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thirty-four papers concerning the persistence of 2,4-D in water under 

 both laboratory and field conditions and concluded (1) under laboratory 

 conditions, 2,4-D repeatedly decomposed in water in periods of hours to 

 days; (2) under some warm water field conditions, 2,4-D has repeatedly 

 been shown to be reduced to non-detectable levels (low ppb range) in 

 closed water bodies in approximately one month; and (3) persistence of 

 2,4-D at extremely low levels may be encouraged by water movements in 

 lakes, reservoirs, and streams. Joyce and Sikka (1977) randomly moni- 

 tored 2,4-D levels in a large riverine system for seven months in con- 

 junction with routine waterhyaci nth control operations utilizing 2.24 

 to 4.48 kg(a.e.)/ha 2,4-D DMA and reported 2,4-D levels from non- 

 detectable to 1.3 jjg/1 . Smith and Isom (1967) reported similar residue 

 levels in large freshwater reservoirs in the Tennessee Valley in con- 

 junction with Eurasian watermilfoil ( Myriophyllum spicatum L.) treatments 

 at 44.8 to 112.0 kg(a.e.)/ha 2,4-D BEE. Schultz (1973) reported that 

 2,4-D DMA persists in the hydrosoil at the mg/1 level for about one 

 month, whereas Smith and Isom (1967) documented the persistence of 2,4-D 

 BEE in hydrosoil at 58.8 mg/kg 10 months after treatment. Hemmett and 

 Faust (1969) demonstrated that biodegradation of 2,4-D follows zero- 

 order kinetics, with the oxidation rate independent of substrate 

 (2,4-D) concentration. The rate was dependent upon (1) period of time 

 in which the system has acclimatized to 2,4-D; and (2) the natural con- 

 dition of the aquatic environment. The various formulations of 2,4-D 

 also do not persist or bioaccumulate in fish (Schultz, 1973; Whitney et 

 al., 1973; Sikka et al . , 1977; Halter, 1980), blue crabs, Callinectes 

 sapidus (Joyce and Sikka, 1977) and benthic invertebrates (Whitney et 

 al., 1973; Halter, 1980). Hildebrand (1946) during the first documented 



