Fróðskaparrit - 01.07.2004, Side 100

98
MERCURY IN THE FAROE ISLANDS — A REVIEW OF AVAILABLE DATA
vágsvatn and Leynavatn is available trough
the NorLake project (Landkildehus, 2002)
and inspection of the pH values for the two
waters show that these are exactly the same
(pH= 6,7) and thus a differences in pH-val-
ues which has been suggested as possible
explanation for different mercury concen-
trations in sediments due to the impact of
pH on metal-complexation processes
(AMAP, 1998) is obviously not a contribut-
ing element. It is reasonable to assume that
the aforementioned binding to organic ma-
terial is the dominating vector. The water
chemistry indicates that the difference in
organic material in the sediments is mir-
rored in the water column, where signifi-
cantly higher concentrations of nutrients
are found in Sørvágsvatn than in Leynavatn
(Jensen, 2002). In Sørvágsvatn, the concen-
tration of nitrate is 10 times higher than in
Leynavatn, total nitrogen is twice as high,
and total phosphorus is also higher, at 3 g
P/1 and 5gP/l respectively.
Results from analyses of sediments from
lakes in northern Finland are similar to re-
sults from lakes in the Faroes with regard to
the shape of the profile of mercury concen-
tration vs. time. Mercury concentrations in
sediments from lake Nitsijárvi were about
100 pg/kg approx. 200 years ago and have
increased to about 200 pg/kg in 1988. Ex-
cept from transient reductions occurring
about 1850 and 1950 the mercury concen-
trations have been gradually increasing
(Mannio et al., 1997).
Terrestrial mammals
Hare, Lepus timidus, have been analysed
for heavy metals (Hg, Cd and Se) in sam-
ples from 1997 and 1999 (Olsen et al.,
2003). The mercury results are given in
Table 5.
Compared to hares in northern parts of
Norway (Kálás et al., 1995) where the mer-
cury concentration in liver from young
hares and adult hares were 0,0065 mg/kg
and 0,016 mg/kg respectively, the mercury
concentration in the Faroese hares are high-
N Lenght, cm Weight, kg dw, g/lOOg Hg
9 Hare '97 i 3,3 28,60 0,07
9 Hare '99 3 71 (14,6) 3,0 (0,30) 24,27 (0,63) 0,06 (0,05)
9 Hare '99* 6 23,89 0,05
crHare '97 1 3,2 25,70 0,07
cHare '99 3 78 (3,5) 2,9 (0,30) 24,87 (0,18) 0,04 (0,02)
cHare '99* 5 0,03
Juvenile '97 1 2,4 25,90 0,10
Juvenile '99 3 74 (2,1) 2,3 (0,05) 24,16(1,77) 0,05 (0,04)
Juvenile '99* 6 23,68 0,06
Juvenile '99* 6 23,53 0,07
* Pooled sample Table 5 Mercury in hare livers, mg/kg ww. Mean values are given as well as slandard deviations in parentheses.
(Olsen et al., 2003).