Sorption kinetics of atrazine and diuron in soils from southern Brazil

• Published in: Journal of environmental science and health. Part B, Pesticides, food contaminants, and agricultural wastes Vol. 39; no. 4; pp. 589 - 601
• Main Authors: Inoue, M.H, Oliveira, R.S. Jr, Regitano, J.B, Tormena, C.A, Constantin, J, Tornisielo, V.L
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 2004; Taylor & Francis
• Subjects: Adsorption; agricultural soils; Agriculture; Agronomy. Soil science and plant productions; atrazine; Atrazine - analysis; Atrazine - chemistry; Biological and medical sciences; Brazil; carbon; crop rotation; diuron; Diuron - analysis; Diuron - chemistry; Elovich equation; equations; Fick's law; Fundamental and applied biological sciences. Psychology; Herbicides - analysis; Herbicides - chemistry; humid zones; isotope labeling; Kinetics; Leaching; liquid scintillation counting; no-tillage; pesticide persistence; Retention; Soil and water pollution; soil chemical properties; soil organic matter; soil physical properties; Soil Pollutants - analysis; soil pollution; Soil science; Sorption; subtropical soils; Water Pollutants - analysis; Brazil; South America; America; Brazil, Parana; Clay; Organic carbon; Cultivated soil; Pesticides; Diuron; Soil pollution; Retention; Leaching; Herbicide; Contamination; Sorption; Triazine derivatives; Ureas; Kinetics; Physicochemical properties; Fick's law; Atrazine
• ISSN: 0360-1234; 1532-4109
• DOI: 10.1081/PFC-200026818

Sorption kinetics of atrazine and diuron was evaluated in soil samples from a typical landscape in Paraná. Samples were collected (0-20 cm) in a no-tillage area from Mamborê, PR, which has been cultivated under a crop rotation for the last six years. Six sampling points of the slope were selected to represent a wide range of soil chemical and physical properties found in this area. Radiolabeled tracers ( 14 C-atrazine and 14 C-diuron) were used and the radioactivity was detected by liquid scintillation counting (LSC). Sorption was accomplished for increasing equilibration periods (0.5, 1.5, 3, 6, 12, 24, and 48 h). Kinetics data fitted adequately well to Elovich equation, providing evidences that soil reaction occurs in two distinct stages: a fast, initial one followed by a slower one. During the fast phase, 34-42 and 71-79% of total atrazine and diuron applied were sorbed to soil samples. No important differences were found among combinations of soil and herbicide sorption during the slow phase. The unrealistic conditions under batch experiments should be overestimating sorption in the fast phase and underestimating diffusion in the slow phase. Sorption of both herbicides was positively correlated to organic carbon and clay contents of soils, but atrazine was much less sorbed than diuron, showing its higher potential to contaminate groundwater, specially in sandy, low organic carbon soils.