Suwannee River

Burnett WC, Cowart JB, Deetae S (1990) Radium in the Suwannee River and estuary. Biogeochem 10 237-255... 

Leenheer, J. A., Wershaw, R. L. and Reddy, M. M. (1995). Strong-acid, carboxyl groups in fulvic acid from the Suwannee River, Georgia. 1. Minor structures,... 

Dixon, A. M. and Larive, C. K. (1997). Modified pulsed-field gradient NMR experiments for improved selectivity in the measurement of diffusion coefficients in complex mixtures application to the analysis of the Suwannee River fulvic acid, Anal. Chem., 69, 2122-2128. 

Averett RC, Leenheer JA, McKnight DM, Thorn KA (1987) Humic substances in the Suwannee river, Georgia interactions, properties, and proposed structures, Open-File Report 87-557, US Geological Survey, Denver, CO... 

Procedure. The procedure followed with XAD-8 was that of Thurman and Malcolm (8). The Suwannee River (GA) sample was filtered through 0.45-/zm Ag filters in Millipore, stainless steel, 142-mm, plate filter holders. The Laramie-Foxhills ground-water sample did not require filtration. Samples were processed on site within 24 h after collection to prevent alteration. All column eluates were adjusted to pH 2 upon collection and immediately refrigerated. 

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. 

In processing volumes of water as large as in the two examples cited, large columns of resin are preferred. In both the Foxhills-Laramie and Suwannee River samples, columns with 8 L of resin and a void volume of 6 L were used. By using eq 1 with a k cutoff of 100, it was calculated that, for the Foxhills-Laramie sample, 460 L of water could... 

This system has been employed quite successfully to process water samples in excess of 1000 L (Table III). In each of the examples cited, a 10-L column of A-7 resin was used with the exception of the Suwannee River sample, this quantity of resin was sufficient to process the entire sample without regenerating the resin. The method of Leen-heer and Noyes (10) differs from the XAD-8 method in that the filtered sample does not require adjustment to pH 2 before concentration. This... 

Correlation of Structure with Source. Allochthonous-derived DOM (8) was isolated from the Suwannee River at its origin in the Okefe-nokee Swamp in southern Georgia. The fiilvic acid fraction, which is responsible for the black coloration of the water, was extensively characterized (9). Several average molecular models based on quantitative analytical data were presented in that report (10) to denote the mixture characteristics of fiilvic acid. One model, modified to depict biochemical sources and based on quantitative analytical data (10), is presented in Structure 1. Other models of Suwannee River fulvic acid (based on lignins, terpenoids, tannins, and flavonoid sources) were previously proposed (II). 

Structure 1. One of several average structural models of fulvic acid from the Suwannee River, Georgia. 

DOM is derived from autochthonous sources such as phytoplankton and photosynthetic bacteria (16) at Big Soda Lake near Fallon, Nevada. This lake is alkaline (pH 9.7) and chemically stratified. It contains DOC concentrations as high as 60 mg/L and dissolved salt concentrations as high as 88,000 mg/ L (17). The DOM in this lake is colorless. The fulvic acid fraction was isolated by adsorption chromatography (Amberlite XAD-8 resin) (18) and by zeo-trophic distillation of water from N,N-dimethylformamide (19). Average molecular model synthesis was achieved in a manner similar to that used for fulvic acid from the Suwannee River. The characterization data are presented in Table I and the structural model is presented in Structure 2. 

The 14C age determination of the fulvic acid isolated rom water near the lake surface was 2300 years before the present, whereas the 14C age was 4900 years before the present for the fulvic acid isolated from water below the chemocline. These old ages for both fulvic acids from Big Soda Lake are in marked contrast to that reported for fulvic acid from the Suwannee River, less than 30 years before the present (11). The refractory nature of this type of fulvic acid derived from phytoplankton and photosynthetic bacteria is significant for carbon-cycling studies. 

Fulvic acid from the Suwannee River was used to calibrate peak-height ratios for aromatic carbon content. The application of this method to fulvic acid samples with known aromatic plus olefinic carbon content from various environments is shown in Table II. Aromatic plus olefinic carbon percentages calculated by the peak-height ratio method using lH NMR data closely agree with these percentages computed from 13C NMR data, with the exception of the Big Soda Lake samples. 

Determination Method Suwannee River above Fargo, GA Big Soda Lake near Fallon, NV Calcasieu River near Kinder, LA Mississippi River near St. Francisville, LA... 

Variation among Sampling Sites. Dissolved humic substance samples from seven end-member environments were isolated for study. Autochthonous inputs to DOM were expected to dominate in Big Soda Lake and in Island Lake, which is a groundwater-sustained eutrophic lake in the sandhills of western Nebraska. Allochthonous inputs to DOM from a swamp environment predominate in the Suwannee River. They also dominate in the Calcasieu River in western Louisiana, but the proportion of swampland is much lower there. The Temi River is a tropical blackwater tributary of the Orinoco River in Venezuela, where allochthonous inputs dominate. The entire Sagavanirktok River basin is located north of the tree line on the North Slope of Alaska a mixture of allochthonous and autochthonous inputs was expected for the various rivers and lakes in this basin. Lastly, Hidden Lake Creek, which is the outlet of Hidden Lake on the Kenai Peninsula of Alaska, was sampled to determine if nutrient inputs from decaying salmon were contributing to primary production and autochthonous inputs to DOM. 

Fulvic acid from Suwannee River above Fargo, Georgia 1.022 0.436 0.150 0.160 0.94 30.5... 

The Suwannee River was sampled at its origin at the outlet of the Okefenokee Swamp. This fulvic acid, therefore, is likely to be less degraded than a sample from the Calcasieu River that was taken near its mouth on the estuary during a warm, low-flow period in early summer. Metal-ion solubility controls and sorption on mineral surfaces in upland soils also might fractionate the fulvic acid in the Calcasieu River. In contrast, the Suwannee River mineral-soil solubility controls are less significant. 

Humic Substances in the Suwannee River, Georgia Interactions, Properties, and Proposed Structures Open-File Report 87-557 Averett, R. C. Leenheer, J. A. McKnight, D. M. Thom, K. A., Eds. U.S. Geological Survey Denver, CO, 1989 377 pp. 

TABLE III Differences in Chemical Properties of Suwannee River Fulvic Acid Sorbed onto Iron Oxide (Sorbable) and Suwannee River Fulvic Acid Remaining in Solution (Nonsorbable)... 

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