Production of Calcium Carbonate

Tsutsumi, A., Nieh, J.Y. and Fan, L.S., 1991. Role of the bubble wake in fine particle production of calcium carbonate in bubble column systems. Industrial and Engineering Chemistry Research, 30, 2328-2333. 

Zondervan, I. 2007. The effects of light, macronutrients, trace metals and C02 on the production of calcium carbonate and organic carbon in coccolithophores—A review. Deep-Sea Research II, 54, 521-537. 

A topic of considerable controversy is the question of carbonate incorporation in the apatite lattice since carbonate apatite does not precipitate from aqueous solutions28, 395 398 Carbonate apatites (phosphorites) forming in marine environments134 are considered metasomatic alteration products of calcium carbonate, and as a result carbonate content decreases and phosphate content increases with time399. In biophosphates, the situation appears to be just reversed in that carbonate content increases with bone maturation and it was argued that the similarity between bone mineral and naturally occuring C03-apatite ends before it begins 397. ... 

The process of removal of calcium by marine organisms in the water column is well known. Production of calcium carbonate by water column biological processes may be estimated from primary productivity and from the mean chemical composition of plankton. After death of the organisms and removal of the organic protective layer, the skeletons may undergo dissolution if they encounter water undersaturated with respect to their mineral composition. Active dissolution of calcium carbonate occurs mainly near the sediment-water interface in deep waters that are undersaturated with respect to both calcite and aragonite (see Chapter 4). Thus, calcium is regenerated from calcareous skeletons and, finally, only a small fraction of the initial production of these materials accumulates in sediments. An... 

At this point the concentration of both Ca++ and C03 ions is so small (both close to the value 0.00013) that for practical purposes it is disregarded and the filtered solution is said to be free of either calcium or carbonate. However, with so small a Ca++ ion concentration the OH- ion concentration can be quite large without exceeding the solubility product of Ca(OH)2. In fact the filtered solution has a concentration of nearly 2-molal in NaOH. If, however, the OH- ion concentration gets above 2-molal, the Ca++ ion concentration is depressed to such an extent that an appreciable concentration of C03" ions can remain without exceeding the solubility product of calcium carbonate. In other words, if we started with a more concentrated solution of Na2C03 than 10 per cent, a complete conversion to the hydroxide would not be possible. 

The accumulation of calcium carbonate in deep ocean sediments is a complex process. It is primarily governed by the interplay between biological production of calcium carbonate in the nearsurface ocean and the chemistry of deep ocean waters. After over 100 years of study, the major problem of determining the saturation state of deep ocean water remains largely unresolved. It is currently possible, using recent laboratory measurements, to arrive at saturation states that differ by as much as a factor of 2. Both laboratory and water column experiments indicate that calcium carbonate dissolution kinetics are not simply related to saturation state. It is our opinion that the saturation state problem must be resolved and considerably more detail added to our present knowledge of calcium carbonate dissolution kinetics and accumulation patterns before attempts to model the accumulation of calcium carbonate in deep ocean sediments can be truly successful. 

Two further points merit brief attention. If conditions in Table 2.5.12 approximate to the yearly norm, then a windward reef flat of about 400 m width would represent the equilibrium situation on which the production of calcium carbonate would exactly balance the amount lost. Most windward reef flats in fact vary in width between 100—400 m. 

As was mentioned before, several crystalline forms can be produced. These forms are used to build minerals and rocks. These are defined below. There are three crystalline forms which are mostly used in production of calcium carbonate filler ... 

In general, there is relatively little data available on the relative contributions made by different planktonic calcifying organisms (i.e. coccolithophores, foraminifera, pteropods) to the global production of calcium carbonate. Estimates of the coccoUth contribution to pelagic marine carbonate... 

Present-day production of calcium carbonate in the pelagic ocean is calculated to be in the order of 6 to 9 billion tons (bt) per year (60-90-10 mol yr ), from which about 1.1 to 2 bt (11 to 20-10 mol yr ) accumulate in sediments (Tables 9.1 and 9.6). Together with the accumulation in shallow waters of... 

For the calculation of pHg it is possible to derive the following equation from the equation for the second dissociation constant of carbonic acid K2 and the solubility product of calcium carbonate, K ... 

---