Accelerated degradation of (14)C-atrazine in brazilian soils from different regions.
The repeated use of a given pesticide may induce a selection of the soil microbial population, resulting in a rapid degradation of the respective xenobiotic. Patterns of atrazine degradation (mineralization, formation of metabolites and nonextractable residues (NER)) were evaluated in two Brazilian soils with a history of atrazine application. Results were compared with those obtained from soils that had no agricultural use or herbicide application history. (14)C-Atrazine mineralization in unsaturated treated soils was high. By the 85th day of incubation, 82% of the applied (14)C-atrazine was mineralized in the Rhodic Hapludox and 74% in the Xanthic Haplustox. Mineralization remained low in nontreated soils (<or=5.1%). Incubation under slurry conditions enhanced atrazine mineralization in the treated Xantic Haplustox and surprisingly also in the nontreated Rhodic Hapludox (98 and 83% on the 85th day, respectively), whereas in the other samples the evolved (14)CO(2) did not differ (p < 0.05) from the unsaturated conditions. The water-extractable amount of atrazine directly after (14)C-atrazine application was higher in both Xanthic Haplustox samples (around 80% of applied atrazine) in comparison to the Rhodic Hapludox samples (around 60%). Extractable activity and the formation of metabolites and NER varied among the studied soils according to the atrazine application history rather than the soil characteristics.
Martinazzo
Rosane
R
Department of Soil Science, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. martinazzo_ro@yahoo.com.br
Jablonowski
Nicolai D
ND
Hamacher
Georg
G
Dick
Deborah P
DP
Burauel
Peter
P
D001280:Atrazine / Q000032:analysis*; D001938:Brazil; D002247:Carbon Isotopes / Q000032:analysis; D006540:Herbicides / Q000032:analysis*; D012987:Soil / Q000032:analysis*
D002247:Carbon Isotopes; D006540:Herbicides; D012987:Soil; D001280:Atrazine