Furthermore, it is worth noting that according to Fig. 8.28. α-HCH in the air over
the Canada Basin north of 75
N is racemic even, when the water is not. This is
possibly due to inhibition of sea-to-air gas exchange by ice cover, although the
fugacity ratios predict that the water is over-saturated (Jantunen and Bidleman
1996).
In 1996, Harner et al. (1998) carried out air-water gas exchange studies of
hexachlorocyclohexanes and the enantiomers of α-HCH in the Barents Sea and
eastern Arctic Ocean using a similar experimental and theoretical approach as
Jantunen and Bidleman (Bidleman et al. 1998a, b, c, d). Air and water samples
were collected aboard the Swedish icebreaker Oden during July–September, 1996,
where water samples were taken with a submersible pump lowered about 3 m below
the water line, while air samples of about 600 m
3 were drawn over 24 h through a
glass fibre filter followed by a polyurethane foam (PUF) trap.
The enantiomeric ratios of α-HCH in surface water ranged from 0.72 to 0.94 and
averaged 0.87Æ0.06 (n ¼ 21), indicating the selective transformation of (+)-α-HCH.
Mean ERs in four different zones that can largely be characterised by different
latitudes were as follows: latitudes 73–79
N: ER¼0.91Æ0.01; latitudes 80–87
N:
ER¼0.83Æ0.03; latitudes 85–88
N: ER¼0.89Æ0.04; latitudes 82–87
N:
0.83Æ0.09. Enantioselective breakdown of (+)-α-HCH was greater in subsurface
water, with ERs of about 0.2–0.3 at 250–1000 m, agreeing with results from the
western Arctic Ocean (Jantunen and Bidleman 1998). The range of enantiomeric
ratios in air samples was 0.87–1.00, with a mean of 0.95 Æ 0.03 (n ¼ 16). This result
suggests that the air sampled from the ship contained a mixture of non-racemic
α-HCH from volatilisation and racemic α-HCH transported from continental
regions.
Organochlorine contamination in the Northern Hemisphere has been studied
much more extensively than in the Southern Hemisphere, but organochlorine residues, including hexachlorocyclohexanes, have been found in Arctic air, water and
biota (Hoekstra et al. 2003a, b, c; Kelly and Gobas 2003; Borga and Bidleman 2005;
Jantunen et al. 2008; Bidleman et al. 2013a, b; Carlsson et al. 2014a, b; Jin et al.
2017). The global fractionation hypothesis predicts that chemicals released in the
temperate and tropical zones will be transported to the colder boreal and polar zones,
where they will have the tendency to reside for long periods of time. Therefore, it
appeared to be of high interest as to whether indications of enzymatic transformation
of α-HCH can be found in Antarctic regions (Jantunen et al. 1998a, b). During the
period from December 1997 to February 1998, air and water samples were collected
in the South Atlantic and the Southern Ocean to determine the air–water gas
exchange of α- and γ-HCH and the enantiomeric ratios of α-HCH. The cruise
track of the S A Agulhas was as follows: the research vessel left Cape town,
South Africa, on 30 November 1997, and proceeded south along 6
E reaching the
South African National Antarctic Expedition (SANAE) Base (70
S, 3
E) then
returning to Cape Town on 7 February 1998.
Water samples of 20–80 L were collected by a submersible pump beneath the
ship. Air samples were taken by drawing 700–1500 m
2 of air through a 20 Â 25 cm
glass fibre filter (GFF) followed by two polyurethane foam plugs (PUFs). Further
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
205
the Canada Basin north of 75
N is racemic even, when the water is not. This is
possibly due to inhibition of sea-to-air gas exchange by ice cover, although the
fugacity ratios predict that the water is over-saturated (Jantunen and Bidleman
1996).
In 1996, Harner et al. (1998) carried out air-water gas exchange studies of
hexachlorocyclohexanes and the enantiomers of α-HCH in the Barents Sea and
eastern Arctic Ocean using a similar experimental and theoretical approach as
Jantunen and Bidleman (Bidleman et al. 1998a, b, c, d). Air and water samples
were collected aboard the Swedish icebreaker Oden during July–September, 1996,
where water samples were taken with a submersible pump lowered about 3 m below
the water line, while air samples of about 600 m
3 were drawn over 24 h through a
glass fibre filter followed by a polyurethane foam (PUF) trap.
The enantiomeric ratios of α-HCH in surface water ranged from 0.72 to 0.94 and
averaged 0.87Æ0.06 (n ¼ 21), indicating the selective transformation of (+)-α-HCH.
Mean ERs in four different zones that can largely be characterised by different
latitudes were as follows: latitudes 73–79
N: ER¼0.91Æ0.01; latitudes 80–87
N:
ER¼0.83Æ0.03; latitudes 85–88
N: ER¼0.89Æ0.04; latitudes 82–87
N:
0.83Æ0.09. Enantioselective breakdown of (+)-α-HCH was greater in subsurface
water, with ERs of about 0.2–0.3 at 250–1000 m, agreeing with results from the
western Arctic Ocean (Jantunen and Bidleman 1998). The range of enantiomeric
ratios in air samples was 0.87–1.00, with a mean of 0.95 Æ 0.03 (n ¼ 16). This result
suggests that the air sampled from the ship contained a mixture of non-racemic
α-HCH from volatilisation and racemic α-HCH transported from continental
regions.
Organochlorine contamination in the Northern Hemisphere has been studied
much more extensively than in the Southern Hemisphere, but organochlorine residues, including hexachlorocyclohexanes, have been found in Arctic air, water and
biota (Hoekstra et al. 2003a, b, c; Kelly and Gobas 2003; Borga and Bidleman 2005;
Jantunen et al. 2008; Bidleman et al. 2013a, b; Carlsson et al. 2014a, b; Jin et al.
2017). The global fractionation hypothesis predicts that chemicals released in the
temperate and tropical zones will be transported to the colder boreal and polar zones,
where they will have the tendency to reside for long periods of time. Therefore, it
appeared to be of high interest as to whether indications of enzymatic transformation
of α-HCH can be found in Antarctic regions (Jantunen et al. 1998a, b). During the
period from December 1997 to February 1998, air and water samples were collected
in the South Atlantic and the Southern Ocean to determine the air–water gas
exchange of α- and γ-HCH and the enantiomeric ratios of α-HCH. The cruise
track of the S A Agulhas was as follows: the research vessel left Cape town,
South Africa, on 30 November 1997, and proceeded south along 6
E reaching the
South African National Antarctic Expedition (SANAE) Base (70
S, 3
E) then
returning to Cape Town on 7 February 1998.
Water samples of 20–80 L were collected by a submersible pump beneath the
ship. Air samples were taken by drawing 700–1500 m
2 of air through a 20 Â 25 cm
glass fibre filter (GFF) followed by two polyurethane foam plugs (PUFs). Further
8.2 Transformation/Accumulation of Chiral Xenobiotics in Higher Organisms
205