Spatial Differences in Persistent Organochlorine Pollutant Concentrations between the Bering and Chukchi Seas (1993)

During August-September 1993, a joint Russian-United States expedition to the Bering and Chukchi Seas took place. Surface water samples were collected from 21 sites and separated into dissolved (duplicates) and suspended solids; 19 sediment and 6 air samples were also collected. These samples were analysed for 19 organochlorine pesticides, 11 chlorobenzenes and 113 PCB congeners. The report provides data on selected compounds which occured in 75% of the water samples. Highest water concentrations were observed for HCH in open waters north and south of the Bering Strait, both regions being similar (α-HCH; 2.2 ng/L and lindane: 0.35 ng/L). Air levels observed were also constant (α-HCH; 0.041 ng/m3, lindane: 0.0093 ng/m3). Suspended solids and air particulares contributed little to the concentrations in their respective media, an observation common to all analytes except for the PCBs and the DDT residues. The ∑PCB concentrations in water were higher in the Bering Sea area compared to the Chukchi Sea (1.0 vrs 0.67 ng/L) and lower for air (0.46 vrs 0.23 ng/m3). ∑DDT in water was higher in the Bering Sea than in the Chukchi Sea (0.23 vrs 0.15 ng/L) while in sediments and air, the Bering Sea concentrations were lower (0.95 vrs 1.6 ng/g and 36 vrs 56 pg/m3, respectively). Other organochlorine compounds for which data are presented include: pp′-DDE, pp′-DDT, dieldrin, HCB, 3 chlorobenzenes and 3 PCB congeners. Fluxes of all these chemicals through the Berin Strait are estimated; they ranged from 57 t/a (α-HCH) through 26 t/a (for ∑PCBs) to 0.2 t/a (pp′-DDE, dieldrin and 1,2,3-trichlorobenzene). Fugacity ratios for the HCHs and PCBs indicate the α-HCH is degassing in both the Bering and Chukchi Seas and that the γ-isomer is degassing in the Bering Sea and is close to equilibrium (weakly absorbing) in the Chuchi Sea; the ∑PCBs are strongly absorbing in both areas.