shown on Fig. 17.9 (Gulin et al. 2002; Polikarpov et al. 2008). Inventories of
137 Cs
in bottom sediments at the selected sites of the NW-W part of the Black Sea
(Stokozov 2004; Polikarpov et al. 2008) are shown on Fig. 17.10. The most
contaminated bottom sediments were in the delta of the Danube and the DnieperBug estuary. This reflected the relatively large entrance of the Chernobyl
137 Cs with
flow of the north-western rivers into the Black Sea for a 4–8 year period that has
elapsed since the Chernobyl NPP accident to the moment of sampling. The
increased concentrations of
137 Cs were found, also, at Cape Tarkhankut, in the
north-western part of the Crimean peninsula. This could be the result of active
irrigation of this region of the Dnieper water entering the North-Crimean Canal
(NCC). It is known, that the annual consumption of water in the NCC is about
9.5 km
3 , which is comparable, for example, with the annual runoff of the Dniester
River. It should also be noted that the components of irrigated land ecosystems
accumulated up to 65–70% of the
137 Cs activity, entering to the NCC.
In addition, the increased concentration of
137 Cs in the surface layer of bottom
sediments of the area may be related to the sedimentation of suspended matter at the
circulation of water masses along the coast with a complex shoreline. Thus,
sedimentation of the terrigenous suspended matters in estuarine areas was very
high, and the sedimentation flow of the deposition of the radionuclides in these
areas of the sea could be main factor of self-purification of water.
Thus, the general regularity of the change of cumulative
137 Cs in bottom
sediments of the Black Sea after the ChNPP accident was that the maximum
stock of this radionuclide was found in estuarine areas of the Danube and the
Dnieper Rivers and it was an order of magnitude higher than those in the
tiefensprung of the northwestern part near the isobath of 100 m and in two orders
Table 17.4 Indicators of large-scale circulation of water oxygen and hydrogen sulphide zone of
the Black Sea
Oxygen zone
Interval
depths,
m
The surface area
of the lower
boundary zone,
km
2
Volume,
km
3
Water exchange
with the underlying
layers
Period of water
exchange Т exch.
through the lower
boundary, years
m/
year
Т exch. , km
3 /
year
0–200
423,000
71,110
10–35 3120–10,920 6.5–23.0
5050.1
a
14.1
a
Hydrogen-sulphidous zones
Interval
depths,m
The surface area
of the upper
boundary zone,
km
2
Volume,
km
3
Water exchange
with the water of the
oxidizing layer
Period of water
exchange Т exch. hydrogen-sulphidous zone,
years
m/
year
km
3
/year
200–2212 312,000
475,890
10–35 3120–10,920 43.0–152.0
5051
a
94.2
a
a
– estimate obtained by the results of simulation (Egorov et al. 1993); T exch. – period of water
exchange
288
N.Y. Mirzoyeva et al.
137 Cs
in bottom sediments at the selected sites of the NW-W part of the Black Sea
(Stokozov 2004; Polikarpov et al. 2008) are shown on Fig. 17.10. The most
contaminated bottom sediments were in the delta of the Danube and the DnieperBug estuary. This reflected the relatively large entrance of the Chernobyl
137 Cs with
flow of the north-western rivers into the Black Sea for a 4–8 year period that has
elapsed since the Chernobyl NPP accident to the moment of sampling. The
increased concentrations of
137 Cs were found, also, at Cape Tarkhankut, in the
north-western part of the Crimean peninsula. This could be the result of active
irrigation of this region of the Dnieper water entering the North-Crimean Canal
(NCC). It is known, that the annual consumption of water in the NCC is about
9.5 km
3 , which is comparable, for example, with the annual runoff of the Dniester
River. It should also be noted that the components of irrigated land ecosystems
accumulated up to 65–70% of the
137 Cs activity, entering to the NCC.
In addition, the increased concentration of
137 Cs in the surface layer of bottom
sediments of the area may be related to the sedimentation of suspended matter at the
circulation of water masses along the coast with a complex shoreline. Thus,
sedimentation of the terrigenous suspended matters in estuarine areas was very
high, and the sedimentation flow of the deposition of the radionuclides in these
areas of the sea could be main factor of self-purification of water.
Thus, the general regularity of the change of cumulative
137 Cs in bottom
sediments of the Black Sea after the ChNPP accident was that the maximum
stock of this radionuclide was found in estuarine areas of the Danube and the
Dnieper Rivers and it was an order of magnitude higher than those in the
tiefensprung of the northwestern part near the isobath of 100 m and in two orders
Table 17.4 Indicators of large-scale circulation of water oxygen and hydrogen sulphide zone of
the Black Sea
Oxygen zone
Interval
depths,
m
The surface area
of the lower
boundary zone,
km
2
Volume,
km
3
Water exchange
with the underlying
layers
Period of water
exchange Т exch.
through the lower
boundary, years
m/
year
Т exch. , km
3 /
year
0–200
423,000
71,110
10–35 3120–10,920 6.5–23.0
5050.1
a
14.1
a
Hydrogen-sulphidous zones
Interval
depths,m
The surface area
of the upper
boundary zone,
km
2
Volume,
km
3
Water exchange
with the water of the
oxidizing layer
Period of water
exchange Т exch. hydrogen-sulphidous zone,
years
m/
year
km
3
/year
200–2212 312,000
475,890
10–35 3120–10,920 43.0–152.0
5051
a
94.2
a
a
– estimate obtained by the results of simulation (Egorov et al. 1993); T exch. – period of water
exchange
288
N.Y. Mirzoyeva et al.