Phytoremediation is the use of vegetation for in-situ treatment of contaminated soils, sediments and groundwater. Hybrid poplar trees have shown the ability to tolerate and metabolize many organic chemicals that have been assimilated into plant tissues through the roots. High-volume acetanilide herbicide use in the Midwest has resulted in both point source and non-point source contamination of shallow groundwater and surface waters. Engineered planting of hybrid poplar trees may be able to intercept and treat herbicide contaminated ground water. Laboratory studies involving hydroponic microcosms and isotopically labeled herbicides will determine plant toxicity and fate pathways for various herbicide mixtures. Mass balances will be completed and the identities of metabolites will be determined using a variety of analytical techniques. The project will test the efficacy of hybrid poplar tree use to remediate contaminated agrichemical facilities.