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The research was aimed at providing new knowledge in the field of chemical characteristics of solid waste generated in the process of combustion of sewage sludge in fluidized bed furnaces. The research material consisted of disposed fluidized beds (DFB), sewage sludge ash (SSA) and air pollution control residues (APC) from three Polish installations for the thermal treatment of sewage sludge. Natural radionuclides as well as anthropogenic isotope 137Cs were determined in the tested materials and the migration of a wide spectrum of trace elements to various waste fractions generated in the process of sewage sludge combustion was examined. It was observed that both radioisotopes and most of the trace elements determined accumulate in SSA and DFB, while the APC fraction contains a much smaller amount of them. The exceptions are mercury and selenium, whose volatile compounds migrate to the exhaust gas dedusting system and accumulate in the APC fraction (up to 40 mg/kg and 13 mg/kg, respectively). A potential threat from the 226Ra isotope in SSA is identified in the context of the management of this waste in the production of building materials because the typical activity of 226Ra in SSA collected from areas with very low Ra content in natural environment exceeds 1.5-6 times the activity of this isotope in conventional cement mixtures. When managing SSA and DFB, special attention should be paid to the content of metalloids such as As, B and Se, due to the high content of mobile forms of these elements in the mentioned materials.

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From early April 2020, wildfires raged in the highly contaminated areas around the Chernobyl nuclear power plant (CNPP), Ukraine. For about 4 weeks, the fires spread around and into the Chernobyl exclusion zone (CEZ) and came within a few kilometers of both the CNPP and radioactive waste storage facilities. Wildfires occurred on several occasions throughout the month of April. They were extinguished, but weather conditions and the spread of fires by airborne embers and smoldering fires led to new fires starting at different locations of the CEZ. The forest fires were only completely under control at the beginning of May, thanks to the tireless and incessant work of the firefighters and a period of sustained precipitation. In total, 0.7-1.2 TBq 137Cs were released into the atmosphere. Smoke plumes partly spread south and west and contributed to the detection of airborne 137Cs over the Ukrainian territory and as far away as Western Europe. The increase in airborne 137Cs ranged from several hundred µBq·m-3 in northern Ukraine to trace levels of a few µBq·m-3 or even within the usual background level in other European countries. Dispersion modeling determined the plume arrival time and was helpful in the assessment of the possible increase in airborne 137Cs concentrations in Europe. Detections of airborne 90Sr (emission estimate 345-612 GBq) and Pu (up to 75 GBq, mostly 241Pu) were reported from the CEZ. Americium-241 represented only 1.4% of the total source term corresponding to the studied anthropogenic radionuclides but would have contributed up to 80% of the inhalation dose.

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The measurements of the specific activity of natural radioactive isotopes of radium (226Ra), thorium (232Th) and potassium (40K) in chosen samples of imported (China, Finland, Spain, India, Sweden) and Polish (Izerski, Karkonosze, Siedlimowicki, Strzegomski, Strzelinski) granites were performed. The measurements were carried out with 2 × 2" NaI(Tl) scintillation detector. The measured specific activity on natural radioactive isotopes were within the following ranges: 5.8-312 [Bq kg-1], 5.5-189 [Bq kg-1] and 109-1590 [Bq kg-1] for 226Ra, 232Th and 40K, respectively. Obtained concentrations of radioactive isotopes allowed to perform the analysis of the exposure of the humans from the ionizing radiation emitted by the granites. The determination of the exposure consisted in the calculation of absorbed gamma dose rate (D) [nGy h-1] for each sample, which fell in the range between 20 and 511 [nGy h-1], annual effective dose rate (AED) [mSv year-1] ranging between 0.10 and 2.50 [mSv year-1], radium equivalent activity (Raeq) [Bq kg-1] with values between 22 and 570 [Bq kg-1], external and internal hazard indices (Hex) and (Hin) falling in the ranges 0.06-1.53 and 0.08-2.41 respectively, as well as gamma (Iγ) and alpha (Iα), representative level indices with values 0.08-2.0 and 0.029-1.56, respectively. Moreover, obtained results were compared with the international standard values given by the European Commission (EC), the United Nations Scientific Committee on the Effects of Atomic Radiation given in UNSCEAR Reports, and the results of research from other laboratories.

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This paper reports evidence of Pu isotopes in the lower part of the troposphere of Central Europe. The data were obtained based on atmospheric aerosol fraction samples collected from four places in three countries (participating in the informal European network known as the Ring of Five (Ro5)) forming a cell with a surface area of about 200,000km(2). We compared our original data sets from Krakow (Poland, 1990-2007) and Bialystok (Poland, 1991-2007) with the results from two other locations, Prague (Czech Republic; 1997-2004) and Braunschweig (Germany; 1990-2003) to find time evolution of the Pu isotopes. The levels of the activity concentration for (238)Pu and for ((239+240))Pu were estimated to be a few and some tens of nBqm(-3), respectively. However, we also noted some results were much higher (even about 70 times higher) than the average concentration of (238)Pu in the atmosphere. The achieved complex data sets were used to test a new approach to the problem of solving mixing isotopic traces from various sources (here up to three) in one sample. Results of our model, supported by mesoscale atmospheric circulation parameters, suggest that Pu from nuclear weapon accidents or tests and nuclear burnt-up fuel are present in the air.

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