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1.
Radon and its progeny have been recognized as one of the major contributors to the natural radiation and health hazards in the human dwellings. Even lung cancer is expected if it is present in enhanced levels beyond maximum permissible limit. This paper reports the measurements of indoor radon and its progeny in the urban dwellings of the Etah district of Uttar Pradesh province in Northern India using the cellulose nitrate (LR-115 type-II) plastic track detectors. It is found that the values of radon concentration vary from 3.52 to 248.64 Bq m−3 with a standard deviation of 69.19. The values of radon progeny concentration vary from 0.38 to 26.88 mWL with a standard deviation of 7.48. The effective dose has been calculated and found to vary from 0.05 to 3.76 mSv year−1 with a standard deviation of 1.05. The lifetime fatality risk is found to vary from 0.04 × 10−4 to 2.90 × 10−4. The results have been compared with the results reported in the rural areas of the same district.  相似文献   

2.
 The purpose of this study was to compare regional patterns of indoor radon concentration with uranium-bearing rock zones and county populations in Texas. Zones yielding radon concentrations that are relatively high for Texas include shale and sandstone in northwest Texas; red beds in north-central Texas; felsic volcanic rocks in west Texas; and sandstone, limestone, and igneous rocks in central Texas. Located in northwest Texas, only five of the 202 counties evaluated have mean indoor radon concentrations above 4.0 pCi l–1. Two of those counties have populations above the state median of 20 115. The highest county mean concentration is 8.8 pCi l–1. Results of this study suggest that (1) regional geology influences indoor radon concentrations in Texas, (2) statewide, the radon concentrations are relatively low, (3) highly populated counties do not coincide with regions of high indoor radon concentration, and (4) regions that may warrant further monitoring include northwest Texas and, to a lesser degree, west and central Texas. Received: 8 August 1995 · Accepted: 6 September 1995  相似文献   

3.
 Generalized geologic province information and data on house construction were used to predict indoor radon concentrations in New Hampshire (NH). A mixed-effects regression model was used to predict the geometric mean (GM) short-term radon concentrations in 259 NH towns. Bayesian methods were used to avoid over-fitting and to minimize the effects of small sample variation within towns. Data from a random survey of short-term radon measurements, individual residence building characteristics, along with geologic unit information, and average surface radium concentration by town, were variables used in the model. Predicted town GM short-term indoor radon concentrations for detached houses with usable basements range from 34 Bq/m3 (1 pCi/l) to 558 Bq/m3 (15 pCi/l), with uncertainties of about 30%. A geologic province consisting of glacial deposits and marine sediments was associated with significantly elevated radon levels, after adjustment for radium concentration and building type. Validation and interpretation of results are discussed. Received: 20 October 1997 · Accepted: 18 May 1998  相似文献   

4.
 Radon is a significant component of the groundwaters that discharge in the springs of Szczawno Zdrój and are recognized as medicinal. However, among the five exploited springs adjoining each other, it is only in Marta Spring that radon occurs in large concentrations (up to 325.6 Bq/dm3). Therefore, the authors have made an attempt to describe and clarify this fact. They found out from their own research and archival data that 222Rn dissolves in the waters of Marta Spring after acidulous waters of deep circulation have mixed with poorly mineralized shallow waters in their outflow zone. The genesis of the gas is determined by the content of its parent nuclide, 226Ra, in the sandstones in the vicinity of the intake. The volume of the rocks providing radon to the waters of this intake has been estimated at several hundred cubic metres. No seasonal fluctuations in radon concentration have been observed and 222Rn concentration changes do not seem to be influenced by changes in the concentration of other chemical components of the waters or by the discharge of the intake. The process of dissolving 222Rn in the medicinal groundwaters of Marta Spring is the last, the shortest, and the most local of the processes that form the chemical composition and the physical properties of these waters. Received: 7 January 2000 · Accepted: 12 August 2000  相似文献   

5.
 Radon concentration was measured in 133 water samples from tubewells, handpumps, dug wells and springs of the Doon Valley, Outer Himalaya, India. The observed radon values were found to vary from 10 to 154 Bq/l whereas radium in selected water samples varied from 0.11 to 0.75 Bq/l. Three different clusters of high radon values were observed in the north-western, central and south-eastern parts of the Doon Valley. These clusters were found to be associated with tectonics (thrust/fault) and associated uranium mineralization in the area. In general, radon concentration in groundwater was found to be positively correlated with the depth of the wells, whereas no significant correlation was observed between radon concentration in groundwater and the water temperature, pH value, conductivity and altitude of the water samples. An attempt has also been made to determine the nature and extent of aquifers in the Doon Valley on radon concentration in groundwater. The variation in radon concentration within the groundwater of the study area was found to be controlled by the neotectonic activity and geohydrological processes that occur in the area. The impact of these activities on radon concentration in groundwater are discussed. Received: 17 September 1999 · Accepted: 11 April 2000  相似文献   

6.
Radon measurements in soil and groundwater (springs, thermal springs and handpumps) were made in a variety of lithological units including major thrusts between Mandi and Manali in Himachal Himalaya. Analysis of radon data in light of lithological controls and influence of deep-seated thrusts has been made to elucidate the causative factors for anomalous emanation of radon. The lithological types include banded gneisses, schists, quartzite, granite, phyllites, volcanics and mylonites. The low-grade metasedimentries of Shali and Dharamsala generally show low and narrow range of radon concentration in water (5.6–13.4 Bq/l) as well as in soil (1.8–3.2 kBq/m3) except for the samples related to thrusts. On the other hand, sheared and deformed rocks of Chail and Jutogh show moderate radon content (average 5.03 kBq/m3, range 2.9–11.1 kBq/m3) in soil. However, the groundwater radon concentration shows wide variation in different types of sources (2.1–80.8 Bq/l). The quartzite and volcanic rocks of Rampur formation in this area present as a window separated by Chail thrust. Radon emanations on these rock types are relatively high (6.3–68.1 Bq/l in water and 5.5–15.9 kBq/m3 in soil) and are exceptionally high in samples that are related to uranium mineralization, deep-seated thrusts and hot springs (13.5–653.5 Bq/l). It is generally observed that anomalous high radon content is associated with mineralization, deeper source and tectonic discontinuities. Whereas it is obvious that subsurface radioactive mineralization would facilitate enhanced radon production, however, thrust plains provide easy pathways for escape of gases from the deeper sources. Shallow and deep sources of the groundwater have contrasting radon content particularly in the deformed and metamorphosed rocks of Jutogh and Chail. Shallow groundwater sources, mainly handpumps, have lower radon concentration due to limited superficial water circulation, whereas deeper sources, mainly perennial springs, show higher radon content because of larger opportunity for water–rock interaction.  相似文献   

7.
This paper presents the results of radon concentration measurements in the drinking water from the municipal water supply system and private wells of Xian, Xianyang and Baoji city of Shaanxi province of China. The measurements were carried out on 38 samples. Radon levels in drinking water in Xian, Xianyang and Baoji were found to be 5.78, 13.04 and 15.01 k Bq m–3, respectively. The AM radon concentration of private well water from Xianyang and Baoji is 28.84 k Bq m–3 and 38.85 k Bq m–3, respectively, which is 2.56 times and 3.14 times as high as that of tap water radon, respectively. The radiation risk of radon in water would be due to degassing and not due to drinking water. The domestic use of showers, humidifiers, and cooking, washing up, laundering, etc. may lead to an additional increase of the radon concentration in the indoor air. The observed radon concentration in drinking water from three main cities of Shaanxi Province can contribute to a 4.86 to 32.63% increase in indoor radon concentration and can cause 0.068±0.016 mSv y–1 to 0.177±0.045 mSv y–1 extra annual effective dose to males, 0.060±0.014 mSv y–1 to 0.155±0.039 mSv y–1 to females. The mean annual effective dose equivalents to males and females of Xianyang and Baoji from well water account for 25.94 to 39.75% of environmental radon and radon daughters annual effective dose equivalents. The radon concentrations in the well water from Xianyang and Baoji will bring a definite additional risk to the population.  相似文献   

8.
Two years of in situ radon concentration measurements in the atmospheric surface layer have been collected in a central Italy town (L’Aquila), located in the Aterno river valley. These data have been analyzed in order to study the controlling mechanisms of surface radon abundance; observations of coincident meteorological parameters confirmed the role of dynamics on the local removal rate of this tracer. The relatively high negative correlation of hourly data of surface wind speed and radon activity concentration (R = −0.54, on annual scale) suggests that dynamical removal of radon is one of the most important controlling processes of the tracer accumulation in the atmospheric surface layer. An attempt is made to quantify the precipitation impact on radon soil fluxes. No anticorrelation of radon and precipitation comes out from the data (R = −0.15), as in previous studies. However, since the main physical parameter affecting the ground radon release is expected to be the soil accumulation of water, snow or ice, the emission flux has also been correlated with soil moisture; in this way a much clearer anticorrelation is found (R = −0.54).  相似文献   

9.
A study of natural radionuclides and radon concentration of Hamirpur District of Himachal Pradesh, India is carried out using various methodologies. The activity concentration of the natural radionuclides viz. 226Ra, 232Th and 40K is measured using high-resolution-based HPGe detector. Indoor radon measurements in the dwellings of Hamirpur district is carried out using LR-115 type II cellulose nitrate films in the bare mode. The average activity concentrations of 226Ra, 232Th and 40K are 35.58, 54.95 and 580.58 Bq kg?1, respectively. The annual average indoor radon value in the study area varies from 173.90 to 198.25 Bq m?3, which is well within the recommended action level given by International Commission on Radiological Protection. The indoor radon values obtained in the present investigation are higher than the world average of 40 Bq m?3. Radon concentration in water samples is measured using RAD7, an active radon detector. The annual effective dose for stomach and lung is determined from the measured value of radon concentration in water. To assess the radiation hazard of the natural radioactivity in all samples to the people, the radium equivalent activity, external hazard index, lifetime fatality risk, absorbed dose rate and total annual effective dose is estimated. The results signify that the studied area does not possess any radiation hazards due to the presence of natural radioactivity concentration.  相似文献   

10.
Herein, the relationship between soil radon behavior and groundwater recharge in the town of Hosha, a semi-arid area of Jordan is explored. The annual rainfall average in this area is between 60–100 mm year−1. Soil radon concentration levels, using CR-39 detectors, have been measured at several depths. Nine sampling sites on a hill slope, in the summer and winter 2006 were chosen. Other soil parameters such as moisture, soil type and porosity were also measured. Correlation between the latter and the calculated effective diffusion coefficients, based on a linear approximation, was done in order to explore water movement. A weak correlation between the soil radon concentration and water recharge in this particular semi-arid area is observed. The results show that water recharge takes place vertically, i.e., water moves downward and in one of the nine sampling sites this movement seems to be more rapid compared to the other sites.  相似文献   

11.
Radon, thoron, and their progeny are largest contributors to the radiation dose received by human beings present in the natural environment. The indoor radon depends upon many factors such as building materials, meteorology, ventilation, and occupant’s behavior. This paper presents the measurements of indoor radon, thoron, and their progeny in four villages in rural area of district Kanshiram Nagar (Kasganj) in the state of Uttar Pradesh in Northern India. The concentration of indoor radon and thoron varies from 10.32 to 72.24 and 11.61 to 84.49 Bq m?3 with a geometric mean (GM) of 29.49 and 31.20 Bq m?3, respectively. The concentration of radon and thoron daughters was found to vary from 1.11 to 7.80 and 0.31 to 2.28 mWL, respectively. The annual exposure due to radon and thoron mainly vary from 0.05 to 0.30 WLM. The preliminary results (i.e., bare mode exposure of the LR-115 detectors fixed on cards) of this study have been separately published and compared this recent data with those results.  相似文献   

12.
The purpose of this study was to measure, compare, and analyze the air concentration of radon that was emitted to the atmosphere from construction materials such as cement brick, tile, red clay tile, and gypsum tile. The study method was to use continuous radon monitoring equipment (RTM 1688-2) to measure concentrations of radon and thoron contained in brick, tile, red clay tile, and gypsum tile. According to the measurement results, the cement brick among the four samples showed the highest measurement value for radon, while the red clay tile showed the highest measurement value for thoron. When the radon emission concentration was estimated based on materials required for construction per unit area (3.3 m2) in an actual construction, the cement brick had the highest measurement values for radon and thoron. This study confirmed the degree of radon emission from construction materials. The purpose of this study was also to suggest a method to examine the effects of radon and reduce the dose of personal radiation exposure. It is believed that the government should be active in publicizing and managing use of construction materials that have lower levels of radon emission.  相似文献   

13.
The dissolved fluoride (F−) in the Lower Ganges-Brahmaputra-Meghna (GBM) river system, Bengal basin, Bangladesh, was studied during 1991–1993 to determine its distribution and source in the basin, and its annual flux to the Bay of Bengal. The concentration of dissolved F− varied between 2 and 11 μmol l−1 with statistically significant variations both spatially and temporally in the basin. Such variations are attributable to the geology of the individual subbasins (Ganges, Brahmaputra and Meghna), dilution by rainwater during monsoon and groundwater contribution to the river systems during dry season. Correlation coefficients among F− and major cations and anions suggest diverse inorganic processes responsible for regulating the concentration of F− in these river systems. However, fluorite seems to be one of the major sources of dissolved F−. The concentration of F− in the Lower GBM river system is low compared to the rivers draining Deccan Plateau and arid regions of the subcontinent, for example, Yamuna and its tributaries. However, it is within the range of most of the other Peninsular and Himalayan rivers. The GBM system contributes about 115×103 tonnes year−1 of dissolved F− into the Bay of Bengal, and thus accounts for about 3% of the global F− flux to the oceans annually. Received: 19 May 1999 · Accepted: 11 October 1999  相似文献   

14.
The low-pressure stability of clinohumite has been investigated in phase-equilibrium experiments on the reaction forsterite + brucite = clinohumite. The reaction was bracketed between 2.45 and 2.84 GPa at 650 °C, extending to between 1.37 and 1.57 GPa at 850 °C. At temperatures above the reaction brucite = periclase + vapour, the reaction clinohumite = forsterite + vapour was bracketed between 1.27 and 1.52 GPa at 900 °C, rising to between 1.90 and 2.00 GPa at 1000 °C. The position of the reaction forsterite + brucite = clinohumite is ∼0.5 GPa below the position determined in previous work, the difference arising either from pressure uncertainties in both studies, from enhanced reaction to clinohumite in this study due to the presence of excess brucite in the starting material, or from different concentrations of defects in the two samples. The brackets on the reaction were combined with other measured and estimated thermodynamic data for clinohumite to determine its enthalpy of formation and entropy, in a revised version of the thermodynamic dataset of Holland and Powell (1998). The values obtained were ΔH f =−9607.29±3.05 kJ mol−1, S=445 J mol−1 K−1. These data were used to calculate positions of other reactions involving clinohumite. The calculations suggest a larger stability field for clinohumite than implied by the results of previous experimental studies, indicating a need for more high-pressure phase-equilibrium studies to provide better thermodynamic data. Received: 30 April 1999 / Accepted: 8 November 1999  相似文献   

15.
In the past several decades, the techniques used to discern the different sedimentary fractions of P have been refined. This has allowed for a better understanding of P burial of the different P fractions and diagenetic reactions and, ultimately, the constraining of P residence time in the oceans. P sequential extraction was performed on eight sediment cores (between 16 and 24 cm deep) collected along a salinity gradient from the Ojo de Liebre Lagoon and the salt evaporation saltern of Guerrero Negro, Baja California Sur, Mexico in order to determine, under purely diagenetic conditions (in the absence of anthropogenic activities and biogenic sediment reworking), the fractionation and flux of P to the sediments. The majority of P was found in the authigenic fraction (37 ± 5.4% to 53 ± 8.9%), with P associated to organic matter comprising the overall smallest percentage (0.25 ± 0.43% to 21 ± 6.0%) relative to total P. The average flux of total P to the sediments for all the sites was found to be (451 ± 127) × 10−4 mol m−2 year−1, up to several orders of magnitude greater than those found in other studies. It is concluded that P is most likely transformed from P associated to organic matter to the authigenic mineral phase and that P was retained in the sediments in its mineral form rather than in reactive forms. This particular study area has the ability to retain large quantities of P in the sediments.  相似文献   

16.
 Impact of catchment erosion and the resultant reservoir siltation from a tropical environment is reported here to discuss the effect of a reservoir in the natural degradation of an evergreen-forested segment. While an area of 8.01 km2 has been affected by direct inundation at the full reservoir level, another 2.6 km2 area once under thick forest cover, had also lost its identity over the last 38 years by indirect degradation. This zone mainly falls in the confluence of tributaries, namely Neyyar and Mullayar, with the reservoir. The capacity of the reservoir was found to be reduced by 28.8 Mm3 during this period and the annual average loss is calculated as 0.75 Mm3 (0.71%), indicating the intensity of erosion from the catchment zone. In case the proposed upper dam in the reservoir comes into existence, an additional area of 2.4 km2 from the virgin forest would be submerged and more area would face degradation around the inundated zone. Received: 29 July 1998 · Accepted: 16 November 1998  相似文献   

17.
 Infrared absorption spectra of brucite Mg (OH)2 were measured under high pressure and high temperature from 0.1 MPa 25 °C to 16 GPa 360 °C using infrared synchrotron radiation at BL43IR of Spring-8 and a high-temperature diamond-anvil cell. Brucite originally has an absorption peak at 3700 cm−1, which is due to the OH dipole at ambient pressure. Over 3 GPa, brucite shows a pressure-induced absorption peak at 3650 cm−1. The pressure-induced peak can be assigned to a new OH dipole under pressure. The new peak indicates that brucite has a new proton site under pressure and undergoes a high-pressure phase transition. From observations of the pressure-induced peak under various P–T condition, a stable region of the high-pressure phase was determined. The original peak shifts to lower wavenumber at −0.25 cm−1 GPa−1, while the pressure-induced peak shifts at −5.1 cm−1 GPa−1. These negative dependences of original and pressure-induced peak shifts against pressure result from enhanced hydrogen bond by shortened O–H···O distance, and the two dependences must result from the differences of hydrogen bond types of the original and pressure-induced peaks, most likely from trifurcated and bent types, respectively. Under high pressure and high temperature, the pressure-induced peak disappears, but a broad absorption band between 3300 and 3500 cm−1 was observed. The broad absorption band may suggest free proton, and the possibility of proton conduction in brucite under high pressure and temperature. Received: 16 July 2001 / Accepted: 25 December 2001  相似文献   

18.
 Nakka vagu, a tributary of the River Manjira in the Medak district of Andhra Pradesh, has a catchment area of ∼500 km2. Patancheru is an industrial development area (IDA) near the vagu. There are about 350 industries of varied nature (pulp, plastic, bulk drugs, pharmaceuticals, paints and steel rolling mills) that are engaged in the manufacture/processing of their respective products and that use water extensively. The hydrogeological setup has a bearing on the widespread contamination in the area because of discharge of industrial effluents into open land and streams. Several dug wells and boreholes situated in the study area have been monitored for water level fluctuations and quality variations. Pumping tests have been conducted to evaluate aquifer parameters. The geology, drainage, chemistry and other related anthropogenic factors play a major role in the spread of pollution in the area. Hence, it is very important to determine the degree of vulnerability to pollution based on hydrogeological factors. Amidst the granite terrain, the Nakka vagu has been identified as a paleo-channel (composed of clay–silt–sand facies); its presence in the area has immensely increased the spread of groundwater contamination. The transmissivity of the alluvial aquifer varies from 750 to 1315 m2/day. The adjoining granite has a transmissivity that varies from 30–430 m2/day. The thickness of the valley fill in the discharge region is about 10–12 m, with a lateral spread of 500–700 m, east of Nakka vagu. Received: 17 November 1999 · Accepted: 14 March 2000  相似文献   

19.
This paper presents a study on Manasbal lake, which is one of the high altitude lakes in the Kashmir Valley, India. Eighteen water samples were analysed for major ions and trace elements to assess the variability of water quality of the lake for various purposes. Geostatistics, the theory of regionalized variables, was then used to enhance the dataset and estimate some missing spatial values. Results indicated that the concentration of major ions in the water samples in winter was higher than in summer. The scatter diagrams suggested the dominance of alkaline earths over the alkali elements. Three types of water were identified in the lake that are referred to as Ca–HCO3, Mg–HCO3 and hybrid types. The lake water was found to be controlled by rock–water interaction with carbonate lithology as a dominant source of the solutes. The major (Ca2 + , Mg2 + , Na + , K + , NO3 and HCO3-{\rm{HCO}}_{3}^{-}, CO3 and Cl) and trace elements of the lake water were within the World Health Organization standards, therefore the lake water was considered chemically safe for drinking purposes. Although NO3 concentration (ranging from 1.72 to 2 mg/L), is within the permissible limit and not very alarming, the gradually increasing trend is not acceptable. It is however, important to guard its spatio-temporal variability as the water is used for domestic as well as agricultural purposes. This study is significant as hydrogeological information on such high altitude lakes in India is scanty.  相似文献   

20.
Summary The temperature dependence of photoluminescence emission of a natural fluorite has been studied in the wavelength region of 380–500 nm and in the temperature range of 17.5–300 K. The emission spectra of the sample show a broad emission band between 380 and 500 nm for temperatures above 100 K. At 100 K and below, vibronic lines appear on the emission band at approximately 413.3, 418.1, 419.3, 420.2, 423.9 and 427.1 nm. This broad emission band and the vibronic lines in fluorite are usually associated with phonon-coupled electronic transitions from 4f65d to 4f7 in the Eu2+ ion. Temperature dependences of the peak energy, intensity and full-width at half-maximum of the broad emission band are discussed, and the behaviour explained in terms of a configurational coordinate model. The excited state vibrational energy was obtained to be 0.023 ± 0.001 eV and this is lower than the LO phonon energy of 0.062 eV in pure fluorite. The activation energy of thermal quenching of the photoluminescence intensity was found to be 0.022 ± 0.002 eV.  相似文献   

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