Atrazine fate in Rhodic Ferralsol grown with corn under high-intensity rainfall conditions

Abstract

This research aimed to evaluate the possible runoff and leaching of atrazine in corn crops during high-intensity rainfall and the influence of summer and winter seasons on this herbicide's environmental distribution. Leaching and suction lysimeters were used, with atrazine mobility evaluated during simulated precipitations 24 and 48 h after the atrazine spraying during corn development during the summer and winter seasons for two years. Adsorption studies at the laboratory were conducted to understand soil adsorption better. The Kd and KOC at 25 ºC of 2.59 L Kg−1 and 281.64 L Kg−1 indicate moderate atrazine retention, with soil adsorption being exothermic, reversible, and spontaneous. Multilayer adsorption of atrazine is enhanced by soil organic matter by about 20.3%. During winter, atrazine retention in soil increases by 2.2x, while its loss by runoff and leaching decreases by 6.75 and 3.0x. Losses by runoff during rainfall simulations are 14.5x greater at 24 h than 48 h after spray, while atrazine loss by leaching is 1.7x greater at 48 h than 24 h after spray. Runoff or leached water contained much higher levels of atrazine than the acceptable national or international standards for drinking water, natural waters, or effluent discharge, indicating that extreme weather could increase environmental contamination.