646 Marine Microbiology 



that calculated from dilution of the effluent. The reason for this 

 deficiency, which reached a maximum after about one hour, is 

 unknown. After one hour, the observed values approached the 

 calculated values at a decreasing rate; the difference is assumed 

 to have been due to mineralization. A similar relationship existed 

 for PO4-P. Table 1 summarizes computations of mineralization 

 rates for nitrogen and phospliorus during the first day; the infor- 

 mation available for the present study required the use of ex- 

 trapolated values as indicated. As a first approximation, organic 

 nitrogen and phosphorus are assumed to have been mineralized 

 in the effluent field at rates of about 2 and 0.6 kg/day, respective- 



The NO.i-N and PO4-P distributions shown in Figure 2 sug- 

 gest that there are two distinct areas of mineralization, one within 

 the effluent field and one at the bottom; similar distributions have 

 been observed near other Southern California outfalls (12). A 

 comparison of median concentrations of NO,-N and PO4-P 

 throughout the water column near Hyperion with background 

 concentrations observed on the same day at a point (AHF Sta 

 3827) about 20 km south of the outfall indicates that at the 7.5 

 m depth, the nitrate and phosphate concentrations were essen- 

 tially normal. In the lower 7.6 m of the water column, NO3-N 

 and PO4-P concentrations averaged about 30 and 20 Mg/L above 

 normal. If it is assumed that these are steady-state values over an 

 average width of 1 km, and that the net flushing cun-ent in this 

 area averages 5 cm/sec, about 1,000 kg nitrogen and 667 kg phos- 

 phorus were released daily to the bottom waters from the sedi- 

 ment. The NO3-N derived from the 20,000 kg of organic nitrogen 

 which settled during the first day. The phosphorus could have 

 come from both the 5,000 kg organic and the 460 kg PO4-P de- 

 posited; accordingly, a lower limit of 200 kg/day from the former 

 is established. An intermediate value of 300 kg/day is adopted for 

 regeneration of phosphorus as being more consistent with the 

 N:P ratio for mineralization in the effluent field. 



Nitrification in the effluent field is suggested in Figure 2. An 

 analysis of crude averages of NH3-N and NO3-N variations during 

 the first four hours of tiavel, made with the same provision for 



