No abstract

Coal-fly-ash is one of the major byproducts of coal-based power plant in which naturally occurring radioactive materials (NORMs) are drastically enriched compared to those of feed coals. Thus, improper management of fly-ash may introduce additional radioactivity to the surrounding environment and cause radiological risk. So, in order to study the distribution of radionuclides in soil around a coal-based power plant and to evaluate their radiological risk, soil, coal and fly-ash samples were analyzed by using a HPGe detector for U-238, Ra-226, Th-232 and K-40 radioactivity concentrations. Furthermore, soil minerals were also studied by X-ray diffractometer to assess the mineralogical provenance of the radionuclides. Mean radioactivity concentrations (in Bq·kg−1) of U-238, Ra-226, Th-232 and K-40 in soil samples are 102.9±41.4, 63.6±7.4, 103.4±13.9 and 494.2±107.5, respectively which are comparatively higher than the typical world mean value. Elevated levels of radioactivity are likely due to the presence of illite, kaolinite, monazite, rutile and zircon minerals in the soil samples rather than technogenic contributions from the power plant. Furthermore, mean soil contamination factor (CF) are close to unity and mean pollution load index (PLI) is below unity while the average radium equivalent activity (Raeq in Bq·kg−1), external hazard index (Hex), absorbed γ dose rate (D in nGyh−1), annual effective dose rate (E in mSv·y−1) and excess lifetime cancer risk (ELCR in Sv−1) are 249.5±21.7, 0.67±0.06, 114.2±9.4, 0.20±0.02, 4.9×10−4±0.4×10−4, respectively, which are within the permissible limit. Thus, in terms of radioactivity concentrations and associated environmental and radiological indices, the effect of the power plant is insignificant.

The original version of this article unfortunately contained an error in equaton 1. The denominator ε of equation 1 was missing. The corrected equation 1 is shown below. A ¼ cps sample −cps BG ε Â I γ The original article has been corrected.

No abstract

Strontium-90 ( 90 Sr) and cesium-137 ( 137 Cs) were released from the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in March 2011. Strontium-90 concentration in environment was extremely lower than that of 137 Cs in the soil after the FDNPP accident. However, 90 Sr may induce higher risk of health effect to human than 137 Cs by considering longer biological half-life of 90 Sr than 137 Cs. Moreover, there is not sufficient data on 90 Sr horizontal and vertical distribution compared to 137 Cs, which is important for predicting their long-term migration.In the present study, the distribution of 90 Sr and 137 Cs in the soils of Kawauchi and Fukushima paddy rice fields was investigated and the migration of 90 Sr and 137 Cs in Lake Ogi sediment and its forestry catchment area was studied. A rough relation between 90 Sr and 137 Cs levels in soil is shown and such insufficient correlation might be defined by the low 90 Sr concentration and because of global fallout. Furthermore, 90 Sr gave higher coefficient of variation in comparison to 137 Cs, portraying that the movement of 90 Sr is more affected by the environmental factors rather than 137 Cs. The depth dependency of 90 Sr and 137 Cs in Lake Ogi forestry catchment area is shown for both radionuclides, and the activity concentration decreases with the increase of depth. However, the 90 Sr infiltrates more to 10 cm soil profile in contrast to 137 Cs, showing 90 Sr faster vertical migration than 137 Cs. Sediment to soil ratio for 90 Sr reported a higher value than that of 137 Cs, which possibly depicts more horizontal flowing of 90 Sr from forest soil to lake sediment than 137 Cs. Consequently, the higher mobility of 90 Sr than 137 Cs was proposed.