PART X — ENVIRONMENTAL CONTAMINANTS 



paint, and components of caulking 

 materials. They probably behave 

 similarly to the halogenated hydro- 

 carbons in organisms, and there is 

 great concern over their buildup in 

 the marine environment. (See Figure 

 X-16) Such materials will receive a 

 good deal of attention in the coming 

 years. But of greater importance will 

 be the identification of other chemi- 

 cals that are building up in organisms 

 of the sea and that are capable of 

 altering their life processes. 



Deleterious effects due to the entry 

 of man's artifacts to the atmosphere- 

 ocean system have been documented 

 in only a few cases, such as those of 

 pesticide residues on the reproductive 

 success of some marine birds. We 

 can expect other catastrophic episodes 

 in the future, however. To react 

 rationally and effectively to such 

 events and to minimize their recur- 

 rences, it will be important to have a 

 past record of man's inputs to his 

 environment, especially of substances 

 that we do not now monitor for one 

 reason or another. 



Use of Glaciers in 

 Atmospheric Monitoring 



The idea of utilizing permanent 

 snowfields (glaciers) to provide such 

 information is not new. Yet researches 

 on the glacial records of man's activi- 

 ties at the earth's surface have so far 

 been small and limited, even though 

 permanent snowfields exist below all 

 of the major wind systems and main- 

 tain sequential records of atmospheric 

 fallout for centuries and even for mil- 

 lenia. Work on lead concentrations 

 in ice layers from northern Greenland 

 and from the interior of Antarctica 

 have shown increases beginning at 

 800 b.c. to the present, with the 

 sharpest rise occurring after 1940. 



These increases are ascribed mainly 

 to lead smelteries before 1940 and 

 to burned lead tetra-ethyl and lead 

 tetra-methyl in internal combustion 

 engines after 1940. In both cases, 

 lead was introduced to the atmos- 

 phere and brought back to the surface 

 of the earth primarily in precipitation. 



The surface sea waters today show 

 much higher lead concentrations than 

 their deeper counterparts, an effect 

 that diminishes as the open ocean is 

 is approached. Predictions as to the 

 future lead concentrations in the 

 ocean can be made on the basis of 

 extrapolated industrial activity and of 

 models of the oceanic mixing proc- 

 esses. Very important is our knowl- 

 edge of the wind transport of lead 

 aerosols in the past through our read- 

 ing of the glacial record. 



The concept that the amounts of 

 pesticides contributed to the tropical 

 Atlantic by the trade winds are com- 

 parable to those carried to the sea by 

 major river systems was triggered by 

 analyses of both pesticides and their 

 carrier talc in permanent snowfield 

 records as well as in direct analyses 

 of river and atmospheric samples. 



Finally, the glaciers have recorded 

 the inputs of sulfur dioxide to the 

 atmosphere through the burning of 

 fossil fuels. The excess sulfur in the 

 atmosphere is now at least several 

 times natural levels. 



Examples such as these point out 

 one most important direction to go 

 for obtaining benchmark data to study 

 man's relationship to the chemistry 

 of the surface of the earth. 



Figure X-16 — PCB RESIDUE IN FISH, BIRDS. AND MAMMALS 



The table shows the ranges of concentration in parts per million that have been 

 measure in various organs of several species of fish (cf., Figure X-14 for DDT). 

 PCB's are not destroyed by usual waste-disposal methods. They enter the aquatic 

 environment through sewage effluents, land runoff from industrial wastes, and 

 condensation following incineration. PCB's have properties similar to DDT, but 

 they are more persistent and stable. 



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