Abstract We show that the Late Triassic–Early Jurassic continental Arctic experienced wintertime freezing conditions, despite the exceptionally high atmospheric CO 2 levels, by quantifying common lake ice-rafted debris (L-IRD) identified in the Junggar Basin of Xinjian, NW China. This L-IRD consists of outsized (0.1–12 mm) lithic clasts ‘floating’ in otherwise fine-grained, profundal lake sediment matrix. Laser-diffraction grain-size analysis demonstrates that the grain-size distribution for lacustrine strata of Junggar Basin is very similar to modern sediments from the seasonally ice-covered Sea of Okhotsk, reflecting a similar depositional mechanism. Three-dimensional computed tomography and two-dimensional thin sections demonstrate that the outsized clasts are dispersed, rather than confined to sand lenses or layers. These results are inconsistent with alternative methods of bimodal sediment deposition such as mud flows, algae rafting or root rafting. The discovery of Triassic–Jurassic continental freezing provides new context for understanding global climate during periods with high-CO 2 conditions and climate and biotic changes in the Mesozoic Era.

Abstract Three major problems in cave micrometeorology are analysed: the concept of the temperature of a cave and its phenomenology; the internal energy flows and consequent local entropy production; and a non-hydrostatic physical model of the underground convective air circulation. A cave’s temperature is rich in information, but it is often difficult to obtain because it requires experimental accuracies to be pushed beyond the reach of common external meteorological instruments to detect a variety of factors, such as thermal sedimentation, seasonal variations and the effects of external morphology. Energy flow has an essential role in estimating the sensitivity of a cave to external inputs. A model for evaluating the local entropy production is developed. Entropy seems to be the most basic parameter, explaining both the sensitivity of the environment and its tendency to form complex structures. Analysis of the second-order terms of convective air circulation is more complex than expected; nevertheless, only such an analysis is able to explain the behaviours (e.g. continuity in the airflow) that cannot be predicted by the first-order models.

Abstract Year-long continuous radon monitoring was carried out (using Sarad Radon Scout devices) in a dwelling with high radon levels in the karst region of Slovenia. Two living rooms were selected: one on the ground floor with normal housework activities; and the second, on the first floor, closed and unattended. Meteorological data were also recorded. The following seasonal geometric means of radon activity concentration (kBq m −3 ) have been found: 6.28 ×/: 3.05 for spring, 1.25 ×/: 3.78 for summer, 5.17 ×/: 2.03 kBq m −3 for autumn and 9.83 ×/: 1.48 for winter on the ground floor; and 1.43 ×/: 3.71 for spring, 0.168 ×/: 2.49 for summer, 1.08 ×/: 2.39 for autumn and 2.08 ×/: 2.14 for winter on the first floor. Results are supported by additional radon measurements in other rooms; and in water the results indicate a strong radon source associated with an underground karst shaft.

Abstract This paper presents selected issues related to the use of 222 Rn in therapeutic treatments. Radon is a radioactive element whose usage in medicine for more than 100 years is based on the radiation hormesis theory. However, owing to the radioactive character of this element and the fact that its alpha-radioactive decay is the source of other radionuclides, its therapeutic application has been raising serious doubts. The author points to potential sources and carriers of radon in the environment that could supply radon for use in a variety of therapies. Except for centuries-long tradition of using radon groundwaters, and later also the air in caves and underground workings, the author would also like to focus on soil air, which is still underestimated as a source of radon. The text presents different methods of obtaining this radioactive gas from groundwaters, the air in caves, mining galleries and soil air, and it presents new possibilities in this field. The author also discusses problems related to the transportation and storage of radon obtained from the environment. Within radon-prone areas, it is often necessary to de-radon groundwaters that are intended for human consumption and household usage. Also, dry radon wells are used to prevent radon migration from the ground into residential buildings. The author proposes using radon released from radon groundwaters and amassed in dry radon wells for radonotherapy treatments. Thanks to this, it is possible to reduce the cost of radiological protection of people within radon-prone areas while still exploiting the 222 Rn obtained for a variety of therapies. With regard to the ongoing and still unsettled dispute concerning the beneficial or detrimental impact of radon on the human organism, the author puts special emphasis on the necessity of strictly monitoring both the activity concentration of 222 Rn in media used for therapeutic treatments and of its radioactive decay products. Monitoring should be also extended to the environments in which such treatments are delivered (inhalatoriums, baths, saunas, showers, pools and other facilities), as well as to the patients – during and after the radonotherapy treatments. It is also essential to monitor the dose of radon and its daughters that is received by persons undergoing radon therapy. This should facilitate the assessment of the effectiveness of these treatments, which may contribute to a fuller understanding of the mechanisms of radon impact, and ionizing radiation in general, on the human organism. This will make it easier to ultimately confirm or reject the radiation hormesis theory. It is also essential to monitor the effective dose that is received by medical and technical staff employed to deliver the radonotherapy treatments.

Abstract: Petroleum systems represent complex multiphase subsurface environments. The properties of the noble gases as conservative physical tracers allow them to be used to gain insight into the physical behaviour occurring within hydrocarbon systems. This can be used to better understand the mechanisms of hydrocarbon migration, residence time of fluids, and measurement of the scale of the subsurface fluid system involved in the transport and trapping of the hydrocarbon phase. The noble gases in the subsurface derive from different sources with distinct isotopic compositions, allowing them to be resolved in any crustal fluid. We discuss the processes within petroleum systems that incorporate the noble gases from each of these sources into hydrocarbon accumulations. The dominant mechanism controlling the introduction of air-derived noble gases into petroleum systems is via subsurface groundwater, and this records key information about the interaction of the petroleum system with the hydrogeological regime. Radiogenic noble gases accumulate over time, recording information about the age and relative timing of processes within the petroleum system. We review the conceptual framework and quantitative models describing these processes using examples from previous studies, and discuss both their current limitations and the potential for their application to unconventional hydrocarbon systems.