Carbonate in rivers

Various other workers have discussed the determination of organic carbon in river sediments. [18, 23, 24] Suzuki et al. [23] applied wet combustion to the sediment and absorbed the carbon dioxide produced in sodium hydroxide solution, prior to determination in a TOC analyser. Whitfield and McKinley [24] recommended that samples for determination of organic carbon should be filtered immediately and analysed as soon as possible. Charles and Simmons [18] stated that greater accuracy is obtained with dry microcombustion techniques and that wet oxidations with potassium... 

Hope, D., M. F. Billett, and M. S. Cresser. 1994. A review of the export of carbon in river water Fluxes and processes. Environmental Pollution 84 301—324. 

FIGURE 1 Major classes of organic carbon in river water. Monomeric-C is represented by black shading within the histograms. Modified with permission from E. M. Thurmen. 1985. Organic Geochemistry of Natural Waters. Kluwer Academic Publishers Group. 

Spitzy, A. and J. Leenheer. 1991. Dissolved organic carbon in rivers. In Biogeochemistry of Major World Rivers (E. T. Degens, S. Kempe, and J. E. Richey, Eds.), pp. 213-232, Wiley, Chichester, UK. 

Calcification and deposition of carbonates in rivers are uncommon but may be found in some stagnant parts, and in the upper reaches, when the deposits may occur as calcareous tufas, travertines, and sinters (Golubic, 1967,1973). In some rivers, oncoids and algal balls are formed. 

Their contribution to the total dissolved load in rivers can be estimated by considering the mean composition of river water and the relative importance of various rocks to weathering. Estimates (18) indicate that evaporites and carbonates contribute approximately 17% and 38%, respectively, of the total dissolved load in the wodd s rivers. The remaining 45% is the result of the weathering of siUcates, underlining the significant role of these minerals in the overall chemical denudation of the earth s surface. 

Straight-chain detergents don t work in hard water. Phosphates were added to detergents to soften the water, but phosphates are excellent fertilizer for algae in rivers and oceans. The algae blooms deplete the oxygen in the water, which in turn kills fish. Phosphates were replaced with other water softeners such as sodium carbonate and EDTA. 

The results for all sites are given in Table 5.1, and are best considered by dividing sites into three groups according to isotopic nature of the matrix (i) sites with most isotopically emiched matrix carbonates (Die Kelders and Swartkrans), (ii) sites with rather less enriched carbonates (Klasies River Mouth and Makapansgat), and finally (iii) a site with depleted deposit values (Border Cave). This is summarized in Fig. 5.5. The division also fortuitously provides a range of age depths in two categories. As indicated in Table 5.1, many of these data have been published elsewhere, but the purpose for which they are considered in combination here has not been previously attempted. 

There are a large number of literature references that refer the use of SPE cartridges for the extraction of pesticides from water. There are several comprehensive reviews of the use of SPE, including that by Soriano et al. who discussed the advantages and limitations of a number of sorbents for the analysis of carbamates. Hennion reviewed the properties and uses of carbon based materials for extraction of a wide multiclass range of pesticides. Thorstensen et al. described the use of a high-capacity cross-linked polystyrene-based polymer for the SPE of phenoxy acids and bentazone, and Tanabe et al reported the use of a styrene-divinylbenzene copolymer for the determination of 90 pesticides and related compounds in river water. SPE cartridges are also widely used for the cleanup of solvent extracts, as described below. 

Presently, the precise determination of the true dissolved Th fraction in water samples remains a challenge. Results from ultrafiltration experiments on organic-rich water samples from the Mengong river tend to demonstrate that Th concentration is less than 15 ng/L in absence of DOC (Table 2 and Viers et al. 1997), and that Th is still controlled by organic carbon in the final filtrate of the ultrafiltration experiments. The latter conclusion is also supported by the results obtained for the Kalix river (Porcelli et al. 2001). These results therefore not only raised the question of the determination of the amount of dissolved Th in water but also of the nature of Th chemical speciation. 

Tipper ET, Bickle MJ, Galy A, West AJ, PomiFs C, Chapman HJ (2006) The short term climatic sensitivity of carbonate and silicate weathering fluxes insight from seasonal variations in river chemistry. Geochim Cosmochim Acta 70(ll) 2737-2754... 

If 0.24 Pg C/a represents riverine DIC delivered to oceans (Meybeck 1993) and if the flux of carbon from rivers/lakes to the atmosphere is 20% (Kling et al. 1991) of the total (i.e., 0.12 Pg C/a), then 0.23 Pg C/a remains in inland lakes and rivers, and in slowly cycled groundwater. Cole et al. (2007) estimated that about 0.2 Pg C/a is buried in inland water sediments. Groundwater may have a greater carbon storage capacity due to its large volume and greater load of carbon than rivers (Kempe 1984). 

Petroleum is formed under the earth s surface by the decomposition of organic material. The remains of tiny organisms that lived in the sea and, to a lesser extent, those of land organisms were carried down to the sea in rivers along with plants that grow on the ocean bottoms combined with the fine sands and silts in calm sea basins. These deposits, which are rich in organic materials, become the source rocks for the formation of carbon and hydrogen, i.e., natural gas and crude oil. 

Whitfield and McKinley [24] studied some of the factors affecting the determination of particulate carbon and nitrogen in river water sediments. 

Postma D (1977) The occurrence and chemical composition of recent Ee-rich mixed carbonates in a river bog. JSed Pet 47 1089-1098... 

Because sulfuric acid is a strong acid, it is a more potent weathering agent than carbonic acid. By serving as a source of H (aq), sulfuric acid is transformed into SO Caq). The oxidation of pyrite is responsible for 11% of the sulfete in river water, with pollution now contributing 54%. The latter is largely associated with the burning of sulfur-rich coal. 

Considerable geographic variability exists in the distribution of the source rocks contributing salts to river and groundwaters. As shown in Table 21.3, most of the evaporites, which are the dominant natural source of Na and Cl in river water, lie in marginal and endorheic (internal) seas. Some of these subsurfece evaporite deposits dissolve into groundwaters, which eventually carry Na and Cl into the ocean. Carbonates are the prevalent rock type between 15°N and 65°N. Precambrian-age crustal rocks and meta-morphic minerals predominate between 25°S and 15°N and north of 55°N. Shales and sandstones represent on average 16% of the terrestrial surfece lithology. 

Fig. 3.23 Carbon isotopic composition of total dissolved carbon in some large river systems. Data source Amazon LongineUi and Edmond (1983), Rhine Buhl et al. (1991), St Lawrence Yang et al. (1996)...

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