Satilla River

Total Acidity. The procedure proposed by Schnitzer and Gupta (13) and Schnitzer and Kahn (14) was adopted with some modification for the determination of total acidity (TA). All operations were carried out under N2 atmosphere. Accurately weighed samples of approximately 10 mg were used for this determination. A blank experiment and six repetitive analyses from the Satilla River were performed. The mean value was 11.1 meq/g s = 0.35 and cv = 3.2 were calculated. 

Spectral Studies. UV ABSORPTION. The acetone fractions derived from drinking water exhibited intense UV absorption between 208 and 214 nm this behavior may be attributed to unsaturated acids or esters. The CFH samples presented maximum absorption at 254-256 nm, whereas an aquatic humus sample derived from the Satilla River showed a maximum absorption at 234 nm. Therefore, apparent differences in UV spectra among all sample groups were found. 

FLUORESCENCE Spectra. Fluorescence data are presented in Table V. All samples derived from drinking water gave an emission maximum between 417 and 430 nm, whereas the excitation maximum ranged between 346 and 365 nm. Miami IB showed an excitation maximum similar to the CFH samples, but the maximum was quite different from the one exhibited by the aquatic humic substances from the Satilla River. The emission maximum of these samples (Table V), however, was very similar. 

IR SPECTRA. The IR spectra of all 10 samples derived from drinking water are almost identical. Figure 1 shows a representative spectrum. For comparison, the IR spectra of Satilla River aquatic humus and CFH are added. All samples exhibited broad bands in the 3400-cm 1 (—OH), 1720-cm"1 (C=0), and 1640-cm 1 (C=C) regions. However, the spectra from the 10 drinking water samples and CFH samples showed distinct differences from that of the Satilla River aquatic humus, which absorbs sharply near 1600 cm-1. This result suggests that the samples derived from drinking water are strongly altered by chlorination and/or oxidation. Further confirmation of the spectral dissimilarities should be pursued by analysis of chlorinated alteration products of humus. 

Humic Satilla River water Solar simulator, 4 h = mid-June sun at 34oN 0.1 0.011 0.25 Not measured Gao and Zepp (1998)... 

Cai, W.J., Wiebe, W.J., Wang, Y., and Sheldon, J.E. (2000) Intertidal marsh as a source of dissolved inorganic carbon and a sink of nitrate in the Satilla River estuarine complex in the southeastern U.S. Lirnnol. Oceanogr. 45, 1743-1752. 

Because of the considerable potential of titration calorimetry as an analytical technique for characterization of the acidic functional groups of humic substances, our studies have been extended to river water humic substances. In this paper, results are presented for the thermochemical characterization of the acidic functional groups of river water humic substances from two quite different river systems 1) the Satilla River in southeastern Georgia, and 2) the Williamson River in southern Oregon. 

Williamson River humic substances (WR-HS) Satilla River humic substances (SR-HS) soil humic acid (Soil HA). 

Figure 2. Thermometric titration curves for neutralization of (%) Williamson River humic substances and (O) Satilla River humic substances with NaOH...

Perdue et al. (1976) observed an excellent linear correlation between the combined concentrations of Fe and Al and DOM in the Satilla River system (southeast U.S.A.). Such a correlation is likely to result from the formation of dissolved organic complexes rather than the adsorption of DOM onto colloidal iron hydroxide particles. Furthermore, using vapour pressure osmometry, Perdue et al. (1976) determined the number-average molecular weight of the DOM to be 1296, thus enabling them to derive an (Fe + Al) DOM stoichiometric binding ratio of 0.8—1.1, in agreement with the values for soil... 

Figure 5.3 Calculated values of partial pressure of CO2 (/>C()2), based on dissolved inorganic carbon (DIC) and pH data, versus salinity in estuarine waters of the Satilla and Altamaha Rivers (USA). (Modified from Cai and Wang, 1998.)...

In addition to alkalinity inputs from rivers, estuaries can also receive inputs from bordering wetlands. For example, Cai et al. (1999) have shown that respiration rates in rivers/estuaries of Georgia (USA) cannot account for O2 consumption and CO2 degassing. It has since been shown that the missing DIC source is from marshes in the Satilla estuary (USA) (Cai et al., 2000). Other studies have also shown that intertidal marshes are important sources of DIC in estuaries (Raymond et al., 1997, 2000 Neubauer and Anderson, 2003). It has been further suggested that CO2 fixation of marsh grasses and the subsequent export of DIC and organic C to the coastal ocean can be described as... 

Cai, W.J., and Wang, Y. (1998) The chemistry, fluxes and sources of carbon dioxide in the estuarine waters of the Satilla and Altamaha Rivers, Georgia. Lirnnol. Oceanogr. 43, 657-668. 

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