Fróðskaparrit - 01.01.2009, Blaðsíða 182

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CHEMICAL SEDIMENT VARIABLES FROM THE FAROE AREA:
ORCANIC CONTENT, NITROGEN, PHOSPHORUS, ZINC, AND COPPER
and 11-47 mg/kg dry matter in deeper wa-
ters.
From seabed environmental surveys
from the Shetland side of the Faroe-Shetland
Channel, Environmental & Resource Tech-
nology, Ltd (2000) gave an overview of
chemical sediment variables before and after
drilling operations from a number of sites
used for exploration drilling for hydrocar-
bons. The data from the surveys before any
drilling showed organic contents between
0.13 to 5.36 %, zinc values from 8-88 mg/kg
and copper values from 2-35 mg/kg. These
values are within the same concentration
range as found in the offshore data from the
Faroe area.
From a survey off the Norwegian coast
(Vøring Plateau), at depths between 591-
1520 m in a region from Trondheim in the
south to Bodø in the north, Jensen et al.
(1999) found values of organic content, zinc
andcopper in thesedimentsfrom 4.0 to 14.7
%, 22.7-78.8 mg/kg and 6.4-38.0 mg/kg, re-
spectively. The copper concentration is very
similar to the Faroese offshore area, but the
zinc concentration is a bit higher and more
like the values found in Faroese inshore sed-
iments. Organic content on the Vøring
Plateau is relatively high and is comparable
to the high end values found in Faroese in-
shore waters.
Mannvik et al. (2002) summarize a re-
gional environmental seabed survey in the
Norwegian sector of the North Sea ( 58-60°
N and 1-2° W) at water depths around 100
m. In total, 230 sediment samples were ana-
lyzed, but 22 of these were described as re-
gional and reference stations and showed
very low levels of organic content, compared
to all other referenced areas. The organic
content was between 0.63 and 2.57 %, while
zinc and copper had values between 0.9-9.3
mg/kg and 0.6-2.1 mg/kg, respectively.
Botnen et al. (1992) found highly vari-
able concentrations of organic matter in sed-
iments from Norwegian inshore sediments.
The sediments were described as fine sands
to clay with LOI values from 6.75 to 26.50 %.
The maximum value was from a sample that
contained a large amount of decaying sea-
weed and is a good example of the impor-
tance of homogenization by sieving before
analysis. Otherwise the sediment values were
comparable to the values found in Faroese
inshore waters.
From the examples mentioned above, it
may be concluded that chemical variable