title: Anthropogenic radionuclide fluxes and distribution in bottom sediments of the cooling basin of the Ignalina Nuclear Power Plant.
abstract: Based on γ-ray emitting artificial radionuclide spectrometric measurements, an assessment of areal and vertical distribution of (137)Cs, (60)Co and (54)Mn activity concentrations in bottom sediments of Lake Drūkšiai was performed. Samples of bottom sediments from seven monitoring stations within the cooling basin were collected in 1988-1996 and 2007-2010 (in July-August). For radionuclide areal distribution analysis, samples from the surface 0-5 cm layer were used. Multi sample cores sliced 2 cm, 3 cm or 5 cm thick were used to study the vertical distribution of radionuclides. The lowest (137)Cs activity concentrations were obtained for two stations that were situated close to channels with radionuclide discharges, but with sediments that had a significantly smaller fraction of organic matter related to finest particles and consequently smaller radionuclide retention potential. The (137)Cs activity concentration was distributed quite evenly in the bottom sediments from other investigated monitoring stations. The highest (137)Cs activity concentrations in the bottom sediments of Lake Drūkšiai were measured in the period of 1988-1989; in 1990, the (137)Cs activity concentrations slightly decreased and they varied insignificantly over the investigation period. The obtained (238)Pu/(239,240)Pu activity ratio values in the bottom sediments of Lake Drūkšiai represented radioactive pollution with plutonium from nuclear weapon tests. Higher (60)Co and (54)Mn activity concentrations were observed in the monitoring stations that were close to the impact zones of the technical water outlet channel and industrial rain drainage system channel. (60)Co and (54)Mn activity concentrations in the bottom sediments of Lake Drūkšiai significantly decreased when operations at both INPP reactor units were stopped. The vertical distribution of radionuclides in bottom sediments revealed complicated sedimentation features, which may have been affected by a number of natural and anthropogenic factors resulting in mixing, resuspension and remobilization of sediments and radionuclides. The associated with particles (137)Cs flux was 129 Bq/(m(2) year). The (137)Cs transfer rate from water into bottom sediments was 14.3 year(-1) (or, the removal time was 25 days). The Kd value for (137)Cs in situ estimated from trap material was 80 m(3)/kg. The associated with particles (60)Co flux was 21 Bq/(m(2) year), when (60)Co activity concentration in sediment trap particles was 15.7 ± 5 Bq/kg. (60)Co activity concentration in soluble form was less than the minimum detectable activity (MDA = 1.3 Bq/m(3)). Then, the conservatively derived Kd value for (60)Co was >90 m(3)/kg.
authors: State Research Institute Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania. Electronic address: radeko@ar.fi.lt.
authors: D
authors: D
authors: Marčiulionienė
authors: State Research Institute Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania.
authors: J
authors: J
authors: Mažeika
authors: State Research Institute Center for Physical and Technological Sciences, Savanoriu av. 231, LT-02300 Vilnius, Lithuania.
authors: B
authors: B
authors: Lukšienė
authors: State Research Institute Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania.
authors: O
authors: O
authors: Jefanova
authors: State Research Institute Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania.
authors: R
authors: R
authors: Mikalauskienė
authors: State Research Institute Nature Research Centre, Akademijos str. 2, LT-08412 Vilnius, Lithuania.
authors: R
authors: R
authors: Paškauskas
mesh_terms: D019015:Geologic Sediments / Q000032:analysis*; D060106:Lakes / Q000032:analysis*; D008097:Lithuania; D055848:Nuclear Power Plants; D011834:Radiation Monitoring; D011868:Radioisotopes / Q000032:analysis*; D012621:Seasons; D014875:Water Pollutants, Radioactive / Q000032:analysis*
chemical_list: D011868:Radioisotopes; D014875:Water Pollutants, Radioactive
keywords: (137)Cs; (239,240)Pu; (54)Mn; (60)Co; Areal and vertical distribution; Bottom sediment