520
Land-Ocean Svstems in the Siberian Arctic: Dynamics and History
2
WO
i I :M jl Pb-2tO CX.
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ace. oogltt [glc:m2)
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PM 9451-7
PM9-l62-1
PM 9463-8
PM <)481 -2
PM 9-182-1
Figure 4: Activities of 210Pb 1ot • 210Pbex and 214Bi are plotted against compaction-corrected depth . On the plots
on the right the 2lOPb ex activities are presented on a logarithmical scale.
J... :
decay constant of 210Pb [0.031 a-I]
p :
dry bulk density [g cm- 3 ]
R:
mean accumulation rate [g cm- 2 a- l ]
S :
mean sedimentation rate [em a-I]
The mean accumulation rates [g cm- 2 a-I] , the average dry bulk densities (pers. comm.
Kassens, 1995), and the sedimentation rates [em a-I] of the investigated cores are listed in
Table 3. The sediment cores PM 9441-4 and PM 9451-7 could not be dated because we did not
find any 210Pb ex at all. This lack of 210Pbcx could be ascribed either to dilution with sediments
accumulating at a very high rate or to conditions preventing accumulation of recent sediment.
The sandy composition of these sediments suggests possible export of the fine grain fraction.
However, bioturbative mixing of 210Pb at the sediment water interface may distort the profiles