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

temperatures rose above 0°C. Our values of HCH in melted snow
samples in June were similar to Patton & a. Is (1988) values for
'toldM snow. The ratio of a1pha:gamma-HCH was 1.5 in June-
Lindane (gamma-HCH) values in June were the same as in the
previous August/September samples while alpha-HCH, concentrations
were 3 times lower. Reported vapour pressures for the two
isomers are similar and an increase in the alpha isomer relative
to the gamma isomer would be expected on the basis of the IJV
induced transformation of lindane to alpha-HCH. The lower
concentration of alpha-HCH therefore indicates a mechanism which
produces a more rapid loss of alpha-HCH than transformation of
lindane or is indicative of a difference in source material in
1987. Gregor (personal communication) indicated that values for
organochlorines in snow samples throughout the Canadian ~rctic
were lower in 1987 compared to 1986.
HCH concentrations are lower in ice than in seawater
probably as a result of loss through brine explusion during the
winter.
Concentrations of HCH1s measured in coastal and oceanic
waters have been reviewed by Harding (1986). HCH isomer5 are
the most water soluble of the organochlorines monitored (Table
5.1) and this property along with their abundance in air is
reflected in high levels of these compounds in seawater. ~evels
of aipha and gamma-HCH > 10 ng L-l occur in some coastal waters
near urban areas but values for oceanic surface waters are up to
an order-of-magnitude lower. Concentrations for C-HCH in the NW
Pacific and Bering Sea (1.3 and 7.3 ng L-I) span the range of
values observed at the Ice Island (5.1 + 0.5 ng L-I) (Table 4 -51
Concentrations of alpha-HCH and gamma-HCH of 7.1 and 0.8 r , g L-'
reported from 10 m depth in samples collected from the Ice :$land
in June 1987 (Patton & d. 1988) are about 40% higher than
average values for the mixed layer we measured in June 1986 [Table
4.5) . Differences in extraction methods used in each stud1 must
account for this variance.
There is a large reservoir of HCH in Arctic s~zface
water. Assuming a surface area of 1.3 x 1013m2 and an average 5