MacGREGOR: DDT OFF SOUTHERN CALIFORNIA 



and 890 m deep, and 5 to 11 nautical miles from 

 the sewer outfalls. Total DDT remained low in 

 these stations averaging about 30 mg/m^ of 

 bottom, and the composition was essentially 

 unchanged. 



The remaining three stations, in areas of much 

 higher pollution within 1.3 nautical miles of the 

 sewer outfalls and in shallower water, showed 

 some apparent changes in grams per square 

 meter of bottom (Table 4). 



Table 4. — Changes in composition (in grams per square meter 

 of bottom) at stations 42-21, 43-21, and 42-19 in 11 mo. 



At station 42-21, DDT, DDD, andp,p'DDE re- 

 mained relatively unchanged with a total of 

 4.2 g/m^ of bottom in both years, while the 

 o,p'DDE-DDMU peak increased by almost four 

 times. At the two shallower stations, 43-21 and 

 42-19, DDT, DDD, and p,p'DDE decreased in 

 1972 to less than half its value in 1971, while the 

 o,p'DDE-DDMU peak more than doubled. These 

 changes could be caused by metabolism, by the 

 addition of sewage deposits that were relatively 

 free of DDT combined with metabolism, or even 

 by the removal of a few centimeters of the 

 deposits in the shallow-water areas without 

 metabolism. 



CONCLUSIONS 



Total DDT in the bottom sediments in the 

 ocean off southern California in an area of 911 sq 

 nautical miles was estimated to be between 200 

 and 300 metric tons. Most of the total DDT 

 was concentrated in a relatively small area with- 



in a few miles of the Los Angeles County sewer 

 outfalls. 



Total DDT in the top 10 cm of sediment ranged 

 from 6,600 mg/m^ of bottom near the sewer out- 

 falls to about 1 mg/m^ of bottom at the more dis- 

 tant stations. 



Eighty-two percent of the total DDT was DDE; 

 10%, DDD; and 8%, DDT. Metabolism of DDT to 

 DDD and DDE was more rapid in shallow waters 

 and apparently very slow or lacking in deep, 

 cold waters that were low in oxygen. Seven 

 samples taken 11 mo later tended to confirm 

 these findings. 



ACKNOWLEDGMENTS 



I am indebted to W. Rommel, G. Boehlert, and 

 V. McClure for their advice and help in process- 

 ing the samples; to G. Stauffer for programming 

 the data for the computer; to R. Lasker for valu- 

 able criticism and guidance; to the personnel of 

 the RV David Starr Jordan for their cooperation, 

 assistance, and interest; and to K. Raymond for 

 preparing the figures. This work was supported in 

 part by NOAA, Office of Sea Grant, under grant 

 #UCSD 2-35208 with the Institute of Marine Re- 

 sources, University of California. 



LITERATURE CITED 



MacGregor, J. S. 



1974. Changes in the amount and proportions of DDT 

 and its metaboHtes, DDE and DDD, in the marine en- 

 vironment off southern California, 1949-72. Fish. Bull., 

 U.S. 72:275-293. 

 McCLURE, V. E. 



1972. Precisely deactivated adsorbents applied to the 

 separation of chlorinated hydrocarbons. J. Chro- 

 matogr. 70:168-170. 

 MCDERMOTT, D. J., AND T. C. HEESEN. 



1974. Inventory of DDT in sediments. Annual report for 

 the year ended 30 June 1974. Southern California 

 Coastal Water Research Project, p. 123-127. 

 MCDERMOTT, D. J., T. C. HEESEN, AND D. R. YOUNG. 



1974. DDT in bottom sediments around five southern 

 California outfall systems. TM 217. Southern California 

 Coastal Water Research Project, 54 p. 

 NATIONAL ACADEMY OF SCIENCES. 



1971. Chlorinated hydrocarbons in the marine environ- 

 ment. Wash., D.C., 42 p. 



WooDWELL, G. M., P. P. Craig, and H. A. Johnson. 



1971. DDT in the biosphere: Where does it go? Science 

 (Wash., D.C.) 174:1101-1107. 



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