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

observed from the Ice Island in the upper well mixed surface
layer. Aagaard and Coachman (1975) estimated that the total
annual inflow to the Arctic basin from runoff and the Bering Sea
was 5 x 1012 m3 while the total volume of the upper 50 m of the
Arctic Basin is about 4 x lo1* m3. It is evident that these
inflowing sources of water cannot account for the observed
concentrations.
Extrapolation of organochlorine concentrations vs salinity
through the halocline suggests that Atlantic core water has very
low concentrations of all compounds monitored. Total HCH
concentrations at the maximum depth sampled (280 m) , for example,
were less than 200 pg/L or about 50 times lower than
concentrations in the surface layer.
The hypothesis that dense cold water formed on the shelves
in winter, as a result of brine drainage, maintains the cold
halocline separating the surface layer from Atlantic water (see
for example Aagaard et all 1981) suggests that there might be an
organochlorine signature in this water assuming that water
generated on the shelf has higher organochlorine levels. There
was no corresponding concentration maximum detectable in any of
the organochlorines monitored. Concentrations of HCH for
instance, at the depth of the nutrient maximum, were in the range
of values calculated on the basis of salinity assuming a
conservative mixing of surface water and Atlantic core water.
There was a change in the ratio of &:trans chlordane (Section
5.1.2) however at a depth of 100 m which may be indicative of a
continental shelf source of chlordane at that depth.
Although no single source or transport mechanism is
responsible for the observed distribution and concentrations of
all organochlorines in the surface waters of the Arctic Ocean,
atmospheric input is clearly an important factor. Regional
influences in the shelf areas as a result of the input of river
water may result in local anomalies. However, the Ice Island was
well removed from any direct influence of river drainage and
concentrations probably reflect those over much of the Arctic
Ocean. Direct and indirect atmospheric input with contributions