Humic acid distribution coefficient

TABLE 4.6. Freundlich Adsorption Constants (1In and K) and Distribution Coefficients (Kd) for Adsorption of Alachlor (Generally Linear Isotherms), Imazethapyr (Nonlinear Freundlich Isotherms), and Rimsulfuron (Langmuir Isotherms) on Humic Acids (HAs) Isolated from Two Sewage Sludges (SSI and SS2), a Soil Amended with 10tha 1yr 1 of SSI for 2 Years (SOI + SSI), and a Soil Amended with 40(ha 1yr 1 of SS2 for 2 Years (S02 + SS2), with the Corresponding Unamended Soils (SOI and S02, Respectively) (from Senesi et al., 2001)... 

Flow field-flow fractionation (flow FFF) was developed by Beckett and Hart (1988) to determine the MW distribution of humic and fulvic acid. This method determines the diffusion coefficient which is then correlated to the MW with standards of known solutions, such as polystyrenesulphonate. A different result was obtained, compared to size exclusion chromatography when using Aldrich humic acids. In Becketts study the complexity of this kind of analysis is demonstrated by Beckett and Hart (1988) and different methods are questioned. 

These data indicate that the tendency to distribute into the DOM varies both with the nature of the compound and the DOM. The soil humic acid was a more effective receptor and the magnitude of the Adom was directly related to the octanol-water partition coefficient, Aqw, which is also an index of a compound s tendency to distribute into a hydrophobic environment. Experiments with 1,2,3-trichlorobenzene (log Aqw = 4.14) and lindane (log = 3.70) did not give the same degree of solubility enhancement. Note that the distribution constant for DDT based on organic carbon, A[Pg.32]

FIGURE 18.2 (See color insert following page 300.) Chemical space plot of the phase distribution of different chemicals in a dry snow pack as a function of the snow surface/air sorption coefficient (log ATiA/m) and the humic acid/air partition coefficient (log / ha/a)- IA and Kha/A values were determined based on Roth et al. (2004) and Niedeier et al. (2006). 

Morris, K. F., Cutak, B. J., Dixon, A. M., and Larive, C. K. (1999). Analysis of diffusion coefficient distributions in humic and fulvic acids by means of diffusion ordered NMR spectroscopy. Anal. Chem. 71, 5315-5321. 

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