Sorção-dessorção do fungicida clorotalonil em solos com diferentes teores de matéria orgânica

摘要: Pesticide kinetics and sorption allow to predict the equilibrium time of reaction speculate over mechanisms involved.Therefore, their study is fundamental understand environmental fate pesticides.The aim this research was evaluate fungicide chlorothalonil in five distinct soils with different organic matter contents state Sao Paulo (Brazil): Neossolo Quartzarenico ortico (RQo), Latossolo Vermelho distroferrico (LVdf-1 e LVdf-2), perferrico (LVj), Gleissolo (G).The experiments were performed a radiolabeled tracer, i.e., 14C-chlorothalonil, radioactivity being measured by liquid scintillation spectrometry.The carried out under controlled laboratory conditions (25±2oC), dark room. Kinetics evaluated for 8 periods: 0; 0.5; 1.0; 2.0; 4.0; 8.0; 12.0 24.0h. Desorption samples equilibrated 24hours, 4steps. For isotherm studies, concentrations ranged from 0.05 0.76µgmL-1.The Elovich equation fitted data whereas Freundlich studies.Chlorothalonil highly sorbed soils, except sandy soil low content (RQo).Sorption positively related content.Moreover, occurred two phases: very fast phase occurring first few minutes responsible most sorption, followed slow phase.The results show that small fraction applied would be available groundwater leaching, but special attention needed when it content.Furthermore, during may easily desorbed solution.