41 



TABLE 1.— TOXIC ELEMENTS OF CRITICAL IMPORTANCE IN MARINE POLLUTION BASED ON POTENTIAL SUPPLY 

 AND TOXICITY, LISTED IN ORDER OF DECREASING TOXICITY 



' After Bertine and Goldberg (1971) (except for fossil fuel production of cadmium). 



2 Water quality criteria: Concentration considered to pose minimal risk of deleterious effect. After Waldichuk (1972), 

 NAS (in press). 



3 Value from 3d annual report. Council on Environmental Quality, 1972. The total includes addition to soil and thus mav 

 be an overestimate. 



To put this index into iTerspeotive, the area of ocean surface so modified can 

 also be computed. The mixed layer of the ocean is of the order of 100 meters in 

 depth and the area of ocean which could be contaminated to this depth by 

 mercury, for example, as a result of the combustion of fossil fuel would -be 

 equivalent to 160,000 square kilometers or 61,500 square miles. This area is almost 

 equal to the land area of the state of Washington represented by the Chairman of 

 the Committee on Commerce, Senator Magnuson. It is almost twice the area 

 of South Carolina represented l)y Senator Hollings. Chairman of the Subcom- 

 mittee on Oceans and Atmosphere. It is clear that we are not talking about an 

 insignificant problem for mercury, which presents the most serious hazard, or 

 even for some of the other elements which would affect smaller volumes of 

 water or areas of the sea. Another i)ersixK»tive is given by computing the time it 

 would take to add this concentration of material to all of the water in the ocean. 

 Using mercury again as an example, it would take 10,000 years to contaminate all 

 of the oceanic waters to the indicated level of toxicity. This is not a very mean- 

 ingful calculation, however, because the oceans are not uniformly mixed and the 

 concentration at the locality where the pollutant is introduced will inevitably 

 increase more rapidly than the average for the whole ocean. 



Chlorinated hydrocarbons 



A wide variety of synthetic organic chemicals are also reaching the environ- 

 ment, particularly the chlorinated hydrocarbons such as DDT (and its decompo- 

 sition products) and polychlorinated biphenyls (PCB's). These are not readily 

 biodegradable, and the ocean is the ultimate sink for such compounds. Woodwell, 

 et al. (1971) have modelled the circulation of DDT in the biosphere and they 

 conclude that the largest reservoir for DDT is in the atmosi)here, but also that 

 the amount not decomposed by ultraviolet rays in the troposphere will ultimately 

 be added to the surface of the sea. If production of DDT stops in 1974 the model 

 predicts maximum concentrations in the mixed layer of the sea (upper 100 

 meters) in 1971 after which it would decrease to 10 i>ercent of the maximum by 

 1993. If production were to increase, however, the concentrations in both the 

 sea and the atmosnhere would also increase.' 



Harvey, et al. (1972) found substantial concentrations of DDT and its break- 

 down product. DDE (up to 100/ig/kg wet wt. in a shark) and even higher levels 

 of PCB's (up to 1056 Mg/ks wet weight in a dolphin) in a variety of orga- 

 nisms collected from the oiien sea manv miles from land confirming the probabil- 

 ity of atmospheric transport. As exi>ected, these compounds are concentrated in 



