(e.g., atmosphere, water, biota [plankton, benthos and fish], 

 sediment, and suspended matter). The levels of these 

 organochlorines were typical ofthose found in other neighboring 

 arctic areas, which indicates that there are no local .sources of 

 contamination. One especially interesting observation 

 concerning the levels of HCH" s in surface water was a suggestion 

 of an increasing gradient of concentration with increase in 

 latitude. This supports a theory that these compounds are 

 released into the atmosphere from warm seawater near the 

 equator, and they condense in the colder waters at the poles. 

 There was also evidence, from careful studies of the equilibrium 

 partitioning of the a and y isomers at the air-water interface, 

 that the present levels of the y isomer (Lindane) was on the 

 increase in the Bering-Chukchi Sea area. Trace metal 

 concentrations were measured for the first time in this area. 

 Levels were typical of pristine areas, and no local sources were 

 indicated. Cadmium, however, may require future study, since 

 biomagnification to moderate levels was noted in some of the 

 biota. 



Microbial degradation of selected congeners of PCB was 

 observed using laboratory incubations of isolates from the 

 region. Rates under these conditions were most rapid for the 

 lower chlorinated homologs, i.e., 95 to \00'7c reduction of the 

 dichlorobiphenyls in 20 days; and less for each succeeding 

 increase in chlorine number, with only 7% reduction of some 

 of the hexachlorobiphenyl htimologs. The activities also 

 varied with the structural position of the chlorines. Studies of 



photochemical degradation of PCB in in situ tests indicated that 

 the rates for photooxidati ve breakdown were much slower than 

 microbial degradation rates. However, many of the 

 congeners resisting microbial breakdown were degraded 

 in the photochemical tests. In similar tests with BaP, it was 

 found that the rates for BaP degradation by microbial action 

 were comparable to the rates for photochemical decay. These 

 tests demonstrate that even in ecosystems such as the easily 

 damaged and cold waters of the Bering-Chukchi Sea 

 possess the capability to cleanse themselves of man-made 

 pollutants. 



Several interesting findings emerged from the benthic 

 studies. There were several sites where evidence for petroleum 

 seepage was observed. This confirms the possibility that there 

 may be underlying petroleum deposits in the area. Based on 

 isotope and carbon data from the bottom, it was noted that there 

 is a gradual east to west gradient and high to low concentration 

 of terrigenous source carbon across the areas of each of the 

 major basins. The evidence suggests that most of the land- 

 based carbon is supplied from the Alaskan coastline to these 

 major basins. 



Contour plots of dissolvedhumics in surface water samples 

 indicated that the maximum levels were often displaced from 

 the areas where actual algal blooms were occurring. This 

 suggests that monitoring for these resistant forms of dissolved 

 organic matter might provide a means to measure the locations 

 and source strengths of previous blooms. 



406 



