84
vivianite. P043 diffused into the oxic bottom water would be adsorbed by fresh
formed Fe oxide.
E
q.J
r0
20
40
60
8O
0
[
W
Main River
2
4
6
8
10
2
4
6
8
10
0
20
:I
80/
0
,eliver
0
4
8
12 16 20
0
2
4
6
8
10
Fig. 4.42, The contents of organic carbon (.Corg, %) in the sediments of major rivers.
Fig. 4.43 shows distribution of Cu between sediments and porewater in the
sediments of major rivers. In the Rhine River sediments (Wesel), particulate Cu
decreased from 430 mg/kg at 80 cm depth to 120 mg/kg at 50 cm depth. As reported
by F6rstner and Miiller (1974), high concentrations of Cu in the deeper sediments
(below 50 cm depth) can be attributed to the industrial activities before 1970. In the
Elbe River sediments (Hamburg), a decrease of Cu concentrations occurred at 15 cm
depth. Lowest concentrations of particulate Cu (69-88 mg/kg) were found in the
Weser River sediments (Bremen).
Porewater Cu showed a different tendency. In the Weser River, dissolved Cu
decreased from 75 nM in the bottom water to 5.4 nM at 64 cm depth. Similar profiles
are also found in the Elbe River and the Main River. In Rhine River, where the