Dissolved inorganic carbon components

Over the last several decades, the decline in alkalinity in many streams in Europe and in northeastern USA as a result of acid deposition has been a subject of much concern (Likens et al., 1979). The concentration of bicarbonate, the major anion buffering the water chemistry of surface waters and the main component of dissolved inorganic carbon (DIC) in most stream waters, is a measure of the reactivity of the watersheds and reflects the neutralization of carbonic and other acids by reactions with silicate and carbonate minerals encountered by the acidic waters during their residence in watersheds (Garrels and Mackenzie, 1971). Under favorable conditions, carbon isotopes of DIC can be valuable tools by which to understand the biogeochemical reactions controlling carbonate alkalinity in groundwater and watersheds (MUls, 1988 Kendall et al., 1992 see Chapter 5.14). 

Fig. 1 Simplified Eh-pH diagram showing stability fields of common iron minerals. The stability fields change position slightly depending on the activity of the components. In this case Fe2+, Fe1 and S = 10"6mol I" and dissolved inorganic carbon = 1 mol K After Garrels and Christ (1965).

In the hydrosphere, carbon is present as dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC), and the marine biota (Table 5.2). The amount of carbon present in each of these components is estimated to be 3 Pg in biota, 1,000 Pg as DOC, 30 Pg as POC, and 37,900 Pg as DIC. 

Ogura and Hanya [62-65] investigated the components of the ultraviolet absorption in an attempt to devise a useful method for oceanic dissolved organic carbon measurements. They concluded that while the method might have limited application in coastal waters, most of the absorption in oceanic waters was due to the inorganic components, principally nitrate and bromide ions. 

Water is modified by soil when added as either rain or irrigation [2], The modifiers are plants, plant roots, organic matter, organic matter decomposition products, carbon dioxide and other gases in the soil atmosphere, and dissolved inorganic compounds, commonly salts. Of particular importance is the change in pH that accompanies this modification of water. Thus, components obtained from soil by added extraction water will be significantly different from... 

In the lower reaches of the Genesee River, the results of the extractions suggest that substances other than hydrous oxides are phosphorus sinks. This is evident where the amount of sediment phosphorus extracted by hydrochloric acid steadily increases down river, while the oxalate extractable phosphorus remains relatively constant. Schwertmann (2 ) emphasized that the results of such procedures are best considered as a measure of the relative amount of a phase or, more generally, a measure of an element s reactivity in a sediment under carefully controlled conditions. Laboratory experiments (Figure 8) show that phosphorus uptake by calcium carbonate, under simulated natural conditions, proceeds slowly. The large hydrochloric acid extractable component observed at Rochester may arise from slow uptake and subsequent mineralization of dissolved inorganic phosphorus by carbonate minerals. 

Transformation of reactive organic substances will result in variations of redox potential, pH-values, as well as concentrations of inorganic ions and dissolved organic carbon the latter two components may enhance complexation of metals. Regarding the subsequent consideration, acid-producing potentials derived from oxidation of sulphides and organic matter are of prime importance. 

Red Water — which can be almost black at times - also contains dissolved TNT however, it is not an incidental stream like Pink Water it is a major by-product stream from TNT manuf. The mixed-acid nitration of toluene yields not only 2,4,6-trinitrotoluene, the desired product, but also a host of other isomers and by-products amounting to approx 4.5% of the total yield and it is necessary to remove them from the product. They are removed by extraction with a Na sulfite—Na carbonate soln which sulfonates and dissolves them the extract is called Red Water. Red Water is a very complex and somewhat variable mixt containing 15% or so of sulfonated or sellited nitrobodies and a number of inorganic salts. Typical components are w, NajSOj—NaS04, NaN02— NaNOj, sulfonated or... 

---