Fróðskaparrit - 01.07.2004, Síða 78

76
MERCURY IN LIVER, EGGS AND FEATHER OF BLACK GUILLEMOT
CEPPHUS GRYLLE FAEROENSISIN THE FAROE ISLANDS
ther sample preparation. The target number
of eggs from each location was 10, but on
Skúvoy in 1999 and 2000, the sample size
was 8 and 9 eggs respectively.
Chemical analyses of metals were done
using AAS (FIMS 400 amalgam system,
Perkin Elmer AA600 or cold vapour AAS)
or ICP-MS at commercial laboratories
which could provide accredited analyses or
at a laboratory with similar quality control.
Results
Liver
Fig. 1 shows the mercury concentration in
liver from black guillemots taken in two pe-
riods during 1996 and 1997. The results are
given for adult males and females and for
juveniles of both sexes. The light bars rep-
resent pooled sample results whereas the
dark bars represent individually analysed
birds. Because the variability in the Janu-
ary/February 1997 data is not known, it is
not possible to determine whether the ap-
parent differences between the two periods
for the adult male group is real or merely a
sampling artefact. Pooled sample analyses
of mercury in adult male livers were made
for August 1997 (Fig. 2) also, theresults in-
dicate that this may be the time of year with
maximum mercury concentration in the
adult male liver whereas there appears to be
a low concentration in November, Fig. 2.
Generalisation from these data in terms of
influence of parameters like age and sex on
the mercury concentration should be done
with care as the individual variability in the
data is not quantified for every group, and
generalisation in terms of temporal trends
is also restricted by lack of continuous data.
Nonetheless, the individual analyses of a
subset of 33 specimens indicate that there
are large individual variations in going
B.guillemot
□ Jan/Feb'97
□ Jun/Aug'96
Fig. I. Mercury in black guillemot livers. Tlte samples taken in January and February 1997 were analysed in
pools, whereas data from June/August 1996 refers to individual analyses, except the one forjuvenile males, tliat
was analysed as one pool and where the sampling was actually done in April/June 1996. The number of
individuals represented by each bar is in the order ofappearance from left to right: 8;5;14;4;5;6;18;4. Adapted
from Dam, 1998b, Dam, 2000 and Olsen et al., 2003.