Distribution of Chlorinated Hydrocarbon Pesticides and PCBs in the ...

Island that are equivalent to those obsesved in the deep sea
(Table 4.4). Low concentrations of suspended particulate matter
at all depths, but especially below the upper mixed layer in the
Arctic ocean should lead to low rates of sedimentation and
increased residence time of particle-reactive srganochlorines in
the water column. Tanabe and Tatsukama (1983), estimated a much
shorter residence time for DDT and PCBs (0.2 - 0.4 yr) in the
mixed layer than for the more soluble HCHs (5 - 10 yr).
Organochlorines adsorbed to suspended particles are available for
consumption by grazing zooplankton, and rapid removal from the
water column can occur as aggregated particles sediment (Osterroht
and Smetacek 1980, Iseki & d., 1981). The impact of these
biological processes for transfer of organochlorines through the
water column may be enhanced by the low concentration of suspended
particles and low sedimentation rates in the Arctic ocean.
The association of these compounds with particulates and
their accumulation in biota (Section 5.2) is reflected in the
presence of PCBs and DDT (one sample) in surface sediments despite
their low abundance in seawater.
5.2 Biomagnification of Organochlorines
Concentrations of organochlorines in plankton from the
Ice Island are compared with recent published plankton data for
other oceanic regimes in Table 5.2. Concentrations in plankton in
the Arctic Ocean are among the lower range of values reported for
oceanic plankton. Plankton data were also compared with under ice
and benthic amphipods from the Ice Island and with fish, seal and
Polar Bear tissue from the eastern Canadian Archipelago in Table
5.3. There were higher concentrations of all compounds in tissues
of amphipods relative to zooplankton with benthic amphipods, in
particular, 2. cicada, having higher concentrations than g.
Pitoralis captured under ice. Not all compounds are concentrated
to the same extent however. PCB and DDT concentrations were
almost two orders of magnitude higher in benthic amphipods than in
zooplankton while the concentration in under-ice animals was only