The Influence of Humic Substances from Drainage Waters on the Transportation of Anthropogenic Organic Chemicals

Humic Substances from Podzols Under Oak Forest and a Cleared Forest Site I. Isolation and Characterization

“…As stated already, the humic fractions isolated at pH 7 are generally more aromatic than those isolated at the higher pH values (Hayes, 1996). However, the highest ratio values were obtained for the HAs and the FAs isolated at pH 7.…”

“…The trends for N are less clear cut, and there are some striking differences in the N contents of the different samples. These are the most highly humified fractions, and have been shown in studies with non-podzol soil fractions to be the most aromatic of the fractions isolated at pH 7, 10.6, and 12.6 (Hayes, 1996). However, the N contents of the FAs isolated at pH 7 and pH 10.6 from the Bh horizon of the unforested soil are more The higher the H:C ratio values in hydrocarbons, the lower is the aromaticity and/or unsaturation.…”

“…HS were isolated [as humic acids (HAs), fulvic acids (FAs), and XAD-4 acids] using XAD-8 [poly(methyl methacrylate)] and XAD-4 (styrene divinylbenzene) resins in tandem, as described by Malcolm and MacCarthy (1992) and by Hayes (1996). Extraction was repeated with each solvent until the optical density values of the extracts were less than 1.…”

“…We await data for the amino acid (AA) contents of the humic fractions, but in general the highest contents of these are contained in the XAD-4 acids, and often in the humic fractions isolated from soils at the higher pH values (Hayes, 1996). The less well humified fractions are isolated at the higher pH values and these can contain the AAs of the partially humified substrates.…”

Humic Substances: Considerations of Compositions, Aspects of Structure, and Environmental Influences

“…The integrated areas for the resonances at 160-190 ppm (carboxyl, ester, amide) were 16%, 14%, and 12%, respectively, for these HA fractions, reflecting the expected decreases in carboxyl functionalities as the pH values of the extractants were raised. The contributions of amide functionalities to this resonance should not be overlooked because, for example, the contribution of amino acids to the overall composition of the HAs isolated at pH 12.6 was 16.3% (Hayes, 1996). The anomeric C resonances also increased as the pH of the extractant increased, indicating greater contributions of sugars to the compositions of the extracts.…”