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 x/: 3.05 for spring, 1.25 x/: 3.78 for summer, 5.17 x/: 2.03 kBq m(-3) for autumn and 9.83 x/: 1.48 for winter on the ground floor; and 1.43 x/: 3.71 for spring, 0.168 x/: 2.49 for summer, 1.08 x/: 2.39 for autumn and 2.08 x/: 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.

. An air cleaner was installed in a room with elevated radon activity concentration, and the following parameters have been monitored: activity concentrations of 222 Rn (Rn) and its short-lived products (RnP), degree of equilibrium between Rn and RnP (F), fraction of unattached RnP (fun), and the number concentration and size distribution of aerosol particles (5–530 nm). Several hours of filtration removed the >10 nm particles almost completely, thus increasing the contribution of the <10 nm particles, associated with unattached RnP. Consequently, fun was substantially augmented with a concomitant decrease in F.

Spatial distribution of radioactive gasses thoron (Tn) and radon (Rn) in indoor air of 9 houses mostly during winter period of 2013 has been studied. According to properties of alpha decay of both elements, air ionization was also measured. Simultaneous continual measurements using three Rn/Tn and three air-ion active instruments deployed on to three different distances from the wall surface have shown various outcomes. It has turned out that Tn and air ions concentrations decrease with the distance increase, while Rn remained uniformly distributed. Exponential fittings function for Tn variation with distance was used for the diffusion length and constant as well as the exhalation rate determination. The obtained values were similar with experimental data reported in the literature. Concentrations of air ions were found to be in relation with Rn and obvious, but to a lesser extent, with Tn.

Concentration and size distribution of airborne particles (size range 10–1100nm), using a SMPS+C Scanning Mobility Particle Sizer, and concentrations of positive and negative cluster ions (size range 0.36–1.6nm), using several CDI-06 Gerdien-type integral air ion detectors, have been monitored in three rooms in rural dwellings of Serbia and Slovenia, during periods when nobody was present in the room and while smoking and heating were taking place. The highest particle generation rate was 2.4×1011min−1 while cigarette smoking was taking place and was 1.5×1011min−1 during heating with a cast iron stove with wood burning at 150°C, and 1.1×1010min−1, during heating with an Alpine-type oven at 40–50°C. The related particle loss rate constants were 0.0603min−1, 0.0442min−1, and 0.0067min−1. The estimated mean values of the effective ion attachment rate βeff vary between (2.2–5.4)10−6cm3s−1. A correlation between ions concentration and particles concentration and their sizes has been sought, and findings are discussed and shown.

V letih od 1998 do 2001 smo v zraku Postojnske jame na najnižji točki merili koncentracijo radona (CRn) in radonovih kratkoživih razpadnih produktov (CRnDP), ravnotežni faktor (F), delež nevezanih radonovih razpadnih produktov (fun), zračni tlak (P), relativno vlažnost zraka v jami (RH) in temperaturo zraka v jami (Tin) ter zunaj (Tout). Poseben poudarek je bil na fun in na njegovi odvisnosti od vremenskih razmer. Vrednosti fun so bile v širokem razponu, od 0,10 do 0,68. Z uporabo novega dozimetrijskega modela smo na osnovi izmerjenih vrednosti fun izračunali dozne pretvorbene faktorje in ugotovili, da so bili znatno višji od 5 mSv/WLM, to je vrednosti, ki jo priporoča metodologija ICRP-65. Tako so dejanske doze, ki jih prejmejo jamski vodiči, v povprečju za faktor 8 poleti in za faktor 2,7 pozimi višje od vrednosti, ki jih dobimo po dosedanji metodologiji ICRP-65.Short-term summer and winter monitoring was carried out at the lowest point in Postojna cave, on air concentrations on radon (CRn) and radon decay products (CRnDP), the equilibrium factor (F) and unattached fraction of radon decay products (f un ), barometric pressure (P), relative air humidity in the cave (RH) and air temperature outside (T out ) and in the cave (T in ), with the emphasis on f un . Dose conversion factors (DCF) for mouth and nasal breathing were calculated from the f un values (ranging from 0.10 to 0.68) and effective doses for the employees in the cave were obtained. These signifi cantly exceed the doses based on the ICRP-65 methodology now in use.

Increasing attention has been paid to radon in both Slovenia and Kazakhstan. The paper reviews their activities in radon measurements and dose estimates for radon exposure mitigation. Slovenia succeeded to accomplish the main goal of managing exposure to radon in homes and at workplaces at acceptably low levels, while in Kazakhstan there are still quite a number of dwellings with potential radon risk needing further monitoring and mitigation measures.

Soil radon (222Rn) has been monitored during winter months under cool-temperate deciduous stands of different surface geology in Tomakomai and in Sapporo, Hokkaido, Japan. Radon level was lower in Tomakomai of immature soil of porous volcanic ash emitted from an active volcano (Mt. Tarumae), compared with those in Sapporo of alluvial sediments. In Tomakomai, mean value of the 222Rn activity concentration was higher in winter (570 Bq m−3) than in summer (350 Bq m−3) at a depth of 1 m, which is consistent with the results in cold and dry winter reported in the literature. In contrast, soil radon decreasing with decreasing soil temperature from mid-September (5.0 kBq m−3) remained low (2.6 kBq m−3) under persistent snow in Sapporo, which had already been observed in the same location. Measurements of the activity concentrations of 222Rn in snow and in snow air as well as in soil air indicate that the small amount of 222Rn is released from the ground surface to the overlying snowpack with a 222Rn flux density of 0.4 mBq m−2 s−1 under thick snow cover in Sapporo.

Natural radioactivity is one of the essential components of the environment. Unlike the Sudety mountains area in Poland, the Tatra Mountains were not the subject of wide survey as regards the levels of natural radioactivity. Especially, the concentrations of radon (natural radioactive gas) have not been investigated there in terms of their possible negative health impact. Within the frame of bilateral cooperation between the Institute of Nuclear Physics in Krakow, Poland, and the Joef Stefan Institute in Ljubljana, Slovenia, the measurements of natural radioactive elements in old uranium mines in the Tatra National Park were performed in June 2010. The investigated sites were located in Dolina Biaego (The Valley of the White). One of the mines is situated near the tourist path. The paper presents the results of complex measurements of natural radioactivity in both uranium drifts. The concentration of radon gas inside the mining drifts exceeded 28,000Bqm(-3). Also, very high gamma dose rates were observed (up to 5600nSvh(-1)). The maximum concentrations of natural radioactive elements (potassium K-40, radium Ra-226, thorium Th-232) in rock samples amounted to 535, 2137, and 18Bqkg(-1), respectively. The effective dose rates due to radon and thoron inhalation have been assessed as 0.013mSvh(-1) (for the lowest concentration) and 0.121mSvh(-1) (for the highest concentration).

Depth distribution profiles of environmental radionuclides (137Cs and 210Pb) have been investigated in soil to elucidate the underlying environment of semi-natural temperate deciduous and/or coniferous forest soils in Slovenia (Žirovski vrh, Idrija, Kočevski Rog, Pohorie, Gorišnica and Rakitna). Surface enrichment of both nuclides was observed at all the sites investigated in this study, suggesting that the soils had undergone little natural or anthropogenic disturbance for at least the last several decades. Apparent annual burial rates of 137Cs (0.1–0.2 cm y−−1) were estimated to be about 1.3 times higher than those of 210Pb at individual sites of different lithology, which suggests strong affinity of 210Pb to soil organic matter. Variability of the vertical distribution profiles of these nuclides depends not only on “in situ” pedology but also on geographical and meteorological conditions, especially precipitation and wind direction.

Water samples were collected from 124 springs in Slovenia and analysed for tritium (3H). Tritium was enriched electrolytically and its concentration determined by liquid scintillation analysis. Tritium concentrations ranged from 325 to ca. 3000 Bq m–3, with a geometric mean of 1223 Bq m–3 and geometric standard deviation of 1.6. Although tritium concentrations in springs are generally low, they proved to be useful in qualitative assessment of recent recharge.

Carbon sources were estimated by measuring carbon isotope ratios (δ13C and Δ14C) with accelerator mass spectrometry (AMS) in forest soils of different lithology. Six locations were selected in temperate deciduous and coniferous stands in Slovenia (Žirovski vrh, Idrija, Kočevski Rog, Pohorje, Gorišnica, and Rakitna), where carbonate rocks consisting of limestone and dolomite are abundant as underlying bedrock. Carbon isotope fractionation would not have occurred in two carbonaceous soils, since the values of both δ13C and Δ14C changed consistently in these soils after thermal (550°C, 2 h) or chemical (1 M HCl, 24 h) treatments. Organic components were found to be predominant carbon sources (70–100%) in the uppermost portions (0–2 cm in depth). In deeper portions at a depth of about 30–35 cm, soil carbon may be derived completely from underlying carbonate minerals in Idria, western part of Slovenia. The Combination of heat and chemical treatments with AMS provides practical information on soil carbon sources in carbonaceous soils.

Anomalies have been observed in radon content in soil gas from three boreholes at the Orlica fault in the Krsko basin, Slovenia. To distinguish the anomalies caused by environmental parameters (air and soil temperature, barometric and soil air pressure, rainfall) from those resulting solely from seismic activity, the following approaches have been used. First, the seismic activity data were eliminated from the dataset and then an artificial neural network (ANN) with 5 inputs for environmental parameters and a single output (radon concentration) was trained with the standard backpropagation learning rule. Then the predictions of Rn concentrations (C-p) generated with this ANN for the whole dataset were compared to measurements (C-m) and three types of anomalies (CA - correct anomaly, FA - false anomaly and NA - no anomaly) have been detected in the signal vertical bar C-m/C-p - 1 vertical bar by varying five parameters describing an anomaly within predefined intervals. An exhaustive search among results was made to find the best ones and thus identifying the best set of parameters. Finally, an attempt was made to shorten the search procedure by training another ANN with numbers of anomalies of each type in the input and five anomaly detection parameters in the output. With these procedures we were able to correctly predict 10 seismic events out of 13 within the 2-year period. (C) 2009 Elsevier B.V. All rights reserved.

At Cazzaso (Friuli) in northeast Italy, radon (Rn-222) activity concentration in soil gas in a borehole at a depth of 80 cm has been monitored continuously (at a frequency of once an hour) since May 2004, using a Barasol probe (Algade, France). In addition, environmental parameters (air and soil temperature, barometric pressure) have been recorded. The results have been evaluated and the relationship between radon levels and seismic activity is discussed. Correlation between radon concentration and barometric pressure has been observed. Preliminary results have shown a distinct radon anomaly prior to some earthquakes.

The transport of radon (222Rn) from the ground towards the surface is influenced by a number of geophysical and geological parameters, among them seismicity. Prior to an earthquake, the formation of stress causes changes in the strain field. The displacement of rock mass within the earth’s crust before an earthquake leads to changes in gas transport from deep layers in the earth to the surface [5]. As a result, larger quantities of radon are released from the pores and fractures of the rocks towards the surface. This may be considered as an anomaly in the concentration of radon. Because of seismicity, changes in underground fluid flow may account for anomalous changes in concentration of radon and its progeny [8]. A small change in velocity of gas [6] into or out of the ground causes a significant change in radon concentration at shallow soil depth as changes in gas flow disturb the strong radon concentration gradient existing between the soil and the atmosphere. A small change in gas flow velocity causes a significant change in radon concentration. Thus, monitoring of radon in soil gas is a means of detecting changes related to an earthquake. For small earthquakes, it is often impossible to identify an anomaly caused by a seismic event and not by meteorological or hydrological events. Therefore, the implementation of more advanced statistical methods in data evaluation appears to be essential [1, 3, 7]. In this contribution, the 32-month time series of radon concentration together with the environmental parameters (air and soil temperature, barometric presIdentification of radon anomalies in soil gas using decision trees and neural networks Boris Zmazek, Saso Džeroski, Drago Torkar, Janja Vaupotic, Ivan Kobal

Radon ((222)Rn) activity concentration in outdoor air was measured by exposing track etch detectors at 60 points. Values were found in the range of 3.7-41.0 Bq.m(-3), with a geometric mean (GM) of 11.8 Bq.m(-3) and geometric standard deviation (GSD) of 2.2. An outdoor radon map of Slovenia was drawn, showing the majority of elevated values to be in the south-west part of the country that is covered by carbonates.

The Ravne tectonic fault in north-west (NW) Slovenia is one of the faults in this region, responsible for the elevated seismic activity at the Italian-Slovene border. Five measurement profiles were fixed in the vicinity of the Ravne fault, four of them were perpendicular and one parallel to the fault. At 18 points along these profiles the following measurements have been carried out: radon activity concentration in soil gas, radon exhalation rate from ground, soil permeability and gamma dose rate. The radon measurements were carried out using the AlphaGuard equipment, and GammaTracer was applied for gamma dose rate measurements. The ranges of the obtained results are as follows: 0.9–32.9 kBq m−3 for radon concentration (CRn), 1.1–41.9 mBq m−2 s−1 for radon exhalation rate (ERn), 0.5–7.4×10-13 m2 for soil permeability, and 86–138 nSv h−1 for gamma dose rate. The concentrations of 222Rn in soil gas were found to be lower than the average for Slovenia. Because the deformation zones differ not only in the direction perpendicular to the fault but also along it, the behaviour of either CRn or ERn at different profiles differ markedly. The study is planned to be continued with measurements being carried out at a number of additional points.

Radon (222Rn) and carbon dioxide were monitored simultaneously in soil air under a cool-temperate deciduous stand on the campus of Hokkaido University, Sapporo, Japan. Both 222Rn and CO2 concentrations in soil air varied with atmospheric (soil) temperature in three seasons, except for winter when the temperature in soil air remained constant at 2–3°C at depth of 80 cm. In winter, the gaseous components were influenced by low-pressure region passing through the observation site when the ground surface was covered with snow of ~1 m thickness. Carbon isotopic analyses of CO2 suggested that CO2 in soil air may result from mixing of atmospheric air and soil components of different origins, i.e. CO2 from contemporary soil organic matter and old carbon from deeper source, to varying degrees, depending on seasonal meteorological and thus biological conditions.

Radon (Rn-222) and thoron (Rn-220) were surveyed in indoor air of 15 public buildings and 10 homes in Slovenia in November 2004 by exposing Rn-Tn discriminative etched track detectors. The following ranges of the activity concentration were obtained for public buildings: 98-2680 Bq m(-3) for C-Rn, 19-1330 Bq m(-3) for C-Tn and 0.11-0.72 for the C-Tn/C-Rn ratio. In homes, the C-Rn range was 12-374 Bq m(-3) and all C-Tn values, except one of 29 Bq m(-3), were below the detection limit of 10 Bq m-3. Monthly effective doses in public buildings due to Rn (E-Rn) and Tn (E-Tn) were in the ranges 0.05-1.45 mSv and 0.01-0.47 mSv, respectively, and in homes, 0.018-0.548 and 0.009-0.095 mSv, respectively. The E-Tn/E-Rn ratio in public buildings was in the range 0.07-0.47.