Aliphatic and aromatic petroleum hydrocarbons were 

 ubiquitous in the sediment from the study area. Generally, 

 hydrocarbon concentrations were low and similar to previous 

 reports. The occurrence of high fluorescence intensity and R 

 ratio values and GC-derived indicators suggests the presence 

 of microseepage at several locations; this implies that underlying 

 petroleum deposits may exist. Low level polyaromatic 

 hydrocarbon (PAH) concentrations (<100 ppb) appear to be 

 related to combustion sources. 



Specific studies on benzo(a)pyrene (BaP) distribution 

 were conducted, with the assumption that BaP was a good 

 model compound for the other PAH's in the system. The 

 spatial and vertical distribution of BaP in the water of the 

 Bering Sea was relatively uniform, having an average value of 

 3.5 ng/1. Similar concentrations were observed in previous 

 collections from these areas in 1981 and 1984. A relatively 

 high BaP content was recorded in the Chirikov basin. 

 Benzo(a)pyrene concentrations in sea ice samples averaged 

 about 15 ng/1; in bottom sediments it was 0.7 to 

 1.7 |ig/kg dry wt. Benzo(a)pyrene concentrations in plankton 

 and neuston. respectively, ranged from 0.2 to 10.0 and 0.6 to 

 10.0 )ag/kg dry wt. The concentration of BaP in benthic 

 organisms ranged from 0.05 to 13.0 |ig/kg on a dry weight 

 basis. Mixed PAH's were specifically characterized in several 

 compartments of the system. In the water, bottom sediments, 

 suspended sediment and biota of the Bering and Chukchi Seas, 

 10 PAH's were identified, of which eight are carcinogenic and 

 three of these, benzo(b)fluoranthene, benzo(k)fluoranthene, 

 and BaP, are highly carcinogenic. In the surface water layer, 

 BaP and pyrene prevailed. The overall concentration ip the 

 surface water layers did not exceed 5.1 ng/1, but in the near- 

 bottom layer it reached 24 ng/1. The total concentration of 

 PAH's in the suspended matter reached 1 1.2 ng/g. The total 

 concentration of PAH's in the plankton varied widely (12 to 

 677 |ig/kg) and for the neuston ranged from 20 to 1 88 |ig/kg on 

 a dry wt. basis. 



The first data for heavy metals for this area were recorded 

 on this expedition. Concentrations of copper in the water 

 varied from 0.0 1 to 0.46 |ig/l in the open areas of the Bering Sea 

 with an average value 0.08 )ig/l. Shallow-water stations 

 demonstrated a direct relation between copper concentration in 

 water and bottom sediments. The other heavy metal water 

 concentrations were as follows: cadmium ranged from <0.01 

 to 0. 1 3 |ig/l; manganese did not exceed 0.04 Hg/1; zinc varied 

 from <0.01 to 3.67 )ag/l; and lead varied from <0.01 to 



1 .03 |ig/l. In the sediment, the metals investigated (As, Cd, Co, 

 Cu. Pb, Mn, and Hg), with the exception of mercury, were 

 detected in all of the surficial samples (0-2 cm). The 

 concentrations of cadmium, cobalt, lead, mercury, and arsenic 

 appeared to be higher in the shelf areas. Downward fiuxes of 

 planktonic organisms and biogenic debris aie likely sources. 

 Arsenic and cadmium were elevated in most of the marine 

 biota. Tendencies for bioaccumulation rather than localized 

 pollution appear to be the cause. 



The average concentration of Cs'" for the entire area was 



2.4 Bq/m'. The vertical distribution of Cs'" in the Bering Sea 

 was homogeneous, but for the Chukchi Sea it was characterized 



by an elevated concentration in the bottom layers (ranging from 

 2.5 to 5.5 Bq/m') and an overall average of 3.1 Bq/m\ The 

 observed homogeneity of the Cs' " indicates the lack of local 

 input of this material. The maximum possible contribution of 

 "Chernobyl's" Cs'" did not exceed 6%. 



Microbial degradation of many of the PCB congeners ( 1 9 

 of 70 that were added) was observed. Of these 19 congeners, 

 the dichlorobiphenyl homologs were degraded the fastest, 95 

 to 100'?^^, and the trichloro homologs next, 64 to 66%, then the 

 tetra's, 10 to 58% and the penta's at 36 to 44%. The 

 hexachlorobiphenyls (HCB's) were degraded only slightly, 

 7%. With photochemical degradation of PCB' s in seawater, it 

 was found that those congeners of the PCB mixture that did not 

 undergo microbial transformation were often more susceptible 

 to photochemical decomposition. Hexachlorobiphenyls and 

 higher-chlorinated compounds did not undergo any reaction. 

 The photochemical degradation proceeded with direct 

 dechlorination accompanied by isomerization and condensation. 

 The rate of the reaction depends on the molecular configuration, 

 with locations 2,2' or 4,4' favoring photochemical attack. 

 Overall rates of photochemical degradation were slower than 

 the rates for microbial breakdown. Thus microbial breakdown 

 is probably more important to the removal of PCB's than are 

 photochemical processes. It was also determined that the 

 presence of PAH" s could inhibit the photochemical degradation 

 processes by 10%. 



Microbial degradation experiments with BaP showed that 

 pelagic microflora of this region can transform between 8 and 

 45 percent/time of the total concentration of BaP. Maximum 

 rates were observed in the Gulf of Anadyr, at the North 

 Polygon, and in the southwest Chukchi Sea. In 21 -days of 

 incubation, 84% of the added BaP was destroyed. The 

 photochemical trans fnrmation is described by a formal first- 

 order kinetic equation. The rate constant values was 0.69 h. 

 Based on relative rates of reaction for microbial versus 

 photochemical breakdown of BaP, photoxidation shares in 

 importance with microbial processes. 



Natural populations of phyto-, microzoo-, and, 

 bacterioplankton were tested for their susceptibility to some 

 representative natural contaminants (BaP, PCB' s, Cu, and Cd). 

 Primary productivity, bacterial respiration, and cell growth 

 were monitored. Susceptibility was found to vary with pollutant 

 type, collection location, and with the endpoint being monitored. 

 The range of toxicity from the most toxic to the least were as 

 follows: BaP.Cu, PCB.andCd. For BaP, the range of LD,„ to 

 phytoplankton wasO. 1 to 10 |ig/l for primary productivity and 

 for microzooplankton, 0.05 to 7 |ig/l for cell growth. 

 Bacterioplankton had a higher tolerance for all the chemicals 

 than the phytoplankton or microzooplankton, and in some 

 cases their activity was stimulated by the toxicants. This 

 behavior was believed to be an indirect effect caused by 

 increased organic matter resulting from the death of the other 

 organisms in the mixed cultures. Chukchi communities were 

 found to be more sensitive than the Bering Sea organisms to 

 BaP and PCB but less sensitive to Cu and Cd. Characterization 

 of an area of low resistance near St. Lawrence Island agreed 

 with similar findings in 1984 for this area. Comparing the 



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