The influence of the soil grain size distribution on the 241Am migration in the soil profile | Влияние фракций гранулометрического состава на миграцию 241Am по профилю почвы
2010
Kudryashov, V.P., National Academy of Sciences (Belarus). Institute of Radiobiology | Tagaj, S.A., National Academy of Sciences (Belarus). Institute of Radiology
The grain size distribution of long-living Am241 (T sub (1/2) = 432.2) in 0-5 and 5-10 cm soil layers is discussed. The investigation has been carried in a former agricultural land with sod-podzol sandy soil located near the biggest flooding – Borschevka pond within the evacuation zone territory around the Chernobyl NPP. The sampling sites conventionally correspond to various soil moisture regimes: P-1 is a regular flooded soil, P-2 is intermittently flooded soil, P-3 is a dry valley. The division of each soil layer into grain size fractions of 1,0-0,5 mm; 0,5-0,25 mm; 0,25-0,1 mm; less than 0,1 mm was carried out by sieve analysis with water washing. The Am241 content of soil fractions was determined using the method of gamma-spectrometry by the low-energy radiation (E sub(upsilon) = 59.5 keV). The results have shown the increased contribution of a fraction less than 0,1 mm to the Am241 accumulation with depth. The soil moistening at regular and intermittent flooding influences the migration processes and promotes the secondary Am241 redistribution between 0,50-0,25 and 0,25-0,10 mm grain size fractions. The influence of the hydrological regime in the sampling sites is much more sharply defined by the Am241 activity distribution in the soil grain size fractions, than by the grain size fractions distribution by weight. Therefore, the possibility of gamma spectrometric determination of Am241 allows its using as an indicator of migration processes in soil for long-term radioecological monitoring of the unique evacuation zone territory around the Chernobyl NPP.
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