Chemistry of Shallow Seawater

Near-surface seawater is typically supersaturated by over six times with respect to calcite, and over four times with respect to aragonite (see Chapter 4). When it flows over shallow areas of the world s oceans, its chemistry can be modified by several different processes. The extent of modification is strongly dependent on the residence time of the water over the shallow areas. Morphologic controls on flow, such as embayments, barrier islands, and reefs, can often lead to significant restriction of the flow of seawater. In areas where these restrictions occur, major changes in the chemistry of the seawater are usually observed. 

Other than salinity changes, the major process altering the chemistry of the northern Great Bahama Bank waters is CaC03 production. Because changes in salinity will modify calcium concentrations and alkalinity, it is necessary to 

There are three primary hypotheses for their mode of formation. The first is that they are simply sediment that has been resuspended by bottom feeding fish. The mullet muds in Florida Bay are probably an example of this process. The second is that they result from spontaneous precipitation of CaCC 3 which may be 

The effect of photosynthesis, which would be associated with diatom blooms, on inducing carbonate mineral precipitation is shown in the following reactions  

Major problems concerning whiting formation still exist, not least of which are the distribution and longevity of whitings, their concentrated nature and lack of major water chemistry changes within whiting areas. The conclusions presented here have important implications for the production of fine-grained carbonate particles in modem and ancient depositional environments. Some further aspects of the production of these particles are discussed in the next section. 

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