Sorption behaviour of atrazine on agricultural soils of different characteristics: equilibrium and kinetics studies

The study aimed to investigate how the herbicide atrazine (2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) interacts with agricultural soils: black soils (BS-1, BS-2, BS-3) and red soils (RS), under three different temperature conditions using batch equilibrium method. The findings of the study indicated that the sorption kinetics of this herbicide in soils can be divided into two-stages: quick initial sorption followed by relatively slower sorption. These results have been explained well by the pseudo-second-order kinetic model. The Freundlich model provided a good description of the sorption isotherms. The highest sorption was reported in BS-2 soil, followed by BS-3, RS and BS-1 soils. Organic matter of soil, percentage of clay, specific surface area, and cation exchange capacity could be the factors responsible for sorption as it showed a positive correlation with the partition coefficient (K_d) and Freundlich constant (K_f). All investigated soils exhibited a favourable condition for atrazine sorption under low pH levels. The sorption of atrazine was noticeably affected by temperature. Higher temperatures caused atrazine to become more mobile, resulting in reduced sorption on the studied soils, with an increased risk of leaching. The low values of K_f (Freundlich constant) and K_oc (organic carbon partition coefficient) indicate that atrazine exhibits high mobility in all soils, which raises concerns regarding the potential contamination of groundwater resources.