Adsorption and Desorption Behavior of Chlorotriazine Herbicides in the Agricultural Soils

Abstract

The chlorotriazine herbicides have been applied worldwide for controlling of broadleaf weeds. These herbicides are known carcinogen and thus, their occurrence in surface and ground water is a cause of concern. In the present study, adsorption–desorption behavior of chlorotriazine herbicides namely simazine and atrazine was investigated. For the study, two different types of agricultural soil A (loam, 13.7% organic matter content) and soil B (clay-loam, 4.8% organic matter content) was collected from Punjab, India. The adsorption–desorption study was carried out by batch equilibration procedure. The data fitted well into the Freundlich equation. The adsorption Kf values indicated that the simazine has more soil adsorption ability than atrazine. The extent of herbicides adsorbed to the soil was more under low pH conditions and decreased with the increase in pH value. Increase in temperature decreased herbicides adsorption ability for both the soil types. The Gibb’s free energy (ΔG) values were found less negative with the increase in temperature. Atrazine exhibited better desorption behavior than simazine. Soil A with high organic matter content exhibited sorption–desorption hysteresis. The results indicate that the soil organic matter content and aqueous solubility play an important role in the adsorption–desorption behavior of chlorotriazine herbicides. The present understanding of chlorotriazine herbicides sorption–desorption process will help to determine the herbicides fate and availability in soil, biodegradation, runoff and leaching.