Atrazine mineralization in laboratory-aged soil microcosms inoculated with s-triazine-degrading bacteria.
1997
Radosevich M. | Traina S.J. | Tuovinen O.H.
An atrazine (2-chloro-4- ethylamino-6-isopropylamino-s-triazine) -mineralizing bacterial isolate was used as a biological probe to investigate the effects of atrazine residence time on subsequent bioavailability and biodegradation. [U-14C-ring]-atrazine was reacted with sterile soils collected from long-term, experimental, no-till and conventional-tillage plots. After aging for 1 d to 3 mo, the atrazine-treated soils were inoculated with the bacterium (7 X 10(7) cells g-1) and 14CO2 evolution was measured with time. Mineralization of [U-14C-ring]-atrazine could be described with a first-order rate equation in soils from both tillage systems. Atrazine was rapidly mineralized in no-till soil aged for 1 d, with 50% of the initial radioactivity recovered as 14CO2 within 2 d after inoculation. Both the mineralization rate constants (k) and the extent of mineralization (Pmax) decreased with soil residence time. In conventional-till soil, no significant aging effect was observed for soil reacted for 7 d; however, both the k and P values decreased with extended aging. Measurements of soil solution-phase atrazine were determined by high-pressure liquid chromatography analysis after solutions were retrieved by centrifugation. In no-till soil, the observed degradation rates were 38 to 227 times slower than those predicted on the basis of solution-phase experiments. The respective rates were 25 to 63 times slower in the conventional till soil. The results suggest that a significant fraction of the solution-phase atrazine was sequestered from microbial attack and that the unavailable fraction increased with soil residence time.
Afficher plus [+] Moins [-]Mots clés AGROVOC
Informations bibliographiques
Cette notice bibliographique a été fournie par Wolters Kluwer
Découvrez la collection de ce fournisseur de données dans AGRIS