Geoscience Reference
In-Depth Information
Case study 4.1 Organic toxins in sediments: Baltic Sea
Discharges of chlorinated organic materials from paper and pulp mills (PPMs) have attracted a
great deal of attention in Sweden and many parts of the world (Södergren 1992). This section
will give a sedimentological angle to this important environmental problem. Case Fig. 4.1a illus-
trates the geographical distribution pattern of EOCl in surficial (0 -1 cm) sediment samples from
accumulation areas, and Case Fig. 4.1b shows how extractable organically bound chlorines
(EOCl) in sediment samples co-vary with two very important and specific toxins - dioxins and
furans. Other features are evident from Case Fig. 4.1a.
1
There is a large-scale spread of EOCl in this water system, the Baltic. The larger the emissions,
the larger the impact areas and the greater the potential ecological problems. The distribution
of EOCl in surficial sediments shows a very characteristic pattern, with high concentrations
close to the PPMs along the coast.
(c)
Dioxin
Furan
(b)
EOCl
7000
2000
1800
1600
1400
1200
1000
800
600
400
200
0
Coastal area with
high contamination
Area of diffuse
influence
6000
Dioxins (pg g
−
1
org)
Furans (pg g
−
1
org)
EOCl (
5000
g g
−
1
org)
µ
(a)
4000
3000
Coastal
jet-zone
2000
1000
0
0 5 10 15 20 25 30 35
Distance from Iggesund (km)
EOCl
in surficial sediments
from A areas in
µ
g g
−
1
LOI
(d)
1000
500
250
100
50
0
8 cores and 38 surface samples
0
1985
−
2
−
4
1970
~1950
~1930
−
6
−
8
−
10
−
12
−
14
−
16
−
18
Baltic proper
−
20
0 2 4 6 8 10 12 14 16 18 20
EOCl (
µ
g g
−
1
dw)
Case Fig. 4.1
(a) Distribution of EOCl in surficial A-area sediments in the Baltic. (b) The relationship between EOCl, dioxins
and furanes in surficial A-area sediments taken at different distances from the Iggesund paper and pulp mill in the Bothnian Sea.
(c) Illustration of the coastal jet-zone and the major hydrological flow pattern in the Bothnian Bay and the Bothnian Sea. (d) The
historical development of EOCl in the Baltic (based on eight sediment cores and 38 surficial sediment samples). (From Jonsson
1992; Håkanson 1999.)
