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

Abstract

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 degradation and non-extractable or bound residues formation were evaluated after the application of ¹⁴C-atrazine in a Gley Humic soil. The processes were quantified by radiometric and chromatographic techniques in natural, sterilized and sterilized soil samples inoculated with Pseudomonas putida. The importance of microorganisms was observed through biomineralization studies, because the mineralization of ¹⁴C-atrazine was detected only in natural soil (about 15%). However, formation of extractable metabolites of atrazine was detected both in sterilized (67%) and natural (75%) soil samples, indicating that these processes were not dependent only on the presence of microorganisms. On the other hand, bound residues were formed in higher amount (about 56%) in sterilized soil.