Former uranium mining activities have led to the presence of naturally occurring nuclides embedded in soil. Such activities have also modified the secular equilibrium between radionuclides in 238U decay series. The objective of this paper is to quantify the long-term effect of former uranium mining activities on the behavior of the final radionuclide in the 238U-series, i.e. polonium-210 (210Po), present in soils. Soil samples are extracted from two uranium sites in France, specifically a quarried site and a natural site. The polonium distribution is studied within the various soil fractions, namely: water soluble, exchangeable, bound to carbonates, bound to iron/manganese oxides, bound to organic matter, and residual. 210Po is mainly found in the residual fraction of both study sites (87–90%), followed by the carbonates fraction (5–9%). The 210Po activity in the other fractions is very small in comparison with total activity.
Vision is an important sense for the majority of the wildlife species, affecting their ability to find food and escape predation. Currently, no study on radiation induced cataract frequency on the fish eyes lens has been done. However, any thorough future study of this subject will require more accurate dose estimates for the fish eye lens than those currently available. For this purpose, the eye lens absorbed dose per unit fluence conversion coefficients for electron irradiation were calculated using the MCNPX Monte Carlo radiation transport code package. All results were validated against three different fish voxel models. The discrepancies between model results mainly originate from the different fish eye dimensions used in the different studies and in two of the cases the lack of a defined eye lens region.
The dose conversion coefficients calculated in this work can be used to estimate the dose to the fish eye lens based on the activity concentration of the surrounding water. The model developed in this work has also demonstrated that the mathematical models still have several advantages over the voxel models.
Cave 222Rn has been a major health issue and subject of scientific debate for decades. While the basics of natural ventilation physics are well understood, it is difficult to make blind predictions of 222Rn concentrations in a given cave due to the complexity of cave systems. In-situ continuous observation is necessary to improve our ability to quantify radiation dose exposure and reduce radiation hazard to cave users, and trace the air exchange patterns occurring in caves. In this study, continuous monitoring using a RAD7 radon detector revealed high 222Rn concentrations and large fluctuations in 222Rn concentration in a small karst cave in southwest China, Shawan Cave. From August 2016 to July 2017, the average annual concentration was 47,419 Bqm−3 and ranged between 3720 and 123,000 Bqm−3, with lower values during summer than other seasons. Taking Shawan Cave as a case study, we suggest a framework to evaluate the potential dose exposure, allowing cave users to minimize risk of exposure to hazardous levels of 222Rn. Furthermore, we comparing results from this study with other studies in 35 caves worldwide, and conclude that there are three patterns of seasonal 222Rn variation. They were classified into five types of ventilation mode based on diversity of cave locations, geometry and connectivity of bed rock fracture networks, together with temperature differences between outside atmosphere and cave air.
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