Sorption and desorption of Atrazine in horizons of the Red-Yellow Latosol

Abstract

Background:

Studies of sorption and desorption of herbicides in soils are essential in predicting their transport, bioavailability, and transformation in the soil profile. These studies are also vital to predict the agronomic efficiency of the herbicides in controlling weeds.

Objective:

In this study, atrazine’s sorption and desorption kinetics were evaluated in samples composed of single and a mixture of horizons from the Red-Yellow Latosol profile.

Methods:

This was performed by the Batch equilibrium method, and the quantification was carried out using a High-performance liquid chromatography (HPLC).

Results:

Freundlich isotherms were adjusted appropriately to describe the atrazine sorption. The K_f values obtained varied between 0.188 and 2.592, and the Koc values ranged between 37.76 and 143.81, which corresponded to horizons C and A, respectively. The desorption was only possible to determine in horizon A. The other substrates presented low sorption, and the desorption of the remaining atrazine was not significant, therefore not adjusting to the Freundlich model. The organic matter (OM) was the main attribute to the atrazine sorption in the soil, presenting a high correlation with K_f and Koc values. In the horizon A samples, the K_fd value obtained in desorption was higher than the K_f obtained in sorption, which indicated a low desorption capacity and, therefore, low potential mobility of the herbicide in this soil horizon.

Conclusions:

It was concluded that the organic matter present in greater quantity in horizon A of the Red-Yellow Latosol has a crucial role in the dynamics of atrazine in the horizons of this soil.

Keywords:
Sorption kinetics; Freundlich coefficient; Chromatography