Atrazine Degradation in Two Soil Profiles

Abstract

Degradation of 2-chloro-4-ethylamino-6-isopropyl-s-triazine (atrazine) was studied in the 0 to 9, 14 to 24, and 36 to 48-inch depths of Sharpsburg silty clay loam and Keith silt loam soils. The effects of moisture, temperature, and microorganisms on degradation were observed. Atrazine was degraded two to three times faster in the topsoils than in the subsoils. Each 10 C temperature increase from 15 to 35 C caused the degradation rate to increase two to three times in these soils. Increasing the moisture content of the soils from 0.4 to 0.8 field capacity caused ¹⁴CO₂ evolution from chain-labeled atrazine-¹⁴C treated soils to increase zero to six times. At 25 C and 0.8 field capacity, 100 to 194 atrazine molecules were detoxified for each molecule evolved as ¹⁴CO₂ from chain-labeled atrazine. Solution culture studies showed cleavage of the side chain and ring of atrazine-¹⁴C except in the 14 to 24 and 36 to 48-inch depths of Keith silt loam.