Fróðskaparrit - 01.07.2004, Page 93

KYKSILVUR í FØROYUM - EIN GJØGNUMGONGD AV TØKUM DÁTUM
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Fig. 1. Mercury in soil profiles from
Norðuri á Fossum, 2002.
(Heilsufrøðiliga Stan’sstovan,
unpubl.
In 2002 two soil profiles were collected
at Norðuri á Fossum. The soil profiles were
cut in segments of 1,5 cm starting at 1 cm
below the surface, and analysed for mer-
cury as well as a selection of other metals
(Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V
and Zn) as well as the dry matter content
(Heilsufrøðiliga Starvsstovan). The results
of the mercury analyses are given in (Fig.
1) as a function of the upper level of profile
segment depth. There are significant differ-
ences in the inercury concentrations among
the two profiles even though they were tak-
en only approx. 50 m apart in an area that is
not influenced by local pollution sources.
The profile no. 3 was taken from the east-
ern side of the river Dalá, in an area where
deptli segment,
Sampling cm Hg
Norðuri á Fossum, no. 3, peat 1-9 0,54
Norðuri á Fossum, no. 6, peat 1-9 0,23
Reference sitea 0-20 0,15
Heilsufrøðiliga Starvsstovan, 1991
Table 1 Mercury (mg/kg dw) in peat cores taken
Norðuri á Fossum in 2002 and at a reference site in
1991.
regular wet deposition collection has been
ongoing since 1996. The profile no. 6 was
taken from the western side of Dalá, in a
moist and bog-like area. The soil from the
two sites have not been characterised apart
from the metal analyses indicated in the
parenthesis above. When comparing medi-
ans of metal concentrations in the two pro-
files, it appears that there are three metals
which are markedly different in the profile
no. 3 compared to no. 6, they are mercury,
vanadium and arsenium, where the two fist
mentioned are elevated and the last men-
tioned is lowered. The median mercury
concentration in the profile no. 3 is more
than twice as high as the one in the profile
from the more moist area. In the surface
layer (-1 to 2,5 cm) , the concentration of
mercury in the profiles no. 3 and 6 are 0,90
and 0,48 mg/kg dw respectively. The tran-
sition from organic soil to mineral soil oc-
curred at a depth of approx. 6 cm in the pro-
file no. 3. Diagenetic processes may relo-
cate metal-ions in a sediment or moist soil
environment. The process is driven by re-
dox-reactions and it is known that man-