Fróðskaparrit - 31.12.2000, Síða 167

KANNINGAR AV KYKSILVRI OG ORGANOKLORIDUM
I EINSTØKUM HAVSUGDJORUM IFØROYUM
171
whales. The most immediate explanation
for this phenomenon would be that the
adult seal males migrate to more polluted
areas during their lifetime (perhaps early
“adulthood”). This would also be consis-
tent with the present knowledge of the grey
seals in the Faroe Islands.
There are, however, additional possible
reasons for these differences. For example,
sample characteristics, such as group mean
age and the general “representativity” of
the sample, may be a reason, as well as
those unique differences that are inherent in
the specific species. In addition, factors,
which may be termed combined species
and general socio-ecological differences,
which lead to variability in frequency of re-
production, etc. will influence the intake
and elimination of pollutants. Possible dif-
ferences in diets and foraging areas among
females and males of the same species will
also contribute to these differences.
It appears that a combination of factors
contribute to very high concentrations of
persistent organic pollutants in a few adult
male seals. Individual variations are more
moderate among the pilot whales, however,
and it is plausible that pilot whales, which
live in pods, as a species represent a more
homogeneous group. This is also suggest-
ed by the similarities in the persistent or-
ganic pollutant concentrations in the two
pods studied. Review of the pollutants vs.
body length curves (Figs. 2, 8, 11, 14) for
the white-sided dolphins reveals a shortage
of juvenile males in this sample, and per-
haps also an under-representation of adult
females. Given these uncertainties, it
seems premature to try to set the present
fmdings into a model. However, compari-
son of the pollutants vs. body length curves
for the white-sided dolphins against the
curves plotted for the pilot whales indicates
that the mature males of the former species
are accumulating the lipid soluble pollu-
tants at a much higher rate than the pilot
whale males.
Correlations
Review of the ”highest concentration” col-
umn in Table 19 reveals that the com-
pounds analysed may be sorted into levels.
The highest level of concentration is the
DDT group, which thus accounts for the
highest mass of the analysed pollutants in
the blubber tissue. The DDT group is fol-
lowed by PCB, toxaphene, and then the
chlordanes. There is a significant drop to
the mercury level and subsequently to the
lowest level comprised of HCB, Mirex, and
13-HCH.
The Sum DDT in the adult male groups
are in the range 4,000 to 27,000 pg/kg lipid
with grey seals at the lower level and the
white-sided dolphins at the upper level,
with small margins only with the pilot
whales, which have average concentrations
of 18,000 and 24,000 pg/kg lipid in the Tór-
shavn 13 November 1997 and the San-
davágur pods, respectively. The PCB 7 for
the adult male groups ranged from 10,000
pg/kg lipid in the pilot whales of the Tór-
shavn 13 November 1997 pod to 11,500
pg/kg lipiđ in the white-sided dolphins to
13,000 pg/kg lipid in the Sandavágur pods
of pilot whales and the grey seals. B-HCH
was detected in three grey seal individuals,
but only at 5, 6, and 7 pg/kg lipid in a three-