Laramie-Fox Hills aquifer

The nitrogen content of humic substances from groundwater is similar to that of humic substances from surface water. Data from the St. Peters and Laramie-Fox Hills aquifers suggest that the nitrogen content of humic substances from groundwater may be somewhat lower than the average nitrogen... 

Humic substances from groundwater are considerably less colored per unit of carbon than humic substances from surface water their absorbance at 465 nm (a wavelength commonly used for color in Standard Methods, 1971) is 3-10 times less than the absorbance of humic substances from surface water. Table 6 compares absorbances of humic substances from groundwater with absorbances of humic substances from surface water. Absorbances of samples from the Red River, St. Peters, and Laramie-Fox Hills aquifers are considerably less than absorbances of humic substances from an average surface water. Only the Madison and the Biscayne samples are similar in color to humic substances from surface water. The Biscayne is... 

FIGURE 2. Infrared spectra of fulvic acid from the Madison (A), St. Peters (B), and Red River (C) aquifers, and of humic and fulvic acids from the Laramie-Fox Hills aquifer (D and E, respectively) (Thurman, 1979). 

Other evidence supporting the kerogen hypothesis is that kerogen is enriched in carbon and hydrogen and depleted in oxygen, as is the case for humic substances from the Red River, Madison, St. Peter, and Laramie-Fox Hills aquifers. The only conflicting evidence is the fractionation,... 

An extraction method for isolating humic substances from water by using XAD-8 has been proposed by Thurman and Malcolm (9) (see box). Humic substances in natural waters represent almost the entire hydrophobic acid fraction. This method has been used to isolate 4.25 g of humic substances from 24,500 L of ground water from the Fox-hills-Laramie aquifer and to obtain 500 g of humic material from 10,400 L of the Suwannee River (Table II). The sample from the Suwannee River was collected as a reference sample of aquatic humic substances by the International Humic Substances Society. In both of the examples cited, a fc cutoff of 100 was used. 

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