Fróðskaparrit - 01.07.2004, Blaðsíða 105

KYKSILVUR í FØROYUM - EIN GJØGNUMGONGD AV TØKUM DÁTUM
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Sample location- and year Pb Hg Cd Cu Zn Dry Organic Source Depth
Pg/kg weight, carbon,
dw % weight %*
Skeivibanki, 4,78 0,122 26,4 37,2 63,3 0,61 Magnusson et al. 0-2 cm
61.41.50 N-07.47.2 W, 350mdepth, 1991 1996
Skeivibanki, 7,3 <60 0,15 59,3 86,8 63 0,58 TOC Stange et al. 1996 0-1 cm
61.39 N-07.50 W, 347 m depth, 1994
Sandoyarbanki 61.51 N, 05.44 W, 8 Olsen et al. 2003 0-1 cm
330 m depth, 2000 Føroyabanki, outer areas, 6,73 10 0,19 10,85 22,50 Gaard and nd
197-254 mdepth, 1992 Poulsen 1992
Føroyabanki, towards 2,44 4 0,22 5,60 2,38 Gaard and nd
themiddle, 104-127 mdepth, Poulsen 1992
1992
#: Organic carbon in weight percent of dw. Possible loss on ignition as weight percent of dw.
: Depth of analysed sedimenl core (nd = not analysed).
Table 8. Heavy metals in sediments from some banks. Values are in mg/kg dw when otherwise not stated.
(Adapted from Mikkelsen et al., 2002)
6 and Table 8. It is noticed that the concen-
tration of mercury in the Skálafjord is ap-
prox. 10 times as high as on the Sando-
yarbanka. A better basis for comparison
arises if the mercury concentrations are ex-
pressed on an organic carbon or organic
matter content basis. The organic matter
content is often analysed as loss on ignition
(LOI), but this parameter is not known for
the Sandoyarbanka samples. Such data are
available though for samples from other
banks, and a LOI of 0,6 % may be used as
an approximate value. Using the assumed
LOI it may be estimated using the equation
for the regression line from the fjord sedi-
ments (Fig. 4) that a corresponding mer-
cury concentration at LOI = 0,6% would be
0,006 mg/kg. The measured Sandoyarban-
ka mean mercury concentration was 0,008
mg/kg in the top segments of the cores,
which is fairly close to the value calculated
from the assumed LOI, also when taken
into consideration that the mercury concen-
trations in question were close to the detec-
tion limit of the analyses laboratory and
thus that the analysis error may be relative-
ly large.
On the shelfedge
As part of the preparations for the oil ex-
ploration in Faroese water, 20 sediment
samples were collected in 1999 along the
southeastem part of Faroese shelf on the
slope towards the Faro-Shetland Channel,
and at one station on the western part of the
slope at similar latituđes. The samples were
taken at between 275 and 517 meters depth,
and were analysed for mercury as well as