Artificial reservoir V-17 (Old Swamp) was formed as a result of the construction of dams in 1952 and 1954 (MAYAK Production Association), located in a natural depression relief. Intermediate level liquid radioactive wastes (ILLW) have been discharged to this reservoir since 1949. The water surface area of the lake is 0.13 km2 with the volume of 0.36 Mm3. The maximum depth is 6.5 m with the average value of 2.8 m. Among c.a. 74 PBq deposited to the reservoir, the major portion is concentrated in the bottom sediments. Production Association "Mayak", Chelyabinsk region, Russia, - one of the largest nuclear facility in the Russian Federation.
Bottom sediments are playing the "geochemical barrier" role in the radionuclides migration processes. The radionuclides mobility/availability in bottom sediments depend on the bond strength and absorption mechanisms, which is determined by the radionuclides chemical properties, the state and forms of their presence in radioactive fallouts, the bottom sediments physicochemical features in absorbing complex particular mineralogical and chemical composition, etc. The aim of this study is to identify the 137Cs and 241Am chemical being forms in bottom sediments and reed of the reservoir V-17.
The following samples were collected: reservoir water, bottom sediments, reed (Phragmites australis). Plant samples have been washed out of the soil residues and sediments, air dried and divided into roots, stems and leaves. All samples were analyzed using gamma-spectrometry (Canberra GR 3818). The activity of 137Cs and 241Am in water, sediments and of reservoir-17 in "Mayak" territory were determined. For the sequential extraction, the following procedure was used: 1) Reservoir water imitated salts mixture (watersoluble) → 2) MgCl2 (exchangeable) → 3) NH4Ac (carbonates) → 4) NH2OH·HC (Fe-Mn oxides) → 5) 30%H2O2 (organic) → 6) HNO3 conc. (residue).
Results shows the total activity of 137Cs: (1.81 ± 0.06)·101 Bq/ml in water, (1.50 ± 0.01)·105 Bq/g in bottom sediments, (3.20 ± 0.04)·103 Bq/g in roots, (2.3 ± 0.1)·103 Bq/g in leaves, (7.9 ± 0.1)·102 Bq/g in stems. 241Am: (2.1 ± 0.1)·10-2 Bq/ml in water, (5.27 ± 0.05)·103 Bq/g in bottom sediments, (2.4 ± 0.3)·101 Bq/g in roots, (2.7 ± 0.7)·10-1 Bq/g in leaves, (5.0 ± 0.1)·10-2 Bq/g in stems. Maximum activity consider to bottom sediments and reed roots. Minimum activity was determined in water and reed leaves.