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1.
本文介绍了地震氡观测仪计量检定系统（氡室）的建设背景及结构组成。氡室具有氡体积活度（氡浓度）实时监测、动态补氡、氡期望值可调、稳定性好等特点。在氡室调试实验中进行了氡室的漏气率实验及4次补氡实验,计算出氡室的氡漏气率为0.0001393Bq/min,氡发生率为23.35Bq/min。根据《测氡仪检定规程》（JJG 825—2013）的技术要求进行计量效能验证,表明氡室的氡体积活度（氡浓度）为800Bq/m3、1500Bq/m3、3000Bq/m3、6000Bq/m3和15000Bq/m3时,连续8h稳定性均优于5%;为6000Bq/m3时,72h稳定性优于5%,符合国家计量技术规范对氡室计量标准的要求。  相似文献   

2.
Radon in the Earth’s crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. 222Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then 222Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq·m?3 with geometrical mean value of 302 ± 84 Bq·m?3. Th significance of this work is its usefulness from radiation protection point of view.  相似文献   

3.
In the past decade many international studies have established that the radioactive gas radon is responsible to a large extent for the radiation dose absorbed by the population. Consequently the Swiss Federal Health Office started and sponsored a research program called RAPROS (Radon Programm Schweiz, 1987–1991) to assess the relevant aspects of radon exposure in Switzerland.The average indoor radon concentration in Swiss living rooms is about 60–70 Bq m−3, this corresponds to an annual dose of about 2.2 mSv, but values largely exceeding 1000 Bq m−3 were also found. Often very strong temporal fluctuations of indoor radon concentrations were measured.The ground directly underneath buildings is the main radon source of indoor radon. The material properties that influence the radon production and transport in soils are: radium content, emanating coefficient and soil gas permeability; among them only the last one can vary over many orders of magnitude. The permeability is consequently the decisive factor that enables radon transport in the subsurface. To characterize the radon potential of soils a radon availability index (rav) was introduced.Our investigations have also shown that in karst systems the radon concentration in the air is often increased to 10–100 times higher than in buildings. This radon-charged air is able to travel over considerable distances through faults and cavities in the underground and reach living rooms built over karstified areas.  相似文献   

4.
The field radiometric and laboratory measurements were performed at the Sin Quyen copper deposit in North Vietnam. The field gamma-ray spectrometry indicated the concentration of uranium ranging from 5.5 to 87 ppm, thorium from 5.6 to 33.2 ppm, and potassium from 0.3 to 4.7%. The measured dose rates ranged from 115 to 582 nGy/h, the highest doses being at the copper ore. Concentrations in the solid samples were in the range of 20–1700 Bq/kg for uranium, 20–92.7 Bq/kg for thorium, and 7–1345 Bq/kg for potassium. The calculated doses were from 22 to 896 nGy/h; both measured and calculated dose rates are mostly related to uranium. Concentrations of radium in water samples were below 0.17 Bq/L. Uranium in water samples was significantly higher than the hydrogeological background; the maximum of 13 Bq/L was at the waste zone pool, but neither radium nor uranium were present in tap water. Radon concentration in the dwelling air was from 42 to 278 Bq/m3 for 222Rn and from 8 to 193 Bq/m3 for 220Rn. The estimated committed dose rates were principally related to 222Rn concentration and ranged from 1.1 to 8.1 mSv/y.  相似文献   

5.
B?i?a-?tei mine is an open pit mine in NW Romania (West Carpathian Mountains). It was the largest surface uranium deposit in the world. Two means of uranium transport and dissemination were used over time. The first was the natural way, represented by transportation of geological sediments by Cri?ul-B?i?a River that crosses the B?i?a surface deposit. These sediments were used as building materials (stone, gravel, sand). The second way was related to the people living in this valley, who used also the uranium waste as building material. The preliminary indoor radon concentrations measured in the buildings ranged from 40 to 4000 Bq m?3 with a mean value of 241 Bq m?3. A focused radon survey facilitated the selection of 20 houses with the highest indoor radon that were therefore proposed for remediation. To find the radon sources of these houses, systematic investigations on radon were performed. The remedial measures for these 20 houses were tested on a chosen pilot house.  相似文献   

6.
Summary Radon (Rn222) profiles were made over southwest Arizona from 300 m to 4km altitude. A temperature inversion near 2000 m and a stable radon concentration averaging 32.0 pc m–3 at 2000 m were characteristic of morning flights. At 300 m there was a definite pattern of high radon concentrations in the early morning and lower concentrations by noon. At 760 m the radon concentration increased between the times of ascent and descent. This pattern resulted from the trapping of radon close to the ground during stable night-time conditions and its subsequent upward dispersal with solar heating. The day-to-day variation in radon concentrations at higher levels cannot be attributed to local upward transport by diffusion but must have resulted from larger scale circulations. Above 2000 m there are no conclusive differences between morning, afternoon and evening profiles. Low concentrations of radon were measured during one late evening profile when there was definite subsidence and advection of drier air into the region.  相似文献   

7.
Discharge in mountain streams may be a mixture of snowmelt, water from surface runoff, and deep return flow through valley bottom alluvia. We used δ18O and δ2H, solute concentrations, and 222Rn to determine water sources of a headwater stream located at the McDonald Creek watershed, Glacier National Park, USA, during summer recession flow period. We analysed minimal water isotope ranges of ?17.6‰ to ?16.5‰ and ?133‰ to ?121‰ for δ18O and δ2H, respectively, potentially due to dominance of snow‐derived water in the stream. Likewise, solute concentrations measured in the stream through the watershed showed minimal variation with little indication of subsurface water input into the stream. However, we observed 222Rn activities in the stream that ranged from 39 to 2646 Bq/m3 with the highest value measured in middle of the watershed associated with channel constriction corresponding to changes in local orientation of underlying rocks. Downstream from this point, 222Rn activity decreased from 581 to 117 Bq/m3 in a series of punctuated steps associated with small rapids and waterfalls that we hypothesized to cause radon degassing with a maximum predicted loss of 427 Bq/m3 along a 400 m distance. Based on mass balance calculations using 222Rn activity values, streamflow, and channel characteristics, we estimated that groundwater contributed between 0.3% and 29% of total flow. Overall, we estimated a 5.9% of groundwater contribution integrated for stream reach measured at McDonald Creek during recession flow period. Finally, a lower mean hyporheic flux of 14 m3/day was estimated compared to the groundwater flux of 70 710 m3/day. These assessments highlight the potential for radon as a conservative tracer that can be used to estimate subsurface water contribution in mountain streams within a complex geologic setting. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

8.
In the present study, experiments have been carried out to calibrate LR-115 alpha detector films in bare and cup-mode exposure for the measurement of radon and thoron concentrations in soil gas. Results showed non-uniformity in track formation on the films in bare-mode exposure. However, in cup-mode exposure the non-uniformity was reduced to a greater extent. The calibration factors obtained for radon in bare- and cup-mode exposures are 0.049 and 0.034 tr. cm?2 per Bq m?3 d, respectively. An attempt has been made to calibrate the radon-thoron discriminative cup with LR-115 films for simultaneous measurements of radon and thoron. This paper also presents the preliminary results of radonthoron monitoring in Tatun volcanic areas of northern Taiwan for the first time using radon-thoron discriminators with LR-115 films. The results show that the safe temperature to install the LR-115 films in volcanic areas is ≤ 65°C and thoron concentration in the study area is low.  相似文献   

9.
This paper considers the geoecological impacts of eruptions on Karymskii Volcano and the Tokareva crater for the 1996–2008 period, which resulted in changes in (a) the relief around these edifices, (b) the discharge and composition of water in the Karymskii River and other streams in the area, and (c) the discharge and composition of gases in thermal springs. It was found that the concentration of CH4 previously had been abnormally high in free gases that emanate from the new Piipovskii Springs and an explanation is provided of the decrease in their concentration over time. We detected variations in the radon activity, OARn (Bq/m3), in free gases that are released in the Karymskii caldera hydrothermal occurrences; the variations are consistent with those in the eruptive activity of Karymskii Volcano in 2005–2006. We describe permafrost rocks in the Karymskii caldera that favor the generation of a cryolithic zone.  相似文献   

10.
Radon and its short-lived progeny are exposed to most human exposures as a natural source of radiation. Many studies have presumed that one of the most common incidences of lung cancer, colon cancer, and stomach cancer is caused by radon-contaminated water. In this study, water was collected from different groundwater sources in the Hafr Al Batin area, Saudi Arabia, and the radon concentration was investigated using an electronic portable radon detector. The annual effective dose of radon exposure by ingestion and inhalation of water is calculated from that radon concentration for the different age groups to assess the risk of radon exposure. The calculated annual effective doses are then compared with the international standard of risk limit as directed by the international organizations. The estimated radon concentration for groundwater samples is found to be between 0.03 and 3.20 Bq/L with an average value of 1.16 Bq/L. These estimated values are below the safety limits set by the USEPA and EAEC and far below those recommended by the UNSCEAR, EC, and WHO standards. The calculated annual effective dose of radon exposure for the different age groups ranging from infant to adult is found to be in the range of 0.05 to 16.24 μSv/year, with a mean value of 5.89 μSv/year, which is in the safe limit recommended by the EC and WHO. The obtained results of this present study will support the authority and regulators who are responsible for controlling and strategizing to ensure public safety against radon exposure.  相似文献   

11.
Radium-226 (226Ra) activities were measured in the surface water samples collected from the Arctic Ocean and the Bering Sea during the First Chinese National Arctic Research Expedition. The results showed that 226Ra concentrations in the surface water ranged from 0.28 to 1.56 Bq/m3 with an average of 0.76 Bq/m3 in the Arctic Ocean, and from 0.25 to 1.26 Bq/m3 with an average of 0.71 Bq/m3 in the Bering Sea. The values were obviously lower than those from open oceans in middle and low latitudes, indicating that the study area may be partly influenced by sea ice meltwater. In the Bering Sea, 226Ra in the surface water decreased northward, probably as a result of the exchange between the 226Ra-deficient sea ice meltwater and the 226Ra-rich Pacific water. In the Arctic Ocean, 226Ra in the surface water increased northward and eastward. This spatial distribution of 226Ra reflected the variation of the 226Ra-enriched river component in the water mass of the Arctic Ocean. The vertical profiles of 226Ra in the Canadian Basin showed a concentration maximum at 200 m, which could be attributed to the inputs of the Pacific water or/and the bottom shelf water with high 226Ra concentration. This conclusion was consistent with the results from 2H, 18O tracers.  相似文献   

12.
Groundwater-surface water interactions (GSI) connect rivers and streams with riparian areas and the adjacent aquifer. Although these interactions exert a substantial control of quantity and quality of both groundwater and surface water, knowledge on GSI along rivers at the regional scale, particularly for inland waterways, is still limited. We investigated GSI along the river Moselle, an important federal inland waterway in Germany, by using radon and tritium to identify gaining (water flux from the aquifer to the surface water) and losing (water flux from the surface water to the aquifer) stream conditions, respectively. Gaining stream conditions were identified by continuously measuring radon along the river during boat surveys with a high spatial resolution (every 2 km) during intermediate (October 2020) and near low flow conditions (August/September 2021). The tritium concentrations in surface water and groundwater and the resulting tritium inventories were used to characterize losing stream conditions Monthly tritium inventories from 2017 to 2022 revealed a mean loss for the whole period of 20.3 % and a mean gain of 21.8%. Both were probably triggered by a combination of losing stream conditions and flood-induced mass transfer of water from the aquifer back into the river as well as discharge fluctuations. At the investigated site Lehmen there were direct indications of an influence of surface water due to elevated tritium concentrations in the groundwater (up to 13.3 Bq L−1). Using radon mass balance modelling, good agreements of simulated versus measured radon data with respect to two groundwater end-member scenarios were obtained during intermediate flow (Spearman's ρ: 0.97 and 0.99; MAE: 10.1 and 3.4 Bq L−1) and near low flow (Spearman's ρ: 0.97 and 0.99; MAE: 11 and 6.5 Bq L−1). Considerable groundwater inflow was limited to the meander of Detzem, where cumulated groundwater inflow of about 19 m3 s−1 (9.5% of total discharge) and 4.2 m3 s−1 (3.8% of total discharge) was simulated during intermediate and near low flow, respectively. However, the groundwater inflow was relatively low compared to alpine streams, for example. The study will help to better identify and quantify GSI at the regional scale and provide methodological guidance for future studies focusing on inland waterways.  相似文献   

13.
Short‐lived fallout isotopes, such as beryllium‐7 (7Be), are increasingly used as erosion and sediment tracers in watersheds. 7Be is produced in the atmosphere and delivered to the Earth's surface primarily in precipitation. However, relatively little has been published about the variation in 7Be wet deposition caused by storm type and vegetation cover. Our analysis of precipitation, throughfall, and sediments in two forested, headwater catchments in the mid‐Atlantic USA indicates significant variation in isotope deposition with storm type and storm height. Individual summer convective thunderstorms were associated with 7Be activity concentrations up to 5.0 Bq l?1 in precipitation and 4.7 Bq l?1 in throughfall, while single‐event wet depositional fluxes reached 168 Bq m?2 in precipitation and 103 Bq m?2 in throughfall. Storms originating from the continental USA were associated with lower 7Be activity concentrations and single‐event wet depositional fluxes for precipitation (0.7–1.2 Bq l?1 and 15.8–65.0 Bq m?2) and throughfall (0.1–0.3 Bq l?1 and 13.5–98.9 Bq m?2). Tropical systems had relatively low activity concentrations, 0.2–0.5 Bq l?1 in precipitation and 0.2–1.0 Bq l?1 in throughfall, but relatively high single‐event depositional fluxes due to large rainfall volumes, 32.8–67.6 Bq m?2 in precipitation and 25.7–134 Bq m?2 in throughfall. The largest sources of 7Be depositional variation were attributed to storm characteristics including precipitation amount and maximum storm height. 7Be activity associated with fluvial suspended sediments also exhibited the highest concentration and variability in summer (175–1450 Bq kg?1). We conclude the dominant source of variation on event‐level 7Be deposition is storm type. Our results illustrate the complex relationships between 7Be deposition in precipitation and throughfall and demonstrate event‐scale relationships between the 7Be in precipitation and on suspended sediment. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

14.
Radon (222Rn) concentration in geothermal waters and CO2-rich cold springwaters collected weekly in duplicate samples from four stations in northern Taiwan were measured from July 1980 to December 1983. Seven spike-like radon anomalies (increases of 2 to 3 times the standard deviation above the mean) were observed at three stations. Following every anomaly except one, an earthquake ofM L above 4.6 occurred within 4 to 51 days, at an epicentral distance 14 to 45 km, and at a focal depth of less than 10 km. The distribution of the earthquakes preceded by radon anomalies is skewed in certain directions from the radon stations; the radon stations seem to be insensitive to earthquakes occurring in the other directions. At the fourth station, near a volcanic area, much gas (mainly CO2) is discharged from the well, together with hot water. A very high concentration of radon was detected in the discharged gas; therefore trapping of gas in the water can result in anomalously high radon contents. According to limited measurements, the radon concentration in water appears to be undersaturated with respect to that in gas. This suggests that hot water is very susceptible to radon loss, and monitoring of radon in gas is more desirable.  相似文献   

15.
Monitoring of Xe and Kr radionuclides was conducted from August 2006 to 30 July 2008 within the framework of ISTC Project #2133. Cherepovets City in Vologda Province and St. Petersburg were chosen as monitoring locations. Kr–Xe concentrate samples were obtained as a result of processing of several thousand m3 of atmospheric air. New results of 85Kr monitoring show, that for last 15 years, the 85Kr volumetric activity in the atmospheric air of the northwest region of Russia has increased approximately 50% and has achieved a level of 1.5 Bq/m3. This value correlates well with similar data for Western Europe and Japan. The xenon fraction (80–160 cm3 under STP) is adsorbed on charcoal in the ampoule, which is measured in the well of HPGe gamma detector. Minimum detectable concentration (MDC) of 133Xe for this technique is 0.008 mBq/m3, and it is the most sensitive method used today. The 133Xe concentration in the atmospheric air of Cherepovets City varied in the monitoring period ranging from 0.09 to 2.5 mBq/m3. During the period of March 2007–30 July 2008, 133Xe activity concentration in the atmospheric air of St. Petersburg changed from background values (0.2–0.3 mBq/m3) to 185 mBq/m3 and for approximately 20% of the samples 135Xe was also measured with the 135Xe/133Xe activity ratio varied within the range of 0.03–3.5.  相似文献   

16.
There is very thin soil layer in karst rocky desertification areas in Southwest China,sediment deposition and sediment yield in the karst area affects the development of vegetation greatly.In the present study,the 137Cs technique was used to assess the rate of sediment deposition and sediment yield in a small karst catchment.The 137Cs inventory within the depression varied between 800 m-2 and 2,200 Bq m-2,with the mean value of 1,500.1 Bq m-2.The 137Cs reference inventory at a nearby reference site was 805.9 Bq m-2.It could be inferred to that sediment deposition had occurred in the catchment.The mean depth of sediments deposition in the depression was 6 cm and the deposition rate was approximately 0.13 cm yr-1.The analysis of the topographic characteristics of the catchment revealed that the sediment deposition occurred mainly at the lower part of the small catchment.Although,there was a sinkhole in the depression,little sediment had drained out with runoff through the sinkhole,because the local people built ridges around the sinkholes for storing water.According to this,sediment yield rate in the small catchment was estimated to be approximately 19.25 to 27.5 t km-2 yr-1,and the extremely low sediment yield was maybe the main obstacle to vegetation restoration in karst rocky desertification areas.  相似文献   

17.
This study shows the assessment of radiation hazard parameters due to terrestrial radionuclides in the soil around artisanal gold mining for addressing the issue of natural radioactivity in mining areas. Hence, the levels 238U, 232Th, 40K and 226Ra in soil (using gamma spectrometry), 222Rn in soil and 222Rn in air were determined. Radiation hazard parameters were then computed. These include absorbed dose D, annual effective dose E, radium equivalent activity Raeq, external hazard Hex, annual gonadal dose equivalent hazard index AGDE and excess lifetime cancer risk ELCR due to the inhalation of radon (222Rn) and consumption of radium (226Ra) in vegetation. Uranium (238U), thorium (232Th) and potassium (40K) averages were, respectively, 26, 36 and 685 Becquerel per kilogram (Bq kg?1). Soil radon (4671 Bq m?3) and radon in air (14.77 Bq m?3) were found to be less than worldwide data. Nevertheless, the average 40K concentration was 685 Bq kg?1. This is slightly higher than the United Nations Scientific Committee on the Effects of Atomic Radiation average value of 412 Bq kg?1. The obtained result indicates that some of the radiation hazard parameters seem unsavory. The mean value of absorbed dose rate (62.49 nGy h?1) was slightly higher than average value of 57 nGy h?1 (~?45% from 40K), and that of AGDE (444 μSv year?1) was higher than worldwide average reported value (300 μSv year?1). This study highlights the necessity to launch extensive nationwide radiation protection program in the mining areas for regulatory control.  相似文献   

18.
As one component of ChinaFLUX, the measurement of CO2 flux using eddy covariance over subtropical planted coniferous ecosystem in Qianyanzhou was conducted for a long term. This paper discusses the seasonal dynamics of net ecosystem exchange (NEE), ecosystem respiration (RE) and gross ecosystem exchange (GEE) between the coniferous ecosystem and atmosphere along 2003 and 2004. The variations of NEE, RE and GEE show obvious seasonal variabilities and correlate to each other, i.e. lower in winter and drought season, but higher in summer; light, temperature and soil water content are the main factors determining NEE; air temperature and water vapor pressure deficit (VPD) influence NEE with stronger influence from VPD. Under the proper light condition, drought stress could decrease the temperature range for carbon capture in planted coniferous, air temperature and precipitation controlled RE; The NEE, RE, and GEE for planted coniferous in Qianyanzhou are ?387.2 g C·m?2 a?1, 1223.3 g C·m?2 a?1, ?1610.4 g C·m?2 a?1 in 2003 and ?423.8 g C·m?2 a?1, 1442.0 g C·m?2 a?1, ?1865.8 g C·m?2 a?1 in 2004, respectively, which suggest the intensive ability of plantation coniferous forest on carbon absorbing in Qianyanzhou.  相似文献   

19.
— Indoor radon radioactivity in the rooms on the ground floor and first floor of the Physics Department, Faculty of Science, Universiti Brunei Darussalam was measured using a system that consists of an air filter pump, ZnS detector, photomultiplier tube and counter. Ground floor rooms' radon radioactivity was found to be about three times higher than that of the first floor. The maximum ground floor indoor radioactivity is only 0.39 Bqm?3, a value relatively low and safe compared to the mean outdoor radon concentration of 1.41 Bqm?3 measured (HU and TAN, 2000). The main source of radon emanation originates from the ground soil rather than the building materials.  相似文献   

20.
The article presents the results of studying radiocesium concentration and distribution between dissolved and particulate forms in ponds in the near zone of Fukushima Dai-ichi NPP NPP after the 2011 accident. The total concentration of 137Cs in pond water and its variations are shown to be largely governed by the concentration of particulate matter being as high as 68 Bq/L, compared with 5 Bq/L in solution. The values of the distribution coefficient Kd in the ponds are similar to those in rivers and in large flow-through lakes in the accidentally polluted zone at Fukushima Dai-ichi NPP. The contributions of the main competing ions K+ and NH 4 + to radiocesium desorption from solid particles into solution were similar for the ponds; however, their relative effect on dissolved radiocesium concentration varied over time because of variations in ammonium concentration.  相似文献   

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