ISSN 10674136, Russian Journal of Ecology, 2015, Vol. 46, No. 3, pp. 299–302. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © L.M. Shaposhnikova, I.I. Shuktomova, 2015, published in Ekologiya, 2015, No. 3, pp. 237–240.
Vast areas all over the world are contaminated every
year with natural radionuclides (NRN) as a result of
mining and processing of uranium ores and raw
hydrocarbons. According to collateral data, no less
t of oil and gas production waste with
increased NRN contents has been stored on the terri
tory of Russia (Kurilenko and Khaikovich, 2004).
Since radioactive contamination of the environment is
progressing, the search for optimal decontamination
and remediation methods remains a high priority.
Methods for decontamination and remediation of
radioactively contaminated areas develop in different
directions. One of them concerns mechanical meth
ods involving excavation of radioactive soil layer and
its subsequent burial or covering with clean material.
Such an earthfill method was used for decontamina
tion of the monazite sand mining and processing facil
ity in Ozernaya, 60 km from Yekaterinburg (Trapezni
kov et al., 1977) in 1994 and the former radium pro
duction site in the Ukhta district of the Komi Republic
The purpose of this study was to evaluate the long
term consequences of decontamination by an earthfill
method in sites contaminated by the radium industry
in 1931 to 1957 and the role of different plant species
in processes leading to NRN redistribution in soils.
is in the floodplain of the Chut’ and
Ukhta rivers. It was contaminated with stratal waters
dumped after radium extraction onto the surface of
soddy meadow soil. In 1962, this site was partially bur
ied under a layer of sand–gravel mixture (SGM) with
the initial contents of radium, uranium, and thorium
of 0.02 Bq/g, 6.0 mBq/g, and 20 mBq/g, respectively
(Gruzdev et al., 1971). The vegetation of the site con
sists of mixed meadow herbage.
is 8 km from the village of
Vodnyi. A large part of this site (about 1 ha) was con
taminated as a result of solid waste dumping. This area
is covered by a pine–birch–spruce forest of dwarf
shrub–moss type growing on technogenic podzolic
Samples for analysis were collected in a grid pat
tern, at 10m intervals, in 1981 and 2002. To evaluate
radionuclide uptake and accumulation in the above
ground phytomass, plant samples were taken from
m plots with different densities of soil contami
nation with radium. Uranium in ashed samples was
determined by the luminescence method with NaF
crystals (Dobrolyubskaya, 1962); radium, by the radon
emanation method (Starik, 1969); and thorium, by
the colorimetric method with Arsenazo III, after
removing impurities with KU2 cation exchange resin
(Kuznetsov and Savvin, 1961).
We evaluated the longterm dynamics of radionu
clide contents and distribution in the soil–plant cover
of the radium site, separately in decontaminated and
untreated areas. In the former, the 05 cm layer corre
sponds to organogenic horizon A
, and the 5–30 cm
layer, to the SGM cover over the buried soil. Today, the
content of radium in the soil profile (ashed samples)
varies from 0.01 to 80 Bq/g; of uranium, from 0.5 to
823 mBq/g; and of thorium, from 0.4 to 77.9 mBq/g.
In the untreated area, radium is accumulated
mainly in the upper soil layers, with a peak in the A
horizon (Fig. 1a). In the decontaminated area, its
concentrations are the highest in the 0–55 cm layer.
The initial amount of this radionuclide in the
untreated area decreased with time in the upper part of
the soil profile but increased in its lower part. In the
decontaminated area, its increase was observed in the
upper soil layers: the average radium content in the
SGM reached 1.13 Bq/g by 1981 and 2.27 Bq/g by
2002, which is almost equal to that in the 0–55 cm soil
layer in the untreated area (2.42 Bq/g).
In decontaminated soil, the content of uranium in
the upper soil layers is lower than in the buried soil
(Fig. 1b). Its value in the SGM layer averages
15.4 mBq/g, exceeding the initial value by a factor of 2.5.
The highest content of this element in the untreated
soil is characteristic of the A
horizon, where it has
slightly accumulated with time.
The content of thorium in the untreated soil
reaches a maximum in the upper layers. The pattern of
Consequences of Radioactive Decontamination by Earthfill Method
in a Former Radium Production Site
L. M. Shaposhnikova and I. I. Shuktomova
Institute of Biology, Komi Scientific Center, Kommunisticheskaya ul. 28, Syktyvkar, 167982 Russia
Received June 10, 2014