i. Photosynthesis-Respiration 



Photosynthesis 



CO2 + H2O + Nutrients + Energy ^ (1) 



Respiration 



nC(H20)«nutride + O2 



ii. Skeletal Mineral Formation 



Organic Activity + lonicConstituents 



Foraminifera 



Coral Skeletal Material 



■ — > 



Coccoplithophores 



Pteropods [Ca (Mg, Sr, etcOCOa] (2) 



Minor Minerals 



Barite (BaS04) 



Celestite (SrS04) 



Phosphorite (Ca2P04F) 

 iii. Bacterial Activity in Anoxic Water and Sediments 



Bacteria 

 Organic Material + Sulfate + Iron * (3) 



Pyrite + H2S + HS" + S= 



Dissolved inorganic carbon is the only one of the major constituents 

 (as defined) that is directly influenced by photosynthesis and respiration. 

 The decrease in carbon dioxide in surface water caused by photosyn- 

 thesis and the increase in carbon dioxide in intermediate and deep waters 

 caused by respiration are routinely measured as part of many investi- 

 gations and are relatively well understood. 



In skeletal mineral formation, biological activity acts to bring about 

 the formation of minerals that are near saturation in the sea. The reasons 

 for the formation of a specific mineral in preference to another (i.e. 

 high magnesium calcite over argonite, etc.) are not well understood, 

 but may be attributed to the amino acid or other organic makeup of the 

 organisms. Since calcium carbonates are "sinks" for magnesium and 

 strontium as well as for calcium and carbon, a change in the species 

 of carbonate-depositing organisms may result in a change in the relative 

 amounts of magnesium, strontium, and other elements being removed 

 through geologic time. 



Similarly, phosphorites are the result of organic activity in areas of 

 upweUing. Recent evidence (Kolodny and Kaplan, 1970) indicates that 



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