand, bound residues were formed in higher amount (about 56%) in sterilized soil.