A different result was obtained from enantiomer-selective analysis of liver samples derived from the corresponding flounders (Platichthys flesus). The mean values
of the different test sites vary from 0.80 to 0.94 (Table 8.9), which reflect an
enzymatic transformation process that prefers common structural elements
represented by (+)-α-HCH. Since the enantiomeric ratios of α-HCH determined in
the liver samples of the flounders in the two test sites F1 and F2 show relatively low
variability for the respective areas, a comparison between these two data sets appears
to be feasible: In the Test site F1, a mean enantiomeric ratio of 0.8 Æ 0.05 was
determined for the flounders caught in January 1991, while the flounders caught
during the same period in the less polluted area F2 showed a mean value of 0.89 Æ
0.03. The result seems to support the assumption that a stronger enzymatic activity is
induced in the liver of the flounders caught in the highly polluted Elbe estuary than in
the liver of flounders living in the Eider estuary. However, it should be noted that the
effects observed by Pfaffenberger et al. is based on a consistent but small data set,
and, furthermore, the effect is only slightly beyond the error limits. In addition,
seasonal effects, for example, different input of pollutants into the sea during winter
and summer periods may modify the results. This is demonstrated by a comparison
of the enantiomeric ratios of α-HCH determined in flounders caught in the Elbe
estuary in January 1991 (mean value of 0.80 Æ 0.05; F1/samples # 6–9, Table 8.9)
and in June 1991 (mean value 0.94 Æ 0.04; F1/samples # 1–5). Therefore, caution
has to be applied when interpreting the flounder data summarised in Table 8.9 and
follow-up study should be encouraged in order to verify the here-presented
indications.
Meanwhile, several authors have addressed the scientific challenge posed by the
topic enantioselective transformation of α-HCH at low trophic levels (Hoekstra et al.
2003a, b, c; Borga and Bidleman 2005), organisms associated with higher trophic
levels like other domestic and wild birds (Corsolini et al. 2006; Yang et al. 2010a, b;
Liu et al. 2016a, b), Canadian wolverine (Hoekstra et al. 2003a, b, c), seals
(Hühnerfuss et al. 1993; Hummert et al. 1995; Klobes et al. 1998a, b, c; Moisey
et al. 2001; Fisk et al. 2002; Hoekstra et al. 2003a, b, c; Carlsson et al. 2014a, b),
whales (Hummert et al. 1995; Hoekstra et al. 2003a, b, c; Carlsson et al. 2014a, b)
and polar bears (Wiberg et al. 1998a, b, c; Ross et al. 2011a, b) applying chiral
selectors on the basis of modified cyclodextrin CSPs. The results are summarised in
Table 8.10.
In detail, different scientific aspects have been covered by the earlier studies
summarised above. For example, Hühnerfuss et al. (1993) compared the results of
tissue sample extracts of dead found harbour seals (Phoca vitulina L.) from the
German Bight and from hunted animals from Iceland, respectively, in order to study
the impact of different contamination levels on the enantioselective processes. In the
seal tissues obtained from animals of the German Bight, enantiomeric ratios of
1.5–4.5 were determined for blubber tissue, while brain tissue from the same animals
yielded enantiomer ratios of 7.9–19.9. These values have to be compared with those
from Iceland seals, that is, enantiomeric ratios in blubber 1.2–1.4 and in brain tissues
55.6, 66.2 and six values of nearly 1 (¼ infinite). Though the general tendency of
the data from both regions is comparable, the enantiomeric ratios in the blubber of
140
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants
of the different test sites vary from 0.80 to 0.94 (Table 8.9), which reflect an
enzymatic transformation process that prefers common structural elements
represented by (+)-α-HCH. Since the enantiomeric ratios of α-HCH determined in
the liver samples of the flounders in the two test sites F1 and F2 show relatively low
variability for the respective areas, a comparison between these two data sets appears
to be feasible: In the Test site F1, a mean enantiomeric ratio of 0.8 Æ 0.05 was
determined for the flounders caught in January 1991, while the flounders caught
during the same period in the less polluted area F2 showed a mean value of 0.89 Æ
0.03. The result seems to support the assumption that a stronger enzymatic activity is
induced in the liver of the flounders caught in the highly polluted Elbe estuary than in
the liver of flounders living in the Eider estuary. However, it should be noted that the
effects observed by Pfaffenberger et al. is based on a consistent but small data set,
and, furthermore, the effect is only slightly beyond the error limits. In addition,
seasonal effects, for example, different input of pollutants into the sea during winter
and summer periods may modify the results. This is demonstrated by a comparison
of the enantiomeric ratios of α-HCH determined in flounders caught in the Elbe
estuary in January 1991 (mean value of 0.80 Æ 0.05; F1/samples # 6–9, Table 8.9)
and in June 1991 (mean value 0.94 Æ 0.04; F1/samples # 1–5). Therefore, caution
has to be applied when interpreting the flounder data summarised in Table 8.9 and
follow-up study should be encouraged in order to verify the here-presented
indications.
Meanwhile, several authors have addressed the scientific challenge posed by the
topic enantioselective transformation of α-HCH at low trophic levels (Hoekstra et al.
2003a, b, c; Borga and Bidleman 2005), organisms associated with higher trophic
levels like other domestic and wild birds (Corsolini et al. 2006; Yang et al. 2010a, b;
Liu et al. 2016a, b), Canadian wolverine (Hoekstra et al. 2003a, b, c), seals
(Hühnerfuss et al. 1993; Hummert et al. 1995; Klobes et al. 1998a, b, c; Moisey
et al. 2001; Fisk et al. 2002; Hoekstra et al. 2003a, b, c; Carlsson et al. 2014a, b),
whales (Hummert et al. 1995; Hoekstra et al. 2003a, b, c; Carlsson et al. 2014a, b)
and polar bears (Wiberg et al. 1998a, b, c; Ross et al. 2011a, b) applying chiral
selectors on the basis of modified cyclodextrin CSPs. The results are summarised in
Table 8.10.
In detail, different scientific aspects have been covered by the earlier studies
summarised above. For example, Hühnerfuss et al. (1993) compared the results of
tissue sample extracts of dead found harbour seals (Phoca vitulina L.) from the
German Bight and from hunted animals from Iceland, respectively, in order to study
the impact of different contamination levels on the enantioselective processes. In the
seal tissues obtained from animals of the German Bight, enantiomeric ratios of
1.5–4.5 were determined for blubber tissue, while brain tissue from the same animals
yielded enantiomer ratios of 7.9–19.9. These values have to be compared with those
from Iceland seals, that is, enantiomeric ratios in blubber 1.2–1.4 and in brain tissues
55.6, 66.2 and six values of nearly 1 (¼ infinite). Though the general tendency of
the data from both regions is comparable, the enantiomeric ratios in the blubber of
140
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants