Aminocyclopyrachlor sorption-desorption and leaching from three Brazilian soils

摘要

This study aimed to evaluate the sorption-desorption and leaching of aminocyclopyrachlor from three Brazilian soils. The sorption-desorption of (14)~C-aminocyclopyrachlor was evaluated using the batch method and leaching was assessed in glass columns, The Freundlich model showed an adequate fit for the sorption-desorption of aminocyclopyrachlor. The Freundlich sorption coefficient [K_(f (sorptiOn))] ranged from 0.37 to 1.34 μmol~(1-1) L~(1) kg~(-1) and showed a significant positive correlation with the clay content of the soil, while the K_(f (desorption)) ranged from 3.62 to 5.36 μmol~ (1-1n) L~(1) kg~(-1) The K_(f (desorption)) values were higher than their respective K_(f (sorPtion)). indicating that aminocyclopyrachlor sorption is reversible, and the fate of this herbicide in the environment can be affected by leaching. Aminocyclopyrachlor was detected at all depths (0-30 cm) in all the studied soils, where leaching was influenced by soil texture. The total herbicide leaching from the sandy clay and clay soils was <0.06%, whereas, ~3% leached from the loamy sand soil. The results suggest that aminocyclopyrachlor has a high potential of leaching, based on its low sorption and high desorption capacities. Therefore, this herbicide can easily contaminate underground water resources.