Glaciers are decaying due to global warming. Svalbard is a very sensitive area within the European High Arctic and studies on glacier changes and evolutions are representative for the Arctic. The present work aims glaciers at Spitsbergen; we investigated meltwater supplied by glacierized basins in introducing radioactive isotope measurements in combination with classical parameters. Among the natural radioactive elements, the most promising is the noble gas radon, more precisely the isotope 222Rn, with a short half life of 3.8 days and the possibility of automated continuous measurements. Measurements of radon in glacier meltwater showed surprisingly high concentrations thus enabling investigations with radon as valuable tracer. Only meltwater in contact with rock or sediments has the possibility to be charged with radon. Varying radon concentrations can be linked to changes in mixing meltwater from different origins, roughly the surface of glaciers (supraglacial), within (englacial) and under ice (subglacial). We are able to collect information on the glacier drainage system and its evolution over time and thus contribute to the study of glacier dynamics. Results from three sampling periods on Werenskioldbreen glacier, covering different glaciological seasons, are presented and discussed in this study. The potential results of further continuous measurements will give supplementary information on drainage footpaths and the style and system of the draining of glaciers. Our study intends also a better understanding of the response of glaciers to environmental parameters and, on a longer term, to make a contribution to climate change studies.
Desorption of radon is of short duration but longer than telluric noises and is usually accomplished in less than one minute based on our binary event counting with a 16 second interval. Adapting an hourly counting time schedule, telluric noises as well as transient variation of radon anomalies of a few hours duration can be excluded but not the spike-like anomalies of a few minutes duration. The time series of soil gas radon, as recorded continuously in a redesigned ditch located inside an active fault zone, has sporadic spike-like anomalies. The anomalies could represent desorbed radon from shallow sources as observed from a similar detecting system located near a construction site. Radon release due to compressive stress is related to compressive back-filling activities. Spike-like anomalies, on the other hand, are related to caisson auguring shear activities. Charge transfer related to electrokinetic potential phenomena may have resulted in the sudden radon releases and caused spike-like anomalies. The timing of the anomalies provides good information on the timing of electokinetic potential change as a result of outward propagation of stress from hypocenter. With multiple monitoring stations, the location, timing, and magnitude of the incoming earthquake can then be calculated or graphically derived.
Radon in soil gas had been measured at 39 locations, distributed along three prominent lineaments in the Guwahati city, Assam, India; using solid state nuclear track detectors. The most suitable site is selected from these locations, for continuous radon monitoring by an Alpha-GUARD PQ 2000 on the basis of high average radon concentration, no rock structure in the background and low ground water level even in the rainy season in summer. Influences of ambient temperature, atmospheric air pressure and relative humidity on temporal variation of radon concentration are investigated applying multiple regression method and an equation is derived. Using this equation, radon anomaly peaks are selected and a possible link between these and the observed earthquakes (data collected from USGS and Regional Research Laboratory, Jorhat, Assam, India) have been suggested.
Radon activity concentrations measurements in some Jurassic caves of Poland are presented. The aim is to estimate the radiation doses to casual visitors, cavers and guides in show caves. Radon levels were measured using passive integrating monitors based on LR-115 detectors (for 2 months exposures) and Lucas cells (for grab sampling). Radon activity concentrations range between 10 and 2410 Bq m–3 for long-term measurements and 50 and 10150 Bq m–3 in grab sampling. The annual effective dose estimates range from 0.002 to 15.5 mSv. The results show that, in specific conditions, doses to cavers and guides may be higher than for miners in Polish underground hard-coal mines. However the highest value is lower than the recommended occupational limit for radiation exposure, i.e., 20 mSv.
Atmospheric radon concentrations were monitored from autumn 2004 to winter 2007 in an abandoned coal mining area of SW Poland that contained various bedrock uranium contents, ranging from 1 to 8 ppm. Gamma spectrometric measurements of eU, eTh and K content in the bedrock were combined with radon-monitoring results at 77 points, obtained via Kodak LR-115 detectors. The average atmospheric radon concentration was high (70 Bq m–3), reaching its maximum in the tailing area (131 Bq m–3). Strong spatial and seasonal variations in atmospheric radon concentrations were observed. Spatial variations were correlated with changing basement uranium content. Seasonal changes were positively correlated with temperature and negatively with humidity, resulting in maximum atmospheric radon activity in the summer. The strong influence of local basement uranium content indicates its importance in planning monitoring campaigns.
In this paper, we present the results of the first experience for spring water 222Rn concentration continuous monitoring in Jowshan hot spring, SE Iran, from December 2007 to July 2008. This hot spring is located on the active Gowk Fault. In addition to physic-chemical parameters of water and water chemistry, dissolved radon, and air and water temperatures, were measured at 10-minute time intervals. Measurements and analyses correlated with seismological data within a radius 250 km from the spring. Relatively good relationships between radon level variations and earthquake frequency, especially for events which monitoring site lie within the stress-strain field of earthquake, were observed. Results show that radon precursor time negatively correlate with the distance between the epicenters and monitoring station, but positively correlate with the magnitude of the earthquake events. Nevertheless, continuous monitoring to attain local pattern is necessary. Temperature, electrical conductivity and pH measurements do not show any correlation with seismic activity and radon variations in this time-window of monitoring. Monthly spring water samples analyzing for major components demonstrate no mixing ground-water has been taken place during the period of monitoring. While deep temperature estimation based on the [Na–K–Ca] geothermometery shown coinciding of temperature increasing with radon anomaly in one case. More data and shorter sampling time interval for spring water is required before we can conclude that the variation of estimated deep temperature is feasible to be as an earthquake precursor.
Radon has continuously been monitored at the Roman spring of Tiberias, Israel since 2000 in the frame of an earthquake research project. However, there was no apparent earthquake related radon anomaly in 5 years of monitoring. Physical mechanisms behind periodic as well as transient radon variations were investigated. The radon signal contained periodic daily and non-periodic multi-day variations as well as seasonal patterns with maxima during winter. Spectral analysis showed diurnal and semidiurnal periodic constituents while tidal effects were absent. In 2003 the long-term average radon concentration dropped by 35%. Coevally, the diurnal and semi-diurnal radon variability considerably decreased. In contrast, the intensity of large-scale signals, corresponding to multi-day radon variability, increased. At this stage the level of the Kinneret Lake is suspected to be the driving force for the radon drop. Until 2003 the lake level hovered around –214 m below sea-level. In spring 2003 the lake level had risen by 4 m. The distance between the monitoring station and the lake shore is about 50 m. The radon concentration inversely followed the lake level with a time delay of about 3 months. Radon measured at a natural hot spring should depend on the flow rate of the hot water rising on the border faults of the pull-apart basin. Increased flow means less time for radon to decay and thus a positive correlation between the flow rate and the radon concentration is expected. Flow velocity is controlled by (i) the pressure at depth, and (ii) the fracture width. Both are affected by the loading forces of the graben filling to which the water column of the lake contributes. Due to the lack of data about the mass flow rates from the spring, a direct link between the flow rate and the radon concentrations cannot be proven. In fact, the hot water discharge seemed to be very stable in time. So, either minor changes of the flow rate affect the radon concentration or another mechanism is needed to explain the observations, e.g., the pressure-dependent gas solubility or the pressure-dependent mixing of different groundwater components. Nevertheless, this does not explain the appearance of long-periodic, intra-seasonal radon signals (with periods in the order of 1 month) which were practically absent before 2003. Such long-periodic radon signals were not reported till today.
222Rn (radon) is the major radioactive gas in volcanic area. The study of radon concentration variations in volcanic areas has been considered as a useful tool to investigate the volcanic activity in one area. Tatun Volcano Group, where close to Taipei basin and exhibits active fumaroles and hot springs, was chosen for first time systematical study of radon gas in Hsiao-You-Keng hydrothermal area of northern Taiwan. In addition to soil CO2 flux and gas compositions, radon concentrations in soil were measured in situ by an analogous radon sensor. The sensor is developed to separate the electronics from the measurement chamber, which contains the detector and the preamplifier completely covered by epoxy, and can be used in the aggressive environment. Combined with gas composition and helium isotopic data, we can conclude that the radon gas is mainly carried by the volcanic gases. Therefore, it is considered as a good proxy for monitoring the magma activity in this area. A monitoring station was newly setup for such purpose and the preliminary monitoring data will be presented in this study.
The radon exhalation has been measured for samples of coal ashes by the can technique. In this technique, the ratio of the radon content in the air inside the can and the total radium content of the sample is often regarded to be the approximation of the emanation coefficient. In fact it is the exhalation coefficient, measure of the exhalation from the sample, and depends strongly on the sample size and geometry. Analysis of the relation between the defined exhalation coefficient and the sample thickness resulted in the exponential function. The exponential function for thickness approaching zero results in exhalation coefficient equal 13%, which can be treated as an approximation of emanation coefficient.
The activity concentrations of the natural radionuclides, namely 238Ra, 232Th and 40K, are measured for soil samples collected from some locations of the Malwa region of Punjab. An HPGe detector, based on high-resolution gamma spectrometry system is used for the measurement of activity concentrations. The activity concentrations of 226Ra, 232Th and 40K in the soil from the studied areas varies from 23.3 Bq kg–1 (Jagraon) to 43.6 Bq kg–1 (Ludhiana), 104 Bq kg–1 (Raikot) to 148 Bq kg–1 (Kauli) and 290 Bq kg–1 (Rajpura) to 394 Bq kg–1 (Sarhind) having an overall mean value of 32 Bq kg–1, 126 Bq kg–1 and 348 Bq kg–1 respectively. The radium equivalent activity (Raeq) in these soil samples ranges from 200 Bq kg–1 (Jagraon) to 264 Bq kg–1 (Kauli) having a mean value of 237 Bq kg–1. Corresponding indoor and outdoor annual effective doses range from 0.45 to 0.59 mSv and 0.11 to 0.15 mSv and average 0.53 and 0.13 mSv. The external hazard index (Hex) for soil samples of the study area are lower than unity; therefore, according to the Radiation Protection 112 (European Commission, 1999) report, soil from these regions is safe and can be used as a construction material without posing any significant radiological threat to population.
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.