Fróðskaparrit - 01.01.2009, Page 174

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CHEMICAL SEDIMENT VARIABLES FROM THE FAROE AREA:
ORGANIC CONTENT, NITROGEN, PHOSPHORUS, ZINC, AND COPPER
fect when compared to untreated samples.
In un-sieved samples it is reasonable to ex-
pect a high content of large, non-organic
particles to influence the result, as well as
large numbers of small tube dwelling worms
(e.g„ Myriochele sp. and Phoronida sp.) or just
a few specimens of large bodied animals (e.g.,
Arctica islandica). Seaweed would also in-
fluence the result. Sieving eliminates the vari-
ability of samples and makes comparison re-
sults more reliable. There is no information
on any sieving of the sediment before analy-
sis by other authors so it is reasonable to ex-
pect the analyses to be done on untreated
sediments.
Some of the sites in this study are re-
peatedly sampled. There are a few replicates.
some are sampled more than once a year
and many are sampled about yearly. In such
cases, it should be possible to get a crude
chemical picture of the natural variance at
the site. Comparison between sites should
therefore be done with caution, especially
because there is so little information about
the samples and sampling procedures.
The stability of organic content
(LOI values)
One of the interesting questions this study
could help answer is how stable or change-
able is the organic content in the upper lay-
ers of the seabed. Is it constant at the same
site or does the organic content change tem-
porarily according to sources of organic
input?
Due to various reasons, it is diflicult to
collect sufficient quality data on organic
content from the same site over a long pe-
riod of time. In Table 12, all available data
from two of the stations from Skálafjørður,
SK05 and SK07 are shown. SK05 is in the
middle of the fjord at the deepest part at a
depth of about 67 m and SK07 about 2 km
north of SK05. Both are soft bottom locali-
ties. The data from these two stations are
from untreated samples.
There are 24 samples from SK05 and 13
from SK07 (Bloch et al„ 1986; Gaard, 1990;
Hoydal and Dam, 2004 and Johansen, 2006).
In 1985 and 1987, several samples were taken
during the summer period (no replicates). In
1997, three replicates were analyzed from
SK05 and, in 2005, two replicates. In the years
2000, 2001 and 2003, one single sample was
analyzed at each site.
The overall lowest value from SK05 was
5.5 % and the highest was 13.9 %. At station