Atrazine degradation and residues distribution in two acid soils from temperate humid zone.
Mineralization of atrazine and formation of extractable and non-extractable "bound" residues were followed under laboratory conditions in two contrasting soils (organic C, texture, and atrazine application history) from northern Spain. The soils, a Humic Cambisol (MP) and a Gleyic Cambisol (G) were incubated with labeled atrazine (ring-13C atrazine) at field application dose and measurements were made at different time intervals during 3 mo. Fate and behavior of atrazine along the incubation showed different patterns between the two soils, the time taken for degradation of 50% (DT50) being 9 and 44 d for MP and G soils, respectively. In MP soil, with 40 yr of atrazine application and lower organic C and clay content, more than 89% of U-13C-atrazine added was mineralized after 12 wk, with most mineralization occurring within the first 2 wk. G soil, with 10 yr of atrazine application, exhibited a more progressive U-13C-atrazine mineralization, reaching 54% of initially added atrazine at 12 wk. Hydroxyatrazine and deisopropylatrazine were the metabolites founded in the extractable fraction, demonstrating that both chemical and biological processes are involved in atrazine degradation. Soil G showed during all the incubation times an extractable residues fraction greater than that in MP soil, indicating a high potential risk of soil and water contamination. Rapid microbial degradation through s-triazine ring cleavage was proposed to be the main decomposition pathway of atrazine for the two soils studied. Bound residues pool also differed notably between soils accounting for 9 and 41% of initially added atrazine, the higher values shown by soil with higher organic matter and clay content (G soil).
Mahía
J
J
Departamento de Bioquímica del suelo, Instituto de Investigaciones Agrobiológicas de Galicia (CSIC), Avda Vigo s/n, Apartado 122, E-15780 Santiago de Compostela, Spain.
Díaz-Raviña
M
M
D001280:Atrazine / Q000031:analogs & derivatives / Q000737:chemistry*; D002980:Climate; D006813:Humidity; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010573:Pesticide Residues / Q000737:chemistry*; D012987:Soil / Q000032:analysis*; D013030:Spain; D013997:Time Factors; D014227:Triazines / Q000737:chemistry
C445502:6-chloro-N-ethyl-1,3-5-triazine-2,4-diamine; D010573:Pesticide Residues; D012987:Soil; D014227:Triazines; C027881:2-hydroxyatrazine; D001280:Atrazine