8 



nutrients rise to the surface with the effluent column and 

 then spread and diffuse into the surrounding sea water. The 

 silicate and nitrate persist for greater distances and through 

 a much greater thickness of water than around the other out- 

 falls. But even these approach normal shelf values within 

 9,000 feet of the outfall area under most conditions. From 

 the nutrient profiles there is little indication of sedi- 

 mentation, so it appears reasonable to assume that here, at 

 least, the available nutrients are concentrated in the fluid 

 portion of the effluent and not with the particulate matter. 

 The oxygen profile is a better indication of sedimentation, 

 showing an upper and lower layer of relatively low oxygen 

 which meet at an average distance of 2,700 feet. The lower 

 values are probably due to the oxygen demand of the parti- 

 culate matter discharged and thus indicate to a certain 

 extent the sedimentation profile of the debris. 



On December 19 and 20 there was a fairly uniform and 

 recognizable distribution pattern of nutrient salts (Figures 

 2 and 3). Differences existed each day, however, with respect 

 to concentration, location, and extent of the nutrient fields. 



The silicate on December 19 was most concentrated approxi- 

 mately 2,000 feet west of the boil. On December 20 the area 

 of concentration was about 500 feet east of the boil, and the 

 movement of the field (due to changing wind direction) is 

 considered responsible for this shift. Concentrations were 

 more than double on December 20, and field of dispersion was 

 considerably larger than on the 19tho Also on 20th, a silicate- 

 silicon concentration of 10 /'g-a/L or more extended over a 



