Bias in 238U decay chain members measured by γ-ray spectrometry due to 222Rn leakage.

In this work we investigate and quantify how effectively the noble gas 222Rn is trapped inside measurement beakers used in high-resolution gamma-ray spectrometry. We test six types of different beakers commonly utilized in γ spectrometry, including one novel construction, the γBeaker. We assessed 222Rn leakage by injecting 222Rn rich air into the examined beakers and investigated the abnormal decrease in 222Rn daughters - 214Pb and 214Bi. The measured decay times were used to estimate the 222Rn leakage. In addition, we investigated the influence of an additional beaker sealed with tape. However, the additional beaker sealing only slightly reduced the 222Rn escape and was not reproducible. Almost every tested beaker exhibited heavy 222Rn leakage. This may lead to an underestimation and radioactivity over-dispersion of 238U decay chain members when they are measured via their 222Rn daughter products.

210Pb, 137Cs and 7Be in the sediments of coastal lakes on the polish coast: Implications for sedimentary processes.

In this study we combined radioisotopes (210Pb, 137Cs and 7Be) and hydrodynamic modeling to investigate sedimentary processes in three coastal lakes on the Polish Baltic coast. The research aimed at establishing the depth of sediment mixing and its effects on sediment geochemistry as well as showing the relationship between lake water salinity and radionuclide distribution in the sediment cores. We established that the intensity of mixing displayed appreciable variability throughout the lakes and the thickness of sediment mixing layer was between <2 and 22 cm. The mixing was primarily due to wind-induced waves. The vertical mixing was shown to shift sulfidation of the sediments towards deeper layers. We found that the distributions of radioisotopes, 137Cs in particular, in the sediment cores from coastal lakes were strongly affected by the early diagenetic processes, which caused diffusive migration of radionuclides. The inventories of 210Pbex and 137Cs in the lakes were positively related to salinity. The high inventories of both isotopes (3.2-10.9 kBq ·m-2 for 210Pbex and 3.0-6.0 kBq·m-2 for 137Cs) in coastal lakes were explained by enhanced sedimentation within estuarine mixing zone and delivery of "additional" 210Pb and 137Cs to the lakes during saltwater ingressions. The results of this study have implications for the paleolimnology, sedimentology and biogeochemistry of coastal lakes.

Measurement of 137Cs in cultivated soils from two loess areas in Poland.

In this paper, a vertical distribution of 137Cs in agricultural soil was investigated. 137Cs is an anthropogenic radioisotope which is strongly adsorbed in soil and can be used to study soil erosion. This paper presents some preliminary results of measurements of activity of 137Cs in soil in Biala and Odonów areas. In both areas, the upper part of the soil profile was cultivated. The experimental results show that the vertical distribution of 137Cs in agricultural soil is different from the vertical distribution of 137Cs in undisturbed soil. The 137Cs is more uniformly distributed in the cultivated soil layer than in an undisturbed site. Migration of 137Cs below plough depth is limited. These data show that the depth distribution of 137Cs in soil profiles for cultivated fields should be considered for precise determination of soil erosion.