Tadeusz A. Przylibski

Estimating the radon emanation coefficient from crystalline rocks into groundwater

A simple method is proposed to estimate the coefficient of radon emanation from crystalline rocks into underground waters. In these cases, the crystalline rock seems as both the source and the reservoir of the radon. The calculations are based on a formula proposed by Maché for determining the concentration of radon in underground waters. Due to the inaccuracy of estimating some parameters (e.g. porosity), the results have a significant error. The advantage of this method is its simplicity and the possibility of obtaining results in a relatively short time. The estimated values of the emanation coefficient for selected crystalline rocks of the Sudety Mountains (SW Poland) vary from 7 to 41%, and after considering the error resulting from the estimation of rock porosity, saturation and density, the values range from 5 to 60%. The highest values of emanation coefficient (41, 33 and 21%) have been obtained for rocks in areas of tectonic dislocations and the lowest ones are for rocks outside dislocation zones (9 and 7%). The calculations imply that the emanation coefficient of rocks may have a greater influence on radon concentration in underground waters than the contents of radium in the reservoir rocks.

Radon and its daughter products behaviour in the air of an underground tourist route in the former arsenic and gold mine in Złoty Stok (Sudety Mountains, SW Poland).

This paper describes the occurrence of radon and its daughter products in the accessible workings, partially open to the public, in the former arsenic and gold mine in Zloty Stok. The geology of the area and the characteristics of the workings provide the background for explanation of the genesis of radon and its daughter products and of the spatial and temporal variations in their concentrations. The results demonstrate that well-ventilated areas along the tourist route have the lowest values of all the measured parameters and that temporal variations of these parameters are irregular. The highest concentration values for radon (up to 18.50kBq/m3) and its daughter products (up to 14.49kBq/m3) have been recorded in the workings with obstructed natural ventilation. These are the areas where seasonal oscillations in the concentrations of these isotopes have been registered, with the maxima in summer and the minima in winter. These sections of the workings are inaccessible to the casual visitor. Radon is supplied to the workings from the side walls and its concentration is influenced, most of all, by ventilation and the degree of rock fissuring. The reason is the uniform and not very high content of 226Ra in the rocks where the galleries were excavated. Only locally, in the workings of the Gertruda adit lying outside the tourist route, do open fault zones have significant influence on enhanced concentrations of radon and its daughter products. These fault zones constitute effective routes of radon migration to the workings. In spite of this, it must be stated that neither guides nor tourists are exposed to excessive concentrations of radon or its daughter products in the tourist route area. However, the extension of the route to other workings will require the introduction of forced ventilation in order to lower theconcentration of radon and its daughter products. reserved.

Correction factors for determination of annual average radon concentration in dwellings of Poland resulting from seasonal variability of indoor radon.

The method for the calculation of correction factors is presented, which can be used for the assessment of the mean annual radon concentration on the basis of 1-month or 3-month indoor measurements. Annual radon concentration is an essential value for the determination of the annual dose due to radon inhalation. The measurements have been carried out in 132 houses in Poland over a period of one year. The passive method of track detectors with CR-39 foil was applied. Four thermal-precipitation regions in Poland were established and correction factors were calculated for each region, separately for houses with and without basements.

Origin of radon in medicinal waters of Lądek Zdrój (Sudety Mountains, SW Poland)

In this paper the origin of radon in the underground medicinal waters Lądek Zdroj is presented. This health resort is situated in the Polish part of the Sudety Mountains. The concentration of radon in these waters (exploited by five springs and one bore hole) range from 122 to 1284 Bq/dm3, whereas the concentration of radium does not exceed 6.8 Bq/dm3. In gneisses, through which the exploited waters flow, the amount of radium reaches about 34 Bq/kg and only locally rises to 50 Bq/kg. The increased concentration of 222Rn in the medicinal waters of Lądek Zdroj is not influenced by the time of contact of these underground waters with the rocks through which they flow. The concentration of 222Rn also does not depend on the concentration of 226Ra which is dissolved in these waters. Radon is dissolved as a gas in underground waters in the zone of their outflow to the surface. It is caused by the increase in the emanation coefficient of rocks in the weathering zone and in dislocation zones, through which the waters outflow to the surface. To a smaller extent, the genesis of radon in the thermal waters of Lądek Zdroj could also be related to a small admixture of shallow circulation waters containing enhanced amounts of dissolved radon. Much higher concentrations of radon in one of the intakes (Jerzy) should be attributed to its location in the area of a fork of a big dislocation zone and the increased quantity of 226Ra in gneisses of the intake region.

222Rn concentration changes in medicinal groundwaters of Lądek Zdrój (Sudety Mountains, SW Poland)

Abstract Lądek Zdroj in southwestern Poland is a place where thermal groundwaters, regarded as medicinal, outflow. They contain, amongst other characteristic parameters, enhanced quantities of 222 Rn , which is dissolved in these waters in the area of their outflow to the surface. Distinct fluctuations in its concentrations with time (from 35 to 55%) are characterised by irregularity and vary for particular intakes, showing a non-changing trend (Dąbrowka intake), a falling trend (Chrobry, Sklodowska-Curie, L-2 intakes) or a growing trend (Jerzy and Wojciech intakes) in the last several tens of years, although the waters are of the same hydrochemical type and flow out of the same hydrogeological structure. There is no seasonal variation in 222 Rn concentrations in these waters except in the Jerzy intake, where a 6-month cycle was observed in the years 1970–1971. However, the fluctuation amplitude was insignificant in comparison to those of the irregular fluctuations. It seems that the changes in 222 Rn concentrations in the thermal groundwaters of Lądek Zdroj may be caused by atmospheric factors, such as temperature, pressure, humidity and by the discharge of the intakes.

RADON IN WATERS FROM HEALTH RESORTS OF THE SUDETY MOUNTAINS (SW POLAND)

Abstract This paper discusses the geological background related to the presence of selected radon waters in the Sudety Mountains. Special attention is paid to radon waters whose chemical composition is formed within metamorphic rocks (mainly gneisses). The physical, chemical, and isotopic characteristics of the waters of L↓ek Zdroj, Czerniawa Zdroj and Świeradow Zdroj are presented. The rocks at these locations are briefly characterized by their U, Th, and Ra contents. It was found that the basic role in enrichment of these waters with radon is played by the 100 m deep near-surface zone. This is related to the increased emanation coefficient in this zone as a consequence of weathering processes. It is also shown that the residence time of water in the rocks is not important for radon genesis.

Radon-222 and 226Ra concentrations in mineralized groundwaters of GorzanÓw (Kłodzko Basin, Sudeten Mountains, SW Poland)

This work characterizes the occurrence of radionuclides 222Rn and 226Ra in the mineralized groundwaters of Gorzanów. The village is situated in the Sudeten Mountains, which are known in Poland for having increased concentrations of the aforesaid radionuclides in their groundwaters. However, in Gorzanów, the measured concentrations of 226Ra were low both in the reservoir rocks and mineralized waters. Consequently, the 222Rn concentration in the groundwaters also turned out to be low. The 226Ra content of these waters should mainly be associated with the dissolution of this nuclide, together with other main ions, at large depths, at slightly enhanced temperature. Radon-222, on the other hand, penetrates into the water during its outflow to the surface, in the zones of intensive friable deformations near fault zones. Thus, in the groundwaters of Gorzanów, the concentrations of these nuclides, subsequent in the uranium series, do not have a common genesis and they are not correlated with each other.

Mean annual 222Rn concentration in homes located in different geological regions of Poland – first approach to whole country area

The paper presents the results of year-long measurements of radon ((222)Rn) concentration inside 129 buildings in Poland in relation to the geological conditions of their foundation. The authors took into account the division of the country into tectonic units, as well as the lithology of the rocks forming the bedrock of these buildings. As expected, the highest value of mean annual (222)Rn concentration (845 Bq/m(3)) was recorded in a building situated in the area of the Sudetes, while the highest geometric mean (characteristic of the expected log-normal data distribution) was calculated based on measurements from buildings located within the East-European craton, in the area of Mazury-Podlasie monocline, where it reached 231 Bq/m(3). Such results reflect geological conditions - the occurrence of crystalline rocks (especially U- and Ra-enriched granites and orthogneisses) on the surface in the Sudetes, and of young post-glacial sediments containing fragments of Scandinavian crystalline rocks, also enriched with U and Ra, in the area of Mazury-Podlasie monocline. However, the least expected result of the investigations was finding out that, contrary to the hitherto widespread belief, none of the major tectonic units of Poland can be excluded from the list of those containing buildings with mean annual (222)Rn concentration exceeding 200 Bq/m(3). The mean annual concentration of radon for all the buildings were much higher than the mean concentration value (49.1 Bq/m(3)) of indoor radon in Poland quoted so far. These results cast a completely new light on the necessity to perform measurements of radon concentration in residential buildings in Poland, no more with reference to small areas with outcrops of crystalline rocks (especially the Sudetes, being the Polish fragment of the European Variscan belt), but for all the major tectonic units within Poland.

New chemical and physical data on keilite from the Zakłodzie enstatite achondrite

Abstract Keilite, (Fe,Mn,Mg,Ca,Cr)S, from the Zakłodzie enstatite achondrite is described. Forming xenomorphic grains up to 0.5 mm in diameter, the keilite is associated with troilite (or pyrrhotite), Fe-Ni metal, an (Fe,Zn,Mn)S phase, enstatite (with relict forsterite in cores), plagioclase and accessory schreibersite, oldhamite, graphite, sinoite, and an SiO2 polymorph. It is brittle and possesses a good cleavage similar to that of galena, parallel to (001), (010), and (100). X-ray diffraction structural data reveal the following: cubic space group Fm3m, α = β = γ = 90°, a = 5.1717 (18) Å, unit-cell volume V = 138.32 (8) Å3; D = 3.958 g/cm3; Z = 4. The chemical formula based on 63 electron microprobe point analyses is: (Fe0.437, Mn0.356, Mg0.160, Ca0.017, Cr0.019, Zn0.001)S1.008. Compared with previously described keilites from enstatite chondrites, the Zakłodzie keilite is richer in (Mn,Ca,Cr)S and poorer in the Fe- and Mg-end-members and, consequently, it is nearer to alabandite and oldhamite. This is the first detailed description of keilite from a meteorite that is not an enstatite chondrite.

222Rn and 226Ra activity concentrations in groundwaters of southern Poland: new data and selected genetic relations

Since 2008, the authors have been conducting research into 222Rn and 226Ra activity concentrations in shallow circulation groundwaters in southern Poland. Measurements have been performed with a liquid-scintillation method and ultra low-level liquid-scintillation spectrometers α/β Quantulus 1220. The research carried out so far has demonstrated that in the Sudetes groundwaters with high activity concentrations of 222Rn and 226Ra are common. In other studied areas in southern Poland no shallow circulation groundwaters with high radon or radium concentrations have been found yet. The conducted research has demonstrated that the activity concentration of 222Rn dissolved in shallow circulation groundwaters in the Sudetes depends chiefly on the amount of radon, which after being released as gas from reservoir rocks is dissolved in waters flowing through these rocks. At the same time, the concentration of 222Rn dissolved in some shallow circulation groundwaters in the Carpathians is influenced significantly by the amount of radon produced from the decay of its parent ion 226Ra2+ dissolved in these waters.