Behavior of Atrazine and Its Degradation Products Deethylatrazine and Deisopropylatrazine in Oxisol Samples

Abstract

This work investigates the behavior of atrazine (AT) and its degradation products deethylatrazine (DEA) and deisopropylatrazine (DIA) in oxisol samples. The study was carried out at different depths of maize culture soil under no-till management for up to 180 days. Additionally, controlled laboratory experiments were performed in open flasks in the absence of sunlight or in closed flasks at 4 °C. Higher AT dissipation occurred in the in the field as compared with the samples evaluated under controlled conditions, which indicated that environmental conditions might degrade AT. Interestingly, DEA and DIA levels were low, which suggested that leaching and runoff processes, formation of other degradation products, or even AT mineralization took place. Residual AT, DEA, and DIA were detected in the oxisol samples after 180 days depending on the initial amount of AT in the soil. This study has shown that straw plays a relevant role in AT retention and significantly contributes to DEA and DIA formation. At 180 days, straw samples contained AT concentrations near 100 μg kg−1 and concentrations of the more leachable DEA and DIA close to 50 μg kg−1 even under the influence of sunlight and rainfall. A preliminary analysis of natural water samples near the investigated region showed that DEA and DIA were absent and that AT concentrations were high, which pointed to the need for more detailed evaluation.