Geoscience Reference
In-Depth Information
(a)
G , MBq/m 2
H , m
(b)
MBq/m 2
12
2.2
10
2.0
10
5
2
1
0.05
1
8
1.6
2
6
1.2
R. Techa
4
0.8
2
0.4
100 m
0
0
Y , m
0 5 10 15 20 25
Q , GBq/km
W , m
(c)
Case Fig. 3.3 (a) Caesium-137 distribution on the
Techa floodplain. Note the high concentration of
137 Cs-contaminated sediment close to the channel.
(b) Caesium-137 deposition ( G ) and bank height ( H ) above
water level as a function of the distance from the channel ( Y ).
Deposition in this 'transit zone' area is confined to the
near-channel area by the steep valley sides. (c) Caesium-137
contaminant distribution along the River Techa, where Q is
the total 137 Cs deposition per unit river length and W is the
width of the contaminated floodplain. (Adapted from
Chesnokov et al. 2000.)
1200
400
Q ( x )
W ( x )
900
300
600
200
300
100
0
0 4 8 12 16
X , km
away from the river, 137 Cs concentrations decline significantly, generally within 15-20 m from
the river (Case Fig. 3.3c). Even though these depositional sites concentrate highly contaminated
sediment, they only constitute a small percentage of the total 137 Cs within the surveyed area and
are thus referred to as 'transit zones'.
A large proportion of 137 Cs-contaminated sediment is deposited in 'sedimentation zones'
that comprise a well-drained floodplain with large meanders to the east of the Muslomovo and
a marshy floodplain (with a gradient of 0.0003 and width of 700 m) to the west of the village.
The latter contains more than 2 TBq of 137 Cs. The total deposition of 137 Cs-contaminated
sediment per unit length of the River Techa corresponds well to the contaminated floodplain
width distribution along the river (Case Fig. 3.3b), showing that the floodplain is a very effective
contaminant sink, and that low-lying, wide floodplain areas such as those discussed above store
large amounts of 137 Cs.
Relevant reading
Chesnokov, A.V., Govorun, A.P., Linnik, V.G., et al. (2000) 137 Cs contamination of the Techa river flood plain
near the village of Muslumovo. Journal of Environmental Radioactivity 50 , 179 -91.
Trapeznikov, A.V., Pozolotina, V.N., Chebotina, M.Ta., et al. (1993) Radioactive contamination of the Techa
river, the Urals. Health Physics 65 , 481- 8.
Search WWH ::




Custom Search