FISHERY BULLETIN: \0L. 69, NO. 2 



less than 1-2 /x in diameter, then the experi- 

 mental DDT uptake results that have been in- 

 terpreted in terms of a partition coefficient or 

 a concentration factor using the nominal con- 

 centration of DDT in the aqueous medium be- 

 come relatively meaningless without knowledge 

 of the fraction of the initial amount of DDT 

 present which is fixed to these small particles 

 and hence unavailable to the test organism. In 

 the oceanic environment, it is quite likely that 

 the amounts of "available" DDT residues are 

 exceedingly small. Uptake of DDT by the seston 

 is probably closely coupled with input pulses 

 which would be largely determined by fallout 

 conditions at the surface and seasonal runoflF 

 of DDT residues from land areas. "Available" 

 DDT residues which may rise during these pe- 

 riods will be taken up by plankton. A complete 

 picture of the processes involved in DDT trans- 

 port to the pelagic environment has yet to be 

 drawn and will require further experiinental and 

 analytical work. 



ACKNOWLEDGMENTS 



I thank David Bracher for technical assist- 

 ance. Vance McClure, John MacGregor, and 

 Robin Burnett gave valuable advice in prepara- 

 tion of the manuscript. The work was support- 

 ed by NSF Grant GB 8408, a grant from the 

 State of California Marine Research, Committee, 

 and an NSF predoctoral fellowship. 



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