Calcium carbonate saturation

Sa.tura.tion Index. Materials of constmction used in pools are subject to the corrosive effects of water, eg, iron and copper equipment can corrode whereas concrete and plaster can undergo dissolution, ie, etching. The corrosion rate of metallic surfaces has been shown to be a function of the concentrations of Cl ,, dissolved O2, alkalinity, and Ca hardness as well as buffer intensity, time, and the calcium carbonate saturation index (35). 

Larson, T.E. and Buswell, A.M., Calcium carbonation saturation index and alkalinity interpretations, J. Am. Water Works Assoc., 34, 1667-1684, 1942. 

Langdon, C., Takahashi, T., Sweeney, C., Chipman, D., Goddard, J., Marubini, F., Aceves, H., Barnett, H., and Atkinson, M.J., Effect of calcium carbonate saturation state on the calcification rate of an experimental coral reef, Global Biogeochem. Cy., 14, 639-654,2000. 

This is no real surprise since the first four equations were assumed to be obeyed. Only the last condition of calcium carbonate saturation is grossly violated. The first increment is obtained in the usual way as —D lf and gives... 

The scale formed under moderate temperatures is usually due to temporary (bicarbonate) hardness being converted into calcium carbonate, which occurs on heating or increase in alkalinity sufficient to result in calcium carbonate saturation. The solubility of calcium carbonate also affects corrosion since the alkalinity of dissolved carbon dioxide in the water is greatly reduced as the saturation equilibrium is approached. Ideally, at equilibrium the various forms of carbon dioxide (free C02, bicarbonate and carbonate) are so balanced that they cause neither scale nor corrosion. 

The effects of pressure on equilibria in the oceans within depth profiles have been studied mostly in relation to the problem of calcium carbonate saturation in this environment (Millero, 1969 Bemer, 1965 Millero and Bemer, 1972 Edmond and Gieskes, 1970). The early calculations by Owen and Brinkley (1941) concerning the effect of pressure upon ionic equilibria in salt solutions have been extended to studies of BaS04 solubility at different depths (Chow and Goldberg, 1960) and to the pressure dependence of sulfate associations (Fisher, 1972). 

Sample Calculation of Calcium Carbonate Saturation State in Seawater (After Morse et al. (35))... 

The Distribution of Calcium Carbonate Saturation States and Their Relation to Sediment Marker Levels... 

Temperature. Water temperature is an important parameter in calculations of oxygen solubility, calcium carbonate saturation and stabiUty, and various forms of alkalinity, as well as in determining basic hydrobiological characteristics. The temperature should be taken in situ for accuracy, and a standard mercury thermometer with readings to the nearest 0.1°C should be used. It should be calibrated against a precision thermometer certified by the National Bureau of Standards. A thermistor is preferable when attempting to measure temperature at different depths and for automated monitoring and surveillance, and should be similady calibrated (see TemperaTUREMEASUREMENT). 

Chave, K.E. and Suess, E., 1970. Calcium carbonate saturation in seawater Effects of dissolved organic matter. Limnol. Oceanogr., 15 633—637. 

Cements from meteoric waters may develop in beachrock during precipitation from percolating calcium-carbonate-saturated rain water during low... 

Calcium Carbonate saturated H ".. firtrtMit.. DuPont Can. Sclafr... 

Only phosphate mineral formation will be considered here. Sulfide equilibria are discussed in detail in Part II and calcium-carbonate saturation states will be considered in another paper (or see Aller, 1977). NH4" is unlikely to be involved in the formation of specific insoluble phases such as struvite (MgNH4P04 6H2O), given the measured concentrations of the ions involved (Martens et al., 1978). The major interactions of with sedimentary particles include reversible and irreversible adsorption reactions (Nommik, 1%5 Mortland and Wolcott, 1%5 Muller, 1977 Rosenfeld, 1979). 

At equilibrium, the rate of carbonate dissolution is equal to the rate of its precipitation and the sea water is said to be saturated with respect to the carbonate phase. In the deep sea, the degree of calcium carbonate saturation (D) can be expressed as ... 

Source Fiom T. E, Lcnson and A. M. Buswell, "Calcium Carbonate Saturation Index and Alkalinity Interprelotions," Am. Wafer Works Assoc., 34 1664 (1942). 

This reaction depends on the calcium carbonate saturation state Q the latter is... 

If the water to be analyzed lies in the range of the so-called lime/carbonic acid equilibrium, i.e. approximately in the range of calcium carbonate saturation, the difference in pH before and after adding calcium carbonate is smaller than 0.04. 

Dilute seawater is undersaturated in carbonates, which reduces the likelihood of forming protective ctdcareous films on a metal surface. In deep ocean waters, the calcareous deposits are not spontaneously formed in an ambient environment and are often not precipitated under cathodic protection conditions [6]. In the cold waters of the deep ocean environmental zones, the precipitation and/or dissolution of the calcareous deposits is mainly controlled by the calcium carbonate saturation level, II [25]. 

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