Uptake and Metabolism of Atrazine by Poplar Trees

Hybrid poplar trees can uptake, hydrolyze, and dealkylate atrazine to less toxic metabolites. In whole plant studies, the parent compound atrazine and 14 C ring-labeled metabolites were extracted from poplar tissues and analyzed via high-pressure liquid chromatography (HPLC) with UV and radiochromatographic detectors in series. The concurrent separation and identification of these metabolites has not been previously reported in higher plants for phytoremediation applications. Unidentified metabolites were also detected. Metabolism of atrazine occurred in poplar roots, stems, and leaves and became more complete with increased residence time in tissues. In poplar cuttings exposed to atrazine for 50 days, the parent compound comprised only 21% of the 14 C label in the leaves, while it constituted 59% of 14 C activity remaining in the soil. After 80 days, the parent compound remaining in the leaves had decreased to only 10% of the 14 C label recovered in the leaves. Preferred metabolic pathways were suggested by relative rates of reaction, and a mathematical model was developed to estimate rate constants for the proposed degradation mechanism. This research provides evidence for vegetative detoxification of contaminants and suggests that phytoremediation of atrazine-contaminated soils may be feasible.