hydrolysis rate constant of 2,4-DOE were observed. These observations are mutually consistent with a rapid, reversible partitioning of 2,4-DOE between water and "dissolved" humic substances. The humic-bound 2,4-DOE is not adsorbed to glass and is protected from alkaline hydrolysis. On the basis of this model, with aquatic humus concentrations expressed as g of C/g of H20, the distribution coefficient of 2,4-DOE between water and aquatic humus (Kb) was calculated from both the glass adsorption data and the alkaline hydrolysis data, yielding log Kb values of 4.4 and 4.8, respectively.From the magnitude of the distribution coefficient of 2,4-DOE between water and "dissolved" humic substances, a significant interaction is generally expected for hydrophobic compounds in natural waters. Rates of alkaline hydrolysis, volatilization, etc., would be expected to be reduced in proportion to the fraction of a hydrophobic solute that is associated with humic substances.If any general acid-base catalysis of the hydrolysis reaction is attributable to humic substances, that contribution is completely masked by the partitioning phenomenon, which strongly decreases the rate of alkaline hydrolysis of 2,4-DOE.

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