Fróðskaparrit - 01.07.2004, Page 113

KYKSILVUR í FØROYUM - EIN GJØGNUMGONGD AV TØKUM DÁTUM
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um concentrations have varied markedly,
between 0,5 and 1,2 mg/kg in the 25-31 cm
group in 1999 and 2001 respectively. In the
Fig. 10, the mercury concentrations for two
size groups, the 20-25 cm and 25-31 cm
fork length groups, in the three succeeding
years are given. For cadmium it is apparent
that there is a relation between fish size and
cadmium concentration, in that the cadmi-
um concentration in the smaller size group
is always lower than or equal to the one in
the larger group. Although increasing cad-
mium and mercury concentration in groups
of increasing age/length has been shown to
be the rule rather than the exception within
the single study years (Olsen et ai, 2003)
the individual and between year variation is
so large as to incur a closer investigations
of its source in 2004. It is hard not to inter-
pret this variability as stemming from local
sources, however, the fact that this variation
in mercury is mirrored also in PCB and
DDT concentrations (as found by inspec-
tion of raw data) makes such an interpreta-
tion a bit dubious.
Comparing the metal concentrations of
sculpin from Kaldbakfjord with those from
similar monitoring in Greenland (Riget et
al., 2003) where the highest mercury con-
centrations in shorthorn sculpin (Myoxo-
cephalus quadricornis) in the 1999-2000
was found in Ittoqqortoormiit in fish of
length approx. 25 cm, and which amounted
to 0,061 mg/kg liver, it is apparent that the
level in the Faroese sculpin of similar
length is more than ten times higher. For
cadmium however, the concentrations in
the Greenland sculpin and the Faroese ones
are more comparable, but also for cadmium
there are large individual and annual varia-
tions in the Faroese material. The selenium
concentrations in the Faroese sculpin (Fig.
10) are similar to those in Greenland, al-
though somewhat higher.
Analyses of dab (Limanda limandá)
from the coastal area off Kirkjubøur show
relatively low values of mercury, in the
range 0,02-0,03 mg/kg muscle (Dam,
2000), compared to for instance dab in Nor-
way where mercury concentrations in the
range 0,04 mg/kg-0,09 mg/kg muscle were
found in 1998 (Green et al., 2000) and to
levels in Denmark, where mercury in floun-
der (Platichtus flesus) and plaice (Pleu-
ronectes platessoides) were found to be in
the range 0,12-0,25 mg/kg and 0,05-0,07
mg/kg respectively (Markager et al., 1998).
Flounder were analysed in the Norwegian
JAMP as well, and the concentration range
in this species was somewhat broader than
in dab, spanning from 0,04 mg/kg to 0,26
mg/kg muscle in 1998 i.e. the upper end of
this range is aligned with the Danish results
(Markager et al., 1998; Green et al., 2000).
Thus it appears that mercury concentra-
tions in the fish in shallow coastal areas of
the Faros Islands are low compared to Nor-
way and Denmark, but elevated at least for
sculpin at one site, compared to the Green-
land coastal environment.
In 1977-1984 mercury was analysed in
halibut larger that 60 kg full weight which
were caught in Faroese waters (Priebe,
1984). In all, muscle samples from 377 in-
dividuals were analysed, and the results
were that in 28,4% of the fish a mercury
concentration in the range 2,0-3,5 mg/kg
was found. In approx. 30% of the fish, the