DDT AND ITS METABOLITES IN THE SEDIMENTS 

 OFF SOUTHERN CALIFORNIA 



John S. MacGregori 



ABSTRACT 



To assess the degree of DDT contamination in the marine sediments off Los Angeles, 103 stations in 

 the Pacific Ocean off southern Cahfomia were sampled in July and August 1971 for DDT and its 

 metabolites, DDD and DDE. Heavy contamination of bottom sediments in this area was expected 

 because of large amounts of DDT that have entered the ocean through the Los Angeles County sewer 

 system as waste from a DDT manufacturing plant. 



From the data acquired, it was estimated that there were about 200 metric tons of DDT, DDD, and 

 DDE in the sediments in an area of 14 square nautical miles near the sewer outfalls and 300 metric 

 tons in the entire 911 square nautical mile area sampled. The heaviest concentrations of total DDT 

 were distributed in the relatively shallow- water area on the Palos Verdes shelf to the northwest of the 

 sewer outfalls in the general direction of the current flow. 



Metabolism of DDT was inhibited in deepwater sediments. Ratios of DDE to DDT were low, and 

 DDT was more abundant than DDE at some stations. In sediments from shallow- water stations, DDE 

 exceeded DDT by more than 10 times. 



The bottom of the ocean off Los Angeles, CaHf, 

 has been very heavily contaminated with the 

 pesticide DDT owing to the discharge of wastes 

 from a DDT manufacturing plant into the Los 

 Angeles County sewer system over a period of 

 about 20 yr ending in 1970 (MacGregor 1974). 



The amount of DDT which entered the ocean 

 through the Los Angeles County sewer system 

 was estimated at 250 kg/day. Following the ces- 

 sation of DDT discharges by the manufacturer, 

 the amount entering the ocean dropped to 45 

 kg/day in December 1970 and to 11 kg/day in 

 October 1971. Most of these later discharges re- 

 sulted from sewer cleaning operations which 

 stirred up old deposits of DDT in the sewer lines. 

 The discharges resulting from the cleaning oper- 

 ations were primarily DDD and DDE, metabo- 

 lites of DDT, while the earlier discharges were 

 primarily DDT. 



Because there has been a great deal of specula- 

 tion about the fate of DDT and other toxic chem- 

 icals released into the environment by man 

 (Woodwell et. al. 1971; National Academy of 

 Sciences 1971), this investigation was under- 

 taken to determine the areal distribution and 

 fate of these chemicals in the bottom sediments 

 in the ocean off Los Angeles. 



^Southwest Fisheries Center, La Jolla Laboratory, National 

 Marine Fisheries Service, NOAA, La Jolla, CA 92038. 



MATERIALS AND METHODS 



The bottom sediments were sampled from a 

 grid of 103 stations between lat. 33°30' and 

 33°58'N and long. 118°00' and 118°44'W (Figure 

 1). The stations were designated by four-digit 

 numbers, the first two indicating minutes north 



Manuscript accepted June 1975. 



FISHERY BULLETIN: VOL. 74, NO. 1, 1976. 



Figure l. — Distribution of total DDT in milligrams per square 

 meter of bottom in the sediments of southern California. Total 

 DDT ranged from 6,600 mg/m^ of bottom at station 43-22 to 

 0.12 mg/m^ at station 30-08. 



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