268 



Sediments 



meters in the sediment, Santa Monica be- 

 cause its sediments vary from slightly aerobic 

 to slightly anaerobic with no hydrogen sul- 

 fide, and Santa Barbara because it is anaer- 

 obic with a strong odor of hydrogen sulfide 

 from the surface to the bottom of cores. 



The first product of oxidation of the ni- 

 trogenous portion of organic matter, am- 

 monia, was found in the interstitial waters 

 of the sediments in all three basins. It is 

 most abundant in Santa Barbara and least 

 so in Santa Catalina Basin and increases 

 with depth except for irregularities resulting 

 largely from depth changes in grain size of 

 the enclosing sediment (Fig. 217). Concen- 

 trations reach a maximum of 11,400 ^ug- 



atoms/liters. The next stage of oxidation, 

 nitrite, is well exhibited in sediments of 

 Santa Catalina Basin with concentrations as 

 great as 6jUg-atoms/liter in the aerobic zone 

 but none below. It was found in only the 

 topmost sample of the core from Santa 

 Monica Basin, and only doubtful traces 

 were noted at Santa Barbara Basin. Even 

 in Santa Catalina Basin nitrite is too minor 

 to be shown in Figure 217, probably be- 

 cause it is a transitory intermediate com- 

 pound. The next stage of oxidation, nitrate, 

 is much more abundant in sediments of 

 Santa Catalina than in those of the other 

 basins, reaching a value of 240 |Lig-atoms/ 

 liter at the top of the core and markedly 



100 1000 10,000 



CUMULATIVE ^g NITROGE N /C5R AM 



OF DRY SEDIMENT 



Figure 217. Depth distribution 

 of nitrogen compounds in sed- 

 iments and overlying water of 

 three basins. Note the use of 

 logarithmic scale of concentra- 

 tion. From Rittenberg, Emery, 

 and Orr (1955, Fig. 4). 



