46 



KEDFIELD, KETCHUM AND RICHARDS 



[CHAP. 2 



decomposed organic matter liberates phosphorus and carbon in the ratio of 1 

 to 106, the expected ratios of the simultaneous changes in the several com- 

 ponents during each step may be estimated from these equations to be as shown 

 in Table VII. 



Table VII 



Ratio of Change in the Atomic Concentration of Products of Decomposition 

 of Organic Matter in the Presence of Oxygen and Under Anoxic Conditions 



By employing these ratios, the changes in concentration of the products of 

 decomposition during the successive stages may be computed and the results 

 shown as a function of the increasing phosphate phosphorus concentrations, 

 as in Fig. 8. It is necessary to know only the initial concentration of oxygen in 

 the water to obtain quantitative values applicable to any natural situation. 

 Such diagrams are not very exact in respect to the products of denitrification 

 because the separate stages probably overlap, and the completeness of the re- 

 actions involving these fractions is not understood. The presence of nitrite as 



3 4 5 6 7 8 



ZIP (mg atoms/m 3 ) 



Fig. 8. Simultaneous changes in concentration of products of decomposition of organic 

 matter under oxic and anoxic conditions. Calculated assuming initial oxygen content 

 of 615 mg atoms/m 3 , appropriate to surface water of Black Sea. 



