1994 Arctic Ocean Section
sumably the result of microbial degradation. These enantiomeric "signatures"
of α-HCH are reflected in the overlying air, providing a direct indication of
The accompanying figures show the ERs of α-HCH in water and air with
latitude. In the Bering and Chukchi Seas the ERs are greater than 1.00, indicat-
ing a degradation of ()α-HCH relative to (+)α-HCH. Selective breakdown
of (+)α-HCH in the Arctic Ocean and the Greenland Sea reverses the ERs to
less than 1.00. These enantiomeric profiles are also found in air samples col-
lected over open-water regions, indicating volatilization of α-HCH from surface
water. The α-HCH in air over the ice cap was near racemic. Fugacity ratios at
higher latitudes also show the potential for α-HCH to volatilize (this work and
Falconer et al. 1995), but fluxes are probably inhibited by the ice cover.
Using the ER of α-HCH provides a way of distinguishing α-HCH that has
been microbially processed and recycled to the atmosphere by the oceans from
"fresh" α-HCH that has undergone aerial transport from source regions.
Enantiomers of chiral pesticides, such as α-HCH, chlordanes and heptachlor,
may also prove useful for tracing water masses with different ER signatures
when employed with traditional tracers such as salinity, temperature, nutri-
ents and dissolved oxygen.
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