67, and 52). It should be noted that the BaP concentration in the 

 near-bottom water at these stations also had the low values (0.6 

 to l.Ong/1). 



In other regions the BaP concentrations in the upper 5 cm 

 layers of the sediment, which are the primary areas of PAH 

 accumulation (Bourcart era/., 1961; Larsene/a/., 1983), were 

 within 0. 1 1 to 1.7 )ig/kg of dry mass. The maximum BaP 

 concentration (4.5 |ig/kg) was measured in the shallow water 

 of the northern section in the Chukchi Sea (Station 49). A high 

 BaP concentration (0.87 |ig/kg) was also measured in the Gulf 

 of Anadyr at Stations 12 and 13 near the Chukchi coast, and 

 (1.7 |ig/kg) Station 43, and also in the center of the North 

 Polygon where it was 0.87 |J.g/kg. 



The general character of BaP distribution in bottom 

 sediments may be represented by the contours presented in 

 Fig. 2. It is evident that the spatial BaP distribution in bottom 

 sediments has quite a sophisticated structure with pronounced 

 concentration maxima regions. The position of areas with 

 maximum BaP concentrations in the sediment correspond to 

 the central portions of the northern section of the Gulf of 

 Anadyr, St. Lawrence Island, the central part of the Chirikov 

 basin, and the Central part of the investigated area of the 

 Chukchi Sea. 



1 • 9 BaP content _ 

 IL^ 6 



mg/kg dry weight 



[7] BaP content 



undetermined 



Chukchi Sea 



Bering Sea 



H 



Fig. 2. Concentration contours for BaP measureii in the lop 5 cm-layers of 

 sediment in the Bering and Chukchi Seas (August 1988). 



BaP accumulation was recorded in bottom sediments 

 (Tsyban et al., 1987) in previous studies as well (1981 and 

 1984). Incidentally. BaP levels at a number of sampled stations 

 showed no significant change over this time (Fig. 3 ), indicating 



11 '^°"h I 



^ Polygon (-P 



Bering Sea 



o 



1 



tdSl 



Polygon 



South 

 Polygon 



I 

 I 



D- 



02 



1988 



BaP content 

 mg/kg dr>' 

 weight 



Fig. 3. Comparisons of the concentrations of BaP measured over time in 

 surface sediments collected in 1981, 1984 and 1988 from similar 

 locations in the Bering Sea. 



a relatively constant processing of this constituent at these 

 locations. However, in general the total BaP accumulation in 

 bottom sediment of the Bering Sea and the Chukchi Sea is 1 to 

 2 orders of magnitude lower than in impacted sea systems 

 ( Tsyban etal.. 1985} and corresponds to the levels characteristic 

 of relatively clean regions such as the western coast of Greenland 

 (Mallet e/ a/., 1979). 



Benzo(a)pyrene distribution in the seawater showed a 

 significant impact on the biotic component of this system, 

 which was expressed, in particular, in the accumulation of this 

 toxic compound in aquatic biota, especially in the phytoplankton. 

 Earlier, in the investigated periods of 1981 and 1984. we 

 showed their presence in all of the samples of plankton taken 

 in the Bering Sea (phytoplankton and zooplankton). Its 

 content in plankton organisms was at the level of 10' to 

 10' |ig/kg dry wt. 



In 1988. BaP was recorded in all 26 samples of plankton 

 organisms taken at 22 stations in the Bering Sea and the 

 Chukchi Sea. and in most cases. BaP content in plankton was 

 within 0.2 to 0.9 |ig/kg (469^ of the samples) and 2.0 to 

 2.6 |ig/kg (23% of the samples). 



As one can see from Fig. 4. the highest BaP accumulation 

 in plankton in the Bering Sea, 10.2 to 10.6 |i g/kg, was in the 

 areas in the northern part of this area near the shallow water of 

 the St. Lawrence Island, the North Polygon, and Station 100 in 

 the Chirikov basin. 



311 



