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I have submitted for the record a small paper read to oceanographers 

 and geophysicists last week in Ensenada, Baja California, at a gather- 

 ing of the Mexican Geophysical Union. This may appear strange, but 

 it may help illustrate in the briefest possible time one point I wish to 

 make here today. 



8ome of us are repeatedly asked about changes that may be taking 

 place as a result of ocean disposal of radioactive wastes of various 

 kinds. I have personal interest in changes in radioactivities, even the 

 smallest, in the ocean. However, many of the necessary measurements 

 are difficult to make at present, so it is necessary to enlist all sorts of 

 assistance from general oceanographic knowledge. 



It occurred to me last week that the Ensenada scientists might be 

 interested in some of the indirect methods we have frequently used in 

 establishing whether or not those radioactive nuclides we have found 

 in our local marine environments might be attributed to a nearby 

 nuclear power reactor. 



For several years now we have visited the clean rocky coasts below 

 that Mexican city to collect black sea mussels and other marine orga- 

 nisms as reference samples for making comparisons w'ith samples we 

 collect locally. 



Extreme radiation detection sensitivity often may be realized 

 through use of living tissues. However, it is of utmost importance to 

 choose comparable plants or animals and to collect at comparable 

 seasons. Also one must learn something about the origins of the en- 

 vironmental waters. 



The objective of that paper Avas a demonstration that a comparison 

 between the environment near San Onofre (lying 40 miles north of 

 Scripps) and another environment to be found 100 miles south of the 

 border Avliere water is more truly oceanic, requires taking into con- 

 sideration some lar^e-scale movements of the whole Pacific. 



I pointed out incidentally, that it is sometimes helpful to learn also 

 something about the behavior of certain migrating oceanic fish that 

 have added to our knowledge of the retention of certain pollutants in 

 upper ocean layers. 



Now, the levels of artificial nuclides in the open Pacific are almost 

 entirely due to global fallout that mostly entered years ago. To decide 

 how much of this has come to our coasts we must consult fallout records 

 and oceanographic information about currents, mixing, and eddies. 

 In short, we have to consider several things that happened a long time 

 ago and far away. 



As you will see in that paper, I attempted to summarize as a single 

 final sketch the whole oceanic region that must be reviewed, from 

 Japan to Mexico. However, what fell out was a strong emphasis of the 

 foreground suggesting an exceptionally important part was being 

 played by a more or less permanent cduntercurrent flowing immedi- 

 ately along our southern California coast. Inside of the large south- 

 ward directed California current, this countercurrent frequently 

 flows northward from Baja California, past San Diego, then Los 

 Anegeles Harbor and even sometimes past Santa Barbara. 



This current, of course, is part of a large offshore dynamic eddy ; it 

 is variable, but it is fairly persistent. 



This is a real feature of our local coast and one not unknown to 

 Mexican oceanographers. However, they were not uninterested be- 

 cause they recognized the pleasing possibility of Mexican citizens at 



