Fróðskaparrit - 01.07.2004, Síða 83

KYKSILVUR í LIVUR, EGGUM OG FJØÐUR
CEPPHUS GRYLLE FAEROENSISIN THE FAROEISLANDS
81
1999 2000 2001
Koltur Skúvoy Koltur Skúvoy Koltur Skúvoy
n 10 8 10 9 10 10
Mean Hg, mg/kg ww 0,510 0,514 0,361 0,299 0,324 0,326
Stddev. 0,186 0,122 0,113 0,097 0,09 0,085
Median Hg, mg/kg ww 0,44 0,48 0,34 0,34 0,33 0,32
min, mg/kg ww 0,35 0,39 0,16 0,14 0,182 0,19
max, mg/kg ww 0,97 0,73 0,55 0,42 0,449 0,437
d 15N, %o 9,89 10,54 10,60 11,23 11,40 12,65
d 13C, %o -21,22 -21,80 -20,10 -20,37 -19,36 -18,03
Table I Mercury (Olsen et al., 2003) and stable isotopes ofNitrogen and Carbon (Ólafsdóttir, 2002) in black
guillemot eggsfrom Koltur and Skúvoy in 1999-2001.
ilar to the level of mercury in the Faroese
birds. The mercury concentration in black
guillemot males appears to be elevated
compared to the Icelandic counterparts
(Fig. 1) with approx. 100% higher mercury
concentration than in the Icelandic birds. It
is worth noting however, that this high
mean includes an outlier, without whom,
the mean would be 1,2 mg/kg, and seen in
relation to the August 1996 value in Fig. 2
this appears to be the common mercury lev-
el, which is very similar to the Icelandic
one. Mean liver mercury concentration in
three specimens froin Franz Josef Land
Archipelago was reported to be 0,88 mg/kg
(Savinov et al., 2000). Generally speaking,
there is little data available for comparison,
the data available indicates however that
the level of mercury in the Faroese black
guillemots is at the same level as in Iceland,
eastern high Arctic Canada and Greenland.
Temporal comparisons
Seasonal variations
In a similar study of black guillemots in
Iceland, mercury concentration in pooled
liver samples of birds taken in March, May
and December in 1996 indicated a maxi-
mum mercury concentration in May at 0,9
mg/kg, descending in March to 0,7 mg/kg
with the lowest concentration in December
at 0,3 mg/kg ww (Gunnarsson et al., in
press). These findings correspond to find-
ings in the present Faroese material, where
the November pooled samples appeared to
be consistently low compared to the other
months (see Fig. 2).
Historical comparisons
The mercury concentration of museum
specimens of black guillemots from the
Faroe Islands has been studied (Somer,
1974; Appelquist, 1985). In these studies
the mercury analyses were done on pri-
maries and the results indicated increasing