Persistence and Fate of 2,4-D Butoxyethanol Ester in Artificial Ponds1
- Brendan C. Birmingham and
- Brian Colman2
A granular formulation of the butoxyethanol ester of 2,4-dichlorophenoxyacetic acid (2,4-D) was applied at a rate of 23 kg a.i. ha−1 to outdoor, artificial, polythene-lined ponds infested with Eurasian watermilfoil (Myriophyllum spicatum L.). Water temperature dropped from 25°C at time of treatment to 0°C after 56 d and the ponds were frozen over for the rest of the study. Samples of plant material, pond water, and sediment were taken over a 180-d period, extracted, and analyzed by gas chromatography to determine residue concentrations of ester and 2,4-D. Ester levels in water were low and dropped to < 1.0 µg L−1 within 15 d. Ester concentration in sediment 7 d post application was 1.7 µg g dry wt−1, but dropped to 0.1 µg g dry wt−1 after 42 d. 2,4-Dichlorophenoxyacetic acid residues in water declined to 1.0 mg L−1 after 85 d and to 0.2 mg L−1 after 178 d. Residues in plant material dropped to 10 µg g dry wt−1 after 70 d; sediment residues were negligible after 50 d. Residues of 2,4-dichlorophenol or 2,4-dichloroanisole were not detected in any samples. Despite the low temperature prevailing in the latter half of the study, a relatively rapid rate of 2,4-D breakdown was maintained both in pond water and sediment.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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