89 



the environment under which the sediment was deposited and 

 the type of plants and animals from which it was derived. 

 Furthermore, sediments containing appreciable quantities of 

 sewage may require an entirely different factor than those 

 given above. For these reasons, the per cent organic carbon 

 is used in this report to discuss the relative amounts of 

 organic matter, and these values must be multiplied by some 

 factor (such as the above) if the total quantity is desired. 

 Source of Organic Matter . The source of organic debris 

 in the ocean is both the land and sea. However, since the 

 amount of organic matter brought to Santa Monica Bay by 

 streams is negligible, it can be neglected. An important 

 local source is the sewage discharged into the bay, but the 

 most important source is phytoplankton which is the basic 

 nourishment of all life in the ocean. Only a small portion 

 of the organic material from the water survives the fall 

 through the water or escapes consumption on the bottom by 

 scavangers or oxidation. Sverdrup, et al_„ (1942, p. 929, 

 938) estimate that between 495 and 990 grams (dry weight) 

 per square meter per year of organic production takes place 

 in the waters off southern California. Emery and Rittenberg 

 (1952) estimate that less than l/l6 of the organic matter 

 produced at the surface of the sea escapes destruction during 

 its travel to the bottom of the basins off southern California. 

 Trask (1939) suggests that only 27o, or 20 grams per square 

 meter per year of organic matter is deposited annually of aji 

 original 1,000 grams produced near the surface of the sea, 

 and that under natural conditions sediments that have been 



