Carbonate in seawater

Guo LD, Santschi PH (1996) A critical evaluation of the cross-flow ultrafiltration technique for sampling colloidal organic carbon in seawater. Marine Chem 55 113-127 Guo LD, Wen LS, Tang DG, Santschi PH (2000) Re-examination of cross-flow ultrafiltration for sampling aquatic colloids evidence from molecular probes. Marine Chem 69 75-90 Guo LD, Hunt BJ, Santschi PH (2001) Ultrafiltration behavior of major ions (Na, Ca, Mg, F, Cl, and SO4) in natnral waters. Water Res 35 1500-1508... 

In the shore laboratory, the samples must be handled with the care needed for any trace analysis. It must be remembered that the total amount of organic carbon in seawater is around 1 ppm single compounds are likely to be present at ppb levels. In order to collect enough material even for positive identification of some of the compounds present, the materials must often be concentrated. 

A computer program has been used to calculate the magnitude of systematic errors incurred in the evaluation of equivalence points in hydrochloric acid titrations of total alkalinity and carbonate in seawater by means of Gran plots. Hansson [13] devised a modification of the Gran procedure that gives improved accuracy and precision. The procedure requires approximate knowledge of all stability constants in the titration. 

Simply on the basis of the normal composition of marine organisms, we would expect proteins and peptides to be normal constituents of the dissolved organic carbon in seawater. While free amino acids might be expected as products of enzymic hydrolysis of proteins, the rapid uptake of these compounds by bacteria would lead us to expect that free amino acids would normally constitute a minor part of the dissolved organic pool. This is precisely what we do find the concentration of free amino acids seldom exceeds 150 xg/l in the open ocean. It would be expected that the concentration of combined amino acids would be many times as great. There have been relatively few measurements of proteins and peptides, and most of the measurements were obtained by measuring the free amino acids before and after a hydrolysis step. Representative methods of this type have been described [245-259]. Since these methods are basically free amino acid methods, they will be discussed next in conjunction with those methods. 

MacKinnon MD (1977) The analysis of the total organic carbon in seawater a. Development of methods for the quantification of TOC b. Measurement and examination of the volatile fraction of the TOC. PhD Dissertation. Dalhousie University... 

The quantity of dissolved organic carbon in the oceans has been estimated to be about 1018 g and constitutes one of the major reservoirs of organic carbon. Although large in total mass, the concentration of organic carbon in seawater is low (typically 0.5 -1.5 mg C per litre). 

Because they are so intimately related, for the purposes of this discussion, the categories of total and dissolved organic carbon are combined in this section. Also it is doubtful in any case that anyone ever measures a true total organic carbon in seawater. The total organic carbon should include... 

In this connection, Gershey et al. [ 58 ], in a detailed study, have compared results obtained for dissolved organic carbon in seawater using the evaporation-... 

Stoll et al. [142] have described a rapid continuous-flow determination of total inorganic carbon in seawater samples. The method runs on an autoanalyser Traacs 800 spectrophotometric system and is calibrated versus certified reference materials readily available. A typical analysis speed of 45 samples per hour can be reached with an accuracy of 2-3 xM and a precision of 2.5 xM. 

In further work to that discussed above, MacKinnon [183] has discussed in detail a method for the measurement of the volatile fraction of total organic carbon in seawater. 

Wangersky PJ (1975) Measurement of organic carbon in seawater. In Analytical Methods in Oceanography (ed Gibb TRP) American Chemical Society Washington DC, p 148-162... 

The rock in question might contain a large amount of calcite cement, but the reaction path predicts that only a trace of calcite forms during burial. Considering this contradiction, the modeler realizes that this model could not have been successful in the first place there is not enough calcium or carbonate in seawater to have formed that amount of cement. The model in this case was improperly conceptualized as a closed rather than open system. 

Berner, R.A. Morse, J.M. 1974. Dissolution kinetics of calcium carbonate in seawater. IV. Theory of calcite dissolution, American Journal of Science, 274,108-134. 

Gershey, R.M., M.D. MacKinnon, P.J. leB Williams, and R.M. Moore. 1979. Comparison of three oxidation methods used for the analysis of the dissolved organic carbon in seawater. Marine Chemistry 7 289-306. 

MacKinnon, M.D. 1981. The measurement of organic carbon in seawater. Pp.415-443 in Marine Organic Chemistry, E.K. Duursma and R. Dawson, eds., New York Elsevier. 

Sharp, J.H., R. Benner, L. Bennett, C.A. Carlson, S.E. Fitzwater, E.T. Peltzer, and L.M. Tupas. 1995. Analyses of dissolved organic carbon in seawater The JGOFS EQPAC methods... 

Sugimura, Y., and Y. Suzuki. 1988. A high temperature catalytic oxidation method for the determination of non-volatile dissolved organic carbon in seawater by direct injection of a liquid sample. Marine Chemistry 41 105-131. 

Only 10% of the dissolved organic carbon in seawater has been characterized on a molecular level. About 5 to 23% of this DOC can be isolated from seawater by adsorption onto a nonionic macroporous resin fiallowed by elution with an alkaline solution. 

A method to measure soluble organic carbon in seawater includes oxidation of the organic materials to C02 with K2S2Og, followed by gravimetric determination of the C02 trapped by a column of NaOH-coated asbestos. A water sample weighing 6.234 g produced 2.378 mg of CO, (FM 44.010). Calculate the ppm carbon in the seawater. 

Menzel, D. W., and Vaccaro, R. F. (1964) The measurement of dissolved organic and particulate carbon in seawater. Limnol. Oceanogr. 9,138-142. 

Sharp, J. H. (1973) Total organic carbon in seawater—Comparison of measurements using persulfate oxidation and high temperature combustion. Mar. Chem. 1, 211-229. 

An approach such as that suggested for the re-examination of the molecular weight distribution of dissolved organic carbon in seawater (Carlson et al., 1985) has been successfully adapted to evaluate the performance of ultrafiltration in the study of radionuclide speciation ... 

Wang, J.T., Z.B. Zhang, and L.S. Liu. 1997. Determination of dissolved organic carbon in seawater using UV/persulphate method and HTCO method. Chin. J. Oceanol. Limnol. 15 25-31. 

Song, J., X. Li, N. Li, X. Gao, H. Yuan, and T. Zhan. 2004. Simple and accurate method for determining accurately dissolved inorganic carbon in seawaters. Fenxi Huaxue 32 1689-1692. 

Figure 7.6. Relative dissolution rates of biogenic carbonates in seawater undersaturated with respect to calcite. (After Walter, 1985.)...

Keir R.S. (1980) The dissolution kinetics of biogenic calcium carbonates in seawater. Geochim. Cosmochim. Acta 44, 241-252. 

Morse J.W. (1978) Dissolution kinetics of calcium carbonate in seawater. VI The near-equilibrium dissolution kinetics of calcium carbonate-rich deep sea sediments. Amer. J. Sci. 278, 344-355. 

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