from the ship. Benzo(a)pyrene was extracted from 1 1 samples 

 by triple extraction with benzene. Final processing of the 

 benzene extracts (100 ml volumes) were carried out in the 

 laboratory in Moscow. 



Bottom sediments were collected using an OKEAN dredge, 

 which removed a 0.25 m- area of the bottom without disturbing 

 its stratification. A 5-cm depth was removed from these grab 

 samples (50 to 100 g). These were then dried at 60°C, wrapped 

 in aluminum foil, placed in a plastic bag, and stored for later 

 analysis. 



Plankton samples were collected using a Gedy net, which 

 was allowed to drift behind the ship at 45- to 70-m depths for 

 1 h. The collected biomass was dried at 60°C to a constant 

 weight and stored until analyzed at the laboratory in Moscow. 



Samples of neuston organisms were obtained using a 

 surface neuston net "nHC-2" (see Subchapter 5.2.5, this 

 volume). The samples were dried and prepared for subsequent 

 analysis as described above. 



Chemical Analysis 



Quantitative Determination of Benzo(a)pyrene in Seawater 



The benzene extracts of the samples that contained the 

 benzo(a)pyrene (BaP) were concentrated to 1 ml volumes and 

 chromatographed using thin layer chromatography using 

 alumina coated plates. The running solvent was 

 heptane:benzene:acetone (100:60:6.7). The BaP-containing 

 spot on the plate was scraped off and eluted with acetone. The 

 acetone solvent was then exchanged with n-octane. 



Quantitative determinations of the BaP dissolved in the 

 n-octane solutions were carried out by fluorescence analysis 

 using the Shpolsky effect (Shpolsky et al., 1952; Fedoseyeva 

 et al. 1968) at 196°C on a AOC-12 spectrograph using 

 appropriate standards. BaP and others. 



Sensitivity of the method allowed quantitation of BaP 

 down to 1x10 '"g/ml. with an error of less than 10%. 



Determination of Benzo(a)pyrene in Sediment and Biota 



Bottom sediments, plankton, and neuston were crushed to 

 a powder. Portions of 3 to 5 g were extracted using 200 ml of 

 benzene in a Soxhlet unit for 12- to 18-h periods. After 

 concentration and chromatographic separation by thin layer 

 chromatography on alumina plates using a (9: 1 ) benzene:acetone 

 developing solution, the BaP spots were scraped off and 

 quantitatively analyzed using the fluorescence technique 

 discussed earlier. 



Results and Discussion 



The Third Joint US-USSR Bering & Chukchi Seas 

 Expedition ( August to September 1 988 ) studied biogeochemical 

 cycling of PAH's in marine ecosystems of the northern oceans 

 using benzo(a)pyrene as a model compound. The expedition 

 was a continuation of previous investigations in the Bering Sea 

 ( Izrael eta!., 1987), and also was expanded to include the Gulf 

 of Anadyr, the Chirikov basin and the Chukchi Sea, where this 

 work was carried out for the first time. 



By positioning the sampling locations where work began 

 in 1981 and 1984, as well as positioning them at new stations 

 in the Gulf of Anadyr, we were able to cover both the deep- 

 water areas of the Bering Sea (the East and South Polygons) 

 and the northern shallow-water areas of the continental shelf. 



At the high latitude stations, BaP concentrations exceeded 

 10 ng/1 in 28 of the 45 surface water samples. The highest 

 concentration values that were measured in these regions are 

 shown in Fig. 1 for the water. 



Fig. 1. Distribution of the the highest benzo(a)pyrene concentrations (those 

 >5 ng/1 ) measured in waters of the Bering and Chukchi Seas ( August 

 1988). 



The BaP spatial distribution in water of the southern 

 Bering Sea and East, South, and North Polygons was generally 

 homogeneous, without the spottiness characteristic of the 

 previous expeditions (Tsyban et al., 1986; Volodkovich etal., 

 1987). The average concentration in the seawater was 

 3.5±0.48 ng/1. Notice that even taking into account all of the 

 values, including the highest ones (up to 80 ng/1), the average 

 BaP concentration did not exceed 9.3 ng/1, which is much 

 below the levels recorded on the previous expedition in 1984. 



The majority of the BaP concentrations in the Bering Sea 

 in August 1988 fell between 2 and 5 ng/1, which corresponded 

 to the natural low levels of BaP in seawater reported by other 

 investigators. In many cases, the maximum values found were 

 only 0.4 to 0.6 ng/1. The highest BaP concentrations were 



309 



