kinetic model was developed for the elimination and uptake processes of PCBs in the
porpoises. In the model, a clear trend between the enantiomeric ratios and the ratio
between PCB 153 and PCB 101 was confirmed. Due to the fact that PCB 153 is one
of the most persistent PCB congeners in marine mammals and PCB 101 considered
to be easily metabolised, this tendency confirms that the enantiomeric ratio most
likely reflects the proportion of the metabolised congener. The authors concluded
(Chu et al. 2003a, b) that the determination of enantiomeric profiles in wildlife,
combined with information on their anthropometric data, health status, diet and
habitat conditions, might be good indicators of pollution status in pristine marine
environments.
A study on a marine Arctic ecosystem, the biosphere of the North Water Polynya
(NOW), was reported by a Canadian research group (Warner et al. 2005). The
enantiomer distribution of atropisomeric PCBs was examined in a typical Arctic
marine food web. Typical members, representing different trophic levels were
pelagic zooplankton, Arctic cod (Boreogadus saida), seabirds and ringed seals
(Pusa hispida). Along with previously reported studies on similar species, this
investigation confirmed biomagnification in the NOW food web. The heredetermined, highly non-racemic enantiomeric fractions (EFs) in l seabird species
and ringed seals indicated biotransformation and selective bioaccumulation of
atropisomeric PCBs. However, racemic EFs were found in their prey (zooplankton
and fish), which, in turn, indicates, that biotransformation in the top predators are the
main reason for the non-racemic EFs determined. The here-presented results are
consistent with previously reported biotransformation activity for chiral organochlorine pesticides in these species and demonstrate the versatility of chiral analysis of
PCBs for the assessment of biotransformation within Arctic food webs.
8.2.2 Terrestrial Ecosystems
In the initial phase of research on the behaviour of chiral pollutants in the environment, enantioselective analyses in terrestrial ecosystems largely focused on the
questions: Can the conclusions drawn from marine biota analyses with regard to
enantioselective transformation of xenobiotics be transferred to terrestrial animals?
Can species-dependent and/or concentration-dependent effects be observed? Early
investigations addressed these scientific questions were Möller et al. (1993) determined the enrichment of α-HCH enantiomers as determined in fat, liver and brain
tissue samples of sheep (Ovis ammon L.) bred in the northern German state of
Schleswig-Holstein (Table 8.14; Fig. 8.20). In fat and liver, a depletion of the (+)enantiomer was observed, while in brain vice versa the (+)-enantiomer is dominating. These values were compared with those from marine biota like blue mussels
(Mytilus edulis L.; ER between 0.67 and 0.89), flounder (Platychthys flesus L.; ER
0.80–0.94), Common Eider duck (Somateria mollissima (L.); liver: ER ¼ 1.4–1;
170
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants
porpoises. In the model, a clear trend between the enantiomeric ratios and the ratio
between PCB 153 and PCB 101 was confirmed. Due to the fact that PCB 153 is one
of the most persistent PCB congeners in marine mammals and PCB 101 considered
to be easily metabolised, this tendency confirms that the enantiomeric ratio most
likely reflects the proportion of the metabolised congener. The authors concluded
(Chu et al. 2003a, b) that the determination of enantiomeric profiles in wildlife,
combined with information on their anthropometric data, health status, diet and
habitat conditions, might be good indicators of pollution status in pristine marine
environments.
A study on a marine Arctic ecosystem, the biosphere of the North Water Polynya
(NOW), was reported by a Canadian research group (Warner et al. 2005). The
enantiomer distribution of atropisomeric PCBs was examined in a typical Arctic
marine food web. Typical members, representing different trophic levels were
pelagic zooplankton, Arctic cod (Boreogadus saida), seabirds and ringed seals
(Pusa hispida). Along with previously reported studies on similar species, this
investigation confirmed biomagnification in the NOW food web. The heredetermined, highly non-racemic enantiomeric fractions (EFs) in l seabird species
and ringed seals indicated biotransformation and selective bioaccumulation of
atropisomeric PCBs. However, racemic EFs were found in their prey (zooplankton
and fish), which, in turn, indicates, that biotransformation in the top predators are the
main reason for the non-racemic EFs determined. The here-presented results are
consistent with previously reported biotransformation activity for chiral organochlorine pesticides in these species and demonstrate the versatility of chiral analysis of
PCBs for the assessment of biotransformation within Arctic food webs.
8.2.2 Terrestrial Ecosystems
In the initial phase of research on the behaviour of chiral pollutants in the environment, enantioselective analyses in terrestrial ecosystems largely focused on the
questions: Can the conclusions drawn from marine biota analyses with regard to
enantioselective transformation of xenobiotics be transferred to terrestrial animals?
Can species-dependent and/or concentration-dependent effects be observed? Early
investigations addressed these scientific questions were Möller et al. (1993) determined the enrichment of α-HCH enantiomers as determined in fat, liver and brain
tissue samples of sheep (Ovis ammon L.) bred in the northern German state of
Schleswig-Holstein (Table 8.14; Fig. 8.20). In fat and liver, a depletion of the (+)enantiomer was observed, while in brain vice versa the (+)-enantiomer is dominating. These values were compared with those from marine biota like blue mussels
(Mytilus edulis L.; ER between 0.67 and 0.89), flounder (Platychthys flesus L.; ER
0.80–0.94), Common Eider duck (Somateria mollissima (L.); liver: ER ¼ 1.4–1;
170
8 Enantiomer-Specific Fate and Behaviour of Chiral Contaminants