Mineralization of Organic Matter in Santa Monica Bay 651 



10"^ ni' within which, increased surface phosphate concentrations 

 were observed. If it is further assumed that the lower and higher 

 rates are associated with the lesser and greater areas, it is possible 

 to compare annual rates of nutrient regeneration with those re- 

 ported for other areas. 



The annual rate of nitrogen mineralization may be computed 

 as 1 X W g/day x 365 days/yr - 1.42 x 10^ m^ = 26 g/mVyr. 

 Essentially all of this regeneration takes place on the bottom and 

 it exceeds, by two orders of magnitude, the value of 1.57 /xg- 

 atoms/cm^/yr (0.22 g/m^yr) reported by Rittenberg et al. (10) 

 for the upper 200 cm of sediment in Santa Barbara Basin where 

 the bottom depth is 600 m. A second comparison may be made 

 with the upper 200 m of the ocean by assuming the annual pro- 

 duction figure of 150 g carbon/m^/year adopted by Emery et al. 

 (2), multiplying by the factor O.lSg N/g C from Sverdiup et al. 

 (14), and accepting Riley's (8) estimate of 90 per cent regenera- 

 tion within that depth; the resulting rate for nitrogen mineraliza- 

 tion is 24 g/m^/yr. 



Phosphorus mineralization may be computed from the profile 

 data as 3 x 10^ g/day x 365 days/yr - 1.42 x 10^ m^ = 7.7 

 g/m^/yr and from the areal data as 3.5 x 10^ g/day x 365 days/yr 

 -^ 1.38 X 10^ m^ = 9.3 g/m^/yr. Regeneration in the ocean may 

 be computed by using the factor, 0.024 g P/g C, after Sverdrup 

 et al. (14) and proceeding as above; this results in 3.2 gP/m^/yr. 



It appears that there is a relative excess of phosphorus 

 regenerated in Santa Monica Bay. This corresponds roughly with 

 the N:P ratio in the dicharge, but it is not known why this im- 

 balance of nutrients should persist through the mineralization 

 processes. 



SUMMARY 



An investigation has been made of the rates of mineralization 

 of the 22,000 kg and the 5,500 kg organic nitrogen and phosphorus 

 discharged daily with the effluent from the Hyperion Sewage 

 Treatment Plant into Santa Monica Bay in 1956. Regeneration 

 rates of 1,000 kg per day for nitrogen and from 300 to 3,500 kg 

 per day for phosphorus have been computed; on an areal basis, 

 these amount to 26 g N/m^/yr and 7.7 to 9.3 g P/m^/yr since 

 di£Ferent areas were involved. Most of the regeneration took 



