Humic and Fulvic Acid

Upland surface water. This is low in hardness salts having run over impervious rocks but will often be high in organic matter, i.e. fulvic and humic acids. 

Complexation by organic substances such as fulvic and humic acids... 

Transformation of the initially deposited remains of living organisms started in the water columns and in the upper layers of bottom sediments of ancient seas. Random polymerization and condensation reactions of degraded biopolymers are believed to have formed the initial geopolymers, which contain humin, fulvic and humic acids. Until now these compounds (very typical for soil humus as well) are... 

Beckett, R., Jue, Z. and Giddings, J. C. (1987). Determination of molecular weight distributions of fulvic and humic acids using flow field-flow fractionation, Environ. Sci. Technol., 21, 289-295. 

Weber and Wilson [3] used anion and cation exchange resins to isolate fulvic and humic acids from soil and water. 

Klenke et al. [5] described a technique for extraction of humic and fulvic acids from stream sediments and outlined methods for their determination. By means of flame atomic absorption spectrometry, the levels of environmentally important heavy metals (cadmium, copper, chromium, cobalt, nickel and lead) in the fulvic and humic acid extracts were compared with those in the original sediment samples. The pattern distribution of the respective metals in the two cases showed very close agreement, suggesting that the combined extract of humic and fulvic acids could be used as an indicator of the level of heavy metal pollution in flowing waters. 

The carbon contents in fulvic and humic acids are 45-50% and 50-55%, respectively The carbon content shows broader variations because of the strong carbon lattice, the concentration of carbon is as high as 65%... 

Fulvic and humic acids have been investigated with carbon-13 and proton nuclear magnetic resonance spectrometry, GC/MS, and IR spectroscopy. The fulvic and humic acids were found to be predominantly carboxylic and aromatic with a high proportion of 0- and Ji-substituted carbon atoms, although aliphatic ones were also observed. 

Preparation of Fulvic and Humic Acids. Waxes, resins, and other substances soluble in organic solvents were removed by successive extractions with petroleum ether (35-60°), chloroform, and ethyl acetate. These extractions removed of the original material. 

The insoluble material was removed by centrifuging at 5000 rpm for 15 min in a Beckman Model No J-6B centrifuge. This extraction with alkali was repeated twice more and the solutions of sodium salts of acids were collected. Humic acids were precipitated from the combined NaOH solutions by adjusting the pH to 1 with 2N HCl slowly with stirring and the mixture was left overnight. The precipitated humic acids were collected by filtration through Whatman IMM paper and washed with O.IN HCl. The filtrates were extracted three times with ethyl acetate and the extracts dried over sodium sulfate and evaporated, the residue constituting the fulvic acids. Buth fulvic and humic acids (precipitates) were air-dried, and then dried in a vacuum desiccator over phosphorus pentoxide at room temperature. 

Samples of both fulvic and humic acids were suspended in methanol and methylated with diazomethane. Both H and spectra of the free acids were obtained, at 299.94 MHz and 75.42 MHz respectively, on a Varian XL-300 spectrometer having a Nicolet TT-100 PET accessory. Spectra were obtained in D2O, in a 12-mm tube, with deuterated TSP (sodium 3-(trimethylsilyl)propionate-, , 3,3- 4) added as internal reference. GC/MS of methylated acids was conducted on a Hewlett-Packard Model No 5995 GC/MS/DA system equipped with a fused silica capillary column (12 m x. 020 mm ID, Hewlett Packard) internally coated with crosslinked methylene silicone. Infrared spectra were obtained with solid samples dispersed in KBr pellets, by using a Beckman IR-33 spectrophotometer. The various absorption peaks in IR and NMR were interpreted conventionally (9-10). 

KUMARIET AL. Fulvic and Humic Acids of Minnesota Peat... 

Both and nmR showed the presence of aromatic and aliphatic components. In l C-NMR, resonances at =58 ppm indicate the presence of many OCH3 groups, such as those occurring in syringic, vanillic, and ferulic acids. Spectra clearly show the presence of palmitic and stearic acids by GC/MS, IR, and NMR data. The fulvic and humic acids are predominantly made up of phenolic and fatty acid units. These are highly aromatic because lignin residues have been incorporated in the humification process. 

Fig. 5.1. Scheme of separating the soil fulvic and humic acid fractions. 

The weight of ash-free humic acid was derived from 10 g air-dry soil, therefore should be multiplied by 10 to convert to percent air-dry soil and further converted to percentage oven-dry soil. The fulvic and humic acid content may be expressed as a percentage of total soil organic matter, which is quantified as soil organic carbon (SOC). SOC is conveniently determined from the loss on ignition, where the correlation is ... 

T HE PRESENCE OF ORGANIC CONSTITUENTS IN DRINKING WATER has been known for many years because these substances were found to influence the taste, color, and odor of drinking waters (J). The organic constituents consist of compounds of both natural and industrial origin. The natural ones compose the major portion and include mainly undefined fulvic and humic acids (2). For the industrial ones, most attention has been paid so far to the volatile nonpolar compounds. In part, this situation is due to analytical (technical) restrictions and to the growing awareness (3, 4) that volatile halogenated hydrocarbons are introduced as a result of a chlorine treatment. 

Fulvic and humic acid from Temi River, blackwater tributary of Orinoco River, Venezuela 0.820 HOD—solvent peak interferes 0.250 0.250 1.00 47.7... 

CARBOXYLIC AND PHENOLIC ACIDS 22.2.1 Fulvic and Humic Acids... 

Table 2 Typical Compositions of Oxygen Functional Groups in Fulvic and Humic Acids (mmolg-1)166...

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