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1.
AbstractThe ingestion of 226Ra, inhalation, and ingestion of 222Rn in water is considered the primary health risk for lungs and stomach. This study presents the concentrations of 226Ra and 222Rn in well and tap water collected from Sik, Malaysia, using HPGe and RAD7 detectors. Maximum average concentrations of 226Ra and 222Rn were found 47.6?±?3.6 mBq/l and 9.3?±?1.4?Bq/l in well water, respectively, and minimum were found 17.1?±?3.6 mBq/l and 1.6?±?1.0?Bq/l in tap water, respectively. A positive correlation (R=.88) was found between 226Ra and 222Rn determined by HPGe and RAD7 detectors, respectively. Infants in the age group of 0–1 y appeared to be at risk with respect to the annual effective doses from 226Ra and 222Rn as compared to the other age groups. However, annual effective doses for all three age groups from intake of 226Ra and 222Rn in well and tap drinking water were found below the World Health Organization (WHO) recommended level of .1 mSv/y. 相似文献
2.
A survey on radon (222Rn), thoron (220Rn) and its decay products (220RnD) was conducted in Chinese traditional residential dwellings constructed with loam bricks or soil wall. The activity concentrations
in 164 dwellings under investigation were 72.4±59.2 (arithmetic mean, AM) and 57.5±2.0 Bq m−3 (geometric mean, GM) for 222Rn, and 318±368 and 162±3.7 Bq m−3 for 220Rn, respectively. For 220RnD, 67 dwellings were studied. The AM of the 220RnD equilibrium equivalent concentration was 3.8±3.3 Bq m−3 with a maximum value of 15.8 Bq m−3. On the basis of these results, the average annual effective doses to the local residents due to radon and thoron exposure
were 1.44–4.62 mSv. Thoron contributes 12.9–56.6% to the total doses. Preliminary results show that there is a relation between
220RnD in air and 232Th in soil. The correlation factors of outdoor and indoor were 0.88 and 0.40. The 232Th activity content of Chinese soil is estimated to be about two times the world average. The traditional residential dwellings
with soil construction are still common in China. Further investigations on the 220Rn level in these dwelling with the aim of dose reduction are proposed. 相似文献
3.
Ingesting waters holding high levels of natural occurring radioactive element like Radon would contribute to increase in the effective dose received by people followed by an increased prevalence of cancer. The current study is an attempt to describe the extent of contribution of 222Rn to natural background radiation and the resultant effective dose to public of different age groups. In order to do so, 65 groundwater samples from selected parts of Bangalore city were collected and analyzed for radon activity using RAD7 radon monitor coupled with RAD H2O accessories. The radon activity was in the range of 3.05–696 Bq/L (mean: 91.39 Bq/L) and 92.31% of the groundwater samples recorded elevated radon concentration above the United States environmental protection agency (USEPA's) Maximum Contaminant Level (MCL) value of 300 pCi/L, corresponding to 11.1 Bq/L. The mean annual effective dose contribution of people falling under different age groups (viz., infants, children, teens: males and females, adults: males and females, pregnant and lactating women) due to ingestion of water-borne 222Rn ranged from 0.082 to 0.444 mSv/y and was found to be higher in all the age groups of males compared to respective female age groups, but well within the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) and World Health Organization (WHO) proposed limit of 1 mSv/y. 相似文献
4.
Aslı Kurnaz Muazzez Gezelge Aybaba Hançerlioğulları M. Atıf Çetiner Şeref Turhan 《人类与生态风险评估》2016,22(6):1375-1385
The activity concentrations of radionuclides in grape molasses soil samples collected from Zile (Tokat) plain in the Central Black Sea region of Turkey were measured by using gamma spectrometer with a NaI(Tl) detector. Also, the concentrations of 222Rn in soil samples and air were estimated essentially taking the activity concentrations of 226Ra measured in soil samples. Grape molasses soil samples with calcium carbonate content are used for sedimentation for making molasses in this region. The average activity concentrations of 232Th, 226Ra, 40K, and 137Cs were found as 62 ± 2, 68 ± 3, 479 ± 35, and 8.0 ± 0.3 Bq kg?1, respectively. The average concentrations of 222Rn in soil samples and air were estimated to be 50 kBq m?3 and 144 Bq m?3. From the activity concentrations, absorbed gamma dose rate in outdoor air (D), annual effective dose from external exposure (EE), annual effective dose from inhalation of radon (EI), and excess lifetime cancer risk (ELCR) were estimated in order to assess radiological risks. The average values of D, EE, EI, and ELCR were found to be 90 nGy h?1, 110 μSv y?1, 1360 μSv y?1, and 4 × 10?4, respectively. 相似文献
5.
Summary Measurements of the concentrations of222Rn, its short-lived decay products and of212Pb -212Bi were performed in 150 dwellings and in the open air in the Federal Republic of Germany. The concentration of222Rn was measured by electrostatic deposition of218Po. The concentrations of the short-lived decay products were measured by air sampling and alpha-spectroscopy. It was found that inside dwellings the average potential alpha-energy concentration of the short-lived daughters is about three times higher than in the open air. The total potential alpha-energy concentration indoors amounts to 2.6 · 10–3 Working Level (W. L.). Direct measurements of the equilibrium factor inside dwellings gave a mean value of 0.3. A strong dependence of the potential alpha energy concentration on the ventilation rate in dwellings has been observed. These ventilation effects exceed the effects caused by differences in the activity concentrations due to different building materials.The dose calculation results in an average dose to the whole lung due to the inhalation of short-lived radon daughters of about 0.05–0.2 mGy/a. An estimate of risk - based on the risk factors for uranium miners - shows an average lifetime risk of about 6 · 10–4 for the incidence of lung cancer caused by inhalation of radon and thoron daughters in dwellings in the Federal Republic of Germany.The research programme was supported by the Bundesminister des Innern of the Federal Republic of Germany 相似文献
6.
In this article, the levels of 222Rn concentrations, annual effective doses, and excess lifetime cancer risk estimations were investigated for water samples in the city of Osmaniye, located in the southern part of Turkey. The measurements were conducted using a radon gas analyzer (AlphaGUARD PQ 2000 PRO). The arithmetic average of 222Rn concentrations was 0.44 Bq.L?1 with a geometric standard deviation of 0.19 and geometric average 0.41 Bq.L?1. The results obtained were compared with the findings of other studies. All measured radon concentrations were below the values recommended by the World Health Organization and the U.S. Environmental Protection Agency. The associated radiological parameters such as annual effective doses (AED) and excess lifetime cancer risk (ELCR) from consumption of these waters were calculated. The computed average annual effective doses for ingestion and inhalation as well as excess lifetime cancer risk were estimated to be 1.13 μSv.y?1, 1.10 μSv.y?1, and 3.95 × 10?6, respectively. 222Rn concentration, AED, and ELCR interpolated values of the region were determined and mapped using the Kriging method. The results of radon concentrations in this study provide a data baseline for future studies on subsequent evaluations of possible future environmental contamination of Osmaniye Province. 相似文献
7.
Christopher S. Martens Thomas J. Shay† Howard P. Mendlovitz Daniel M. Matross‡ Scott R. Saleska‡ Steven C. Wofsy‡ W. Stephen Woodward Mary C. Menton §¶ José M. S. De Moura¶ Patrick M. Crill Osvaldo L. L. De Moraes†† Risonaldo L. Lima¶ 《Global Change Biology》2004,10(5):618-629
Radon‐222 (Rn‐222) is used as a transport tracer of forest canopy–atmosphere CO2 exchange in an old‐growth, tropical rain forest site near km 67 of the Tapajós National Forest, Pará, Brazil. Initial results, from month‐long periods at the end of the wet season (June–July) and the end of the dry season (November–December) in 2001, demonstrate the potential of new Rn measurement instruments and methods to quantify mass transport processes between forest canopies and the atmosphere. Gas exchange rates yield mean canopy air residence times ranging from minutes during turbulent daytime hours to greater than 12 h during calm nights. Rn is an effective tracer for net ecosystem exchange of CO2 (CO2 NEE) during calm, night‐time hours when eddy covariance‐based NEE measurements are less certain because of low atmospheric turbulence. Rn‐derived night‐time CO2 NEE (9.00±0.99 μmol m?2 s?1 in the wet season, 6.39±0.59 in the dry season) was significantly higher than raw uncorrected, eddy covariance‐derived CO2 NEE (5.96±0.51 wet season, 5.57±0.53 dry season), but agrees with corrected eddy covariance results (8.65±1.07 wet season, 6.56±0.73 dry season) derived by filtering out lower NEE values obtained during calm periods using independent meteorological criteria. The Rn CO2 results suggest that uncorrected eddy covariance values underestimate night‐time CO2 loss at this site. If generalizable to other sites, these observations indicate that previous reports of strong net CO2 uptake in Amazonian terra firme forest may be overestimated. 相似文献
8.
Radon survey in dwellings of Gansu,China: the influence of thoron and an attempt for correction 总被引:1,自引:0,他引:1
Alpha track detectors used in a previous investigation of the US National Cancer Institute and the China Ministry of Health on indoor radon ((222)Rn) in Gansu, China, proved to be influenced by (220)Rn (thoron), thus overestimating the (222)Rn level. Therefore, the detector was improved used in the previous survey. The new detectors allow discrimination between the two isotopes without any disturbance of the (222)Rn measurement. With this detector, a semi-annual study was conducted in 49 traditional dwellings of a village in Gansu. The arithmetic (AM) and geometric (GM) mean (222)Rn concentrations were 120 +/- 61 and 105 Bq m(-3) (with geometric standard deviation GSD = 1.8), respectively, while the mean (220)Rn concentrations at 2.5 cm wall distance were 430 +/- 210 Bq m(-3) (AM) and 350 Bq m(-3) (GM) with GSD = 2.3. The high thoron concentrations demonstrate the importance of the (220)Rn contribution to radiation exposure, in the investigated area. The actual level of indoor (222)Rn was about three times lower than that in the previous investigation which was affected by (220)Rn. A correction method for the radon results of the previous study is proposed, which provides (222)Rn and (220)Rn values comparable with those obtained in the study presented here. 相似文献
9.
We evaluated the nighttime CO2 flux (ecosystem respiration) on Rishiri Island, located at the northern tip of Hokkaido, Japan, from 2009 to 2011, by using the relationship between atmospheric 222Rn and CO2 concentrations. The annual mean CO2 flux was 1.8 μmol m?2 s?1, with a maximum monthly mean in July (4.6 ± 2.6 μmol m?2 s?1) and a broad minimum from December to March (0.33 ± 0.29 μmol m?2 s?1). The annual mean was comparable to fluxes at the JapanFlux sites in northern Japan. During the season of snow cover (mid-December to early April), the CO2 flux was low (0.45 ± 0.43 μmol m?2 s?1). Total annual respiration was estimated at 679 ± 174 g cm?2, about 8 % of which occurred during the season of snow cover. 相似文献
10.
Electron microscopy of denatured RNA of southern bean mosaic virus (SBMV) shows two principal linear components, 0.31 ± 0.08 μm (subgenomic RNAs, MW 0.51 × 106) and 0.80 ± 0.17 μm (genomic RNA, MW 1.3 × 106 25S). Nondenatured RNA (~ 32S) from heat-inactivated virions measure 1.0 ± 0.20 μm (MW 1.64 × 106) but is poorly-infectious. Upon denaturation the 325 RNA disaggregates into components of lengths typical of the genomic and subgenornic RNAs and infectivity is restored. 相似文献
11.
Great deal of work has been devoted to determine doses from alpha particles emitted by 222Rn and 220Rn progeny. In contrast, contribution of beta particles to total dose has been neglected by most of the authors. The present
work describes a study of the detriment of 222Rn and 220Rn progeny to the human lung due to beta particles. The dose conversion factor (DCF) was introduced to relate effective dose
and exposure to radon progeny; it is defined as effective dose per unit exposure to inhaled radon or thoron progeny. Doses
and DCFs were determined for beta radiation in sensitive layers of bronchi (BB) and bronchioles (bb), taking into account
inhaled 222Rn and 220Rn progeny deposited in mucus and cilia layer. The nuclei columnar secretory and short basal cells were considered to be sensitive
target layers. For dose calculation, electron-absorbed fractions (AFs) in the sensitive layers of the BB and bb regions were
used. Activities in the fast and slow mucus of the BB and bb regions were obtained using the LUNGDOSE software developed earlier.
Calculated DCFs due to beta radiation were 0.21 mSv/WLM for 222Rn and 0.06 mSv/WLM for 220Rn progeny. In addition, the influence of Jacobi room parameters on DCFs was investigated, and it was shown that DCFs vary
with these parameters by up to 50%. 相似文献
12.
Seasonal and long-term variation of the airborne 212Pb concentration, representative of the equilibrium equivalent concentration of thoron decay products (EECRn220), was investigated from 1989 through 1996 at a semi-natural location in southern Germany. Continuous measurement yielded
a long-term average concentration of 0.082 Bq m–3, while daily mean concentrations varied from ≤0.01 to 0.34 Bq m–3. An average annual effective dose of 1.4 mSv due to outdoor thoron progeny concen-tration was estimated. This is about 2%
of the dose due to the average short-lived radon progeny concentration (EECRn222) of 8.4 Bq m–3 measured for this location in the same period. In most years the seasonal pattern of 212Pb activity concentration in the atmosphere is characterized by two maxima: the first in May and the second one in September.
Low concentrations are observed from November through February of each year. This is in contrast to the behaviour of the short-lived
222Rn progeny which exhibit enhanced concentrations exactly during these months. The most probable reason for the different temporal
behaviour of 212Pb is the extremely reduced flux of thoron gas from the ground during the winter months.
Received: 19 August 1997 / Accepted in revised form: 22 January 1998 相似文献
13.
V. M. Markovic D. Krstic D. Nikezic N. Stevanovic 《Radiation and environmental biophysics》2012,51(4):391-397
Great deal of work has been devoted to determine doses from alpha particles emitted by 222Rn and its progeny. In contrast, contribution of beta particles and following gamma radiation to total dose has mostly been neglected so far. The present work describes a study of the detriment of 222Rn progeny for humans due to external exposure. Doses and dose conversion factors (DCFs) were determined for beta and gamma radiation in main organs and remainder tissue of the Oak Ridge National Laboratory phantom, taking into account 222Rn progeny 214Pb and 214Bi distributed in the middle of a standard or typical room with dimensions 4?m?×?5?m?×?2.8?m. The DCF was found to be 7.37?μSv/WLM. Skin and muscle tissue from remainder tissue receives largest dose. Beta and gamma radiation doses from external exposure were compared with alpha, beta, and gamma doses from internal exposure where the source of radioactivity was the lungs. Total doses received in all main organs and remainder tissues were obtained by summing up the doses from external and internal exposure and the corresponding DCF was found to be 20.67?μSv/WLM. 相似文献
14.
M. A. Misdaq M. Ghilane J. Ouguidi K. Outeqablit 《Radiation and environmental biophysics》2012,51(4):375-389
In Morocco, thermal waters have been used for decades for the treatment of various diseases. To explore the exposure pathway of 238U, 232Th and 222Rn to the skin of bathers from the immersion in thermal waters, these radionuclides were measured inside waters collected from different Moroccan thermal springs, by means of CR-39 and LR-115 type II solid-state nuclear track detectors (SSNTDs), and corresponding annual committed effective doses to skin were determined. Accordingly, to assess radiation dose due to radon short-lived decay products from the inhalation of air by individuals, concentrations of these radionuclides were measured in indoor air of two thermal stations by evaluating mean critical angles of etching of the CR-39 and LR-115 II SSNTDs. Committed effective doses due to the short-lived radon decay products 218Po and 214Po by bathers and working personnel inside the thermal stations studied were determined. 相似文献
15.
Mehdi Fazlzadeh Roohollah Rostami Abbas Norouzian Baghani Adel Mokammel 《人类与生态风险评估》2018,24(6):1441-1452
This study aimed to assess hydrogen sulfide (H2S) concentrations in the pool indoor air of hot springs and its link to some physicochemical properties of the springs in Ardabil province. Twenty-two hot springs from different regions were selected and monitored for H2S concentrations using a portable gas meter. Respective mean concentrations of H2S in hot springs indoor air were 9.11 ± 11. Ghotour Souei hot springs had the highest concentration of H2S with a mean concentration of 29.4 ± 7.7 and 25.2 ± 8.16 ppm at the source and general pool areas, respectively. Oxidation-reduction potential and pH of the water were the most important factor influencing H2S concentrations in the hot springs. H2S concentrations in indoor air of Ardabil hot springs were noticeably higher than OEL-TWA and OEL-STEL, and therefore may pose important risks for human health on both short-and long-term exposures. 相似文献
16.
Summary The paper presents results of measurements made on cereals and composite meal samples collected from Bombay market for their lead-210 content. The details of sampling and analytical chemistry procedures are also given. The Pb-210 contents of most of these samples were in the range of 1–5 pCi/kg of cereals samples. The concentrations in composite meal samples were mostly in the range of 1–3.5 pCi of210Pb per composite meal. The assessment of daily intake of this isotope through food-stuffs has been made. 相似文献
17.
18.
In 1989–1990 and 1997, in the Bay of Izmena (Kunashir Island), the spatial distribution ofAhnfeltia tobuchiensis (Kanno et Matsubara) Mak, an unattached agar-containing red alga, was studied, and the availability of biogenic elements
for the process ofA. tobuchiensis primary production was assessed. The concentrations of dissolved O2, ammonium [NH
4
+
], and orthophosphate [PO
4
3−
], were highest in the central and northeastern areas of the bay, where the bulk of the population is situated. During the
day, the mean oxygen concentration above the alga bed increased from 8.2±0.09 to 8.7±0.08 mg/l, showing a high rate of photosynthesis
in the population. As a result of diurnal ammonium and orthophosphate assimilation by the alga, their concentration in bottom
waters dropped from 5.1 to 3.5 and from 0.45 to 0.35 μM/l, respectively. Proceeding from the mean values of the nitrogen to
phosphorus atomic ratio in the bay waters (11.5±3.3 in the morning and 10.6±3.3 in the evening) and in algal thalluses (33
in the case ofA. tobuchiensis), we conclude that the concentration of major biogenic elements is sufficient for the processes of primary production in
the Bay of Izmena. 相似文献
19.
For the determination of airborne radionuclide concentrations in real time, a fixed filter device was constructed which fits directly onto a germanium detector with standard nuclear electronics and a multichannel analyzer buffer connected via a data line to a personal computer for remote control and on-line spectrum evaluation. The on-line gamma-ray spectrometer was applied to the study of radon decay product concentrations in ground-level air and to the rapid detection of any contamination of the environmental air by artificial radionuclides. At Munich-Neuherberg, depending on the meteorological conditions, the measured air concentrations of214Pb, the first gamma-ray-emitting member of the222Rn decay series, varied from about 1 to 50 Bq m–3. For the artifical radionuclides60Co,131I and137Cs the detection limits were determined as a function of the varying natural radon daughter concentrations at sampling and counting times of 1 h or 1 day. For these radionuclides minimum detectable air activity concentrations of 0.3 or 0.001 Bq m–3, respectively, were obtained at low radon daughter levels. At high radon daughter levels the respective detection limits were found to be higher by a factor of only about 2.Dedicated to Prof. Wolfgang Jacobi on the occasion of his 65th birthday 相似文献
20.
The virulence of the DAT F-001 isolate ofMetarhizium anisopliae forAdoryphorus couloni was tested by exposing final instar larvae (L3) to concentrations of 101 to 107 spores/g in a sand-peat mix for up to 112 days at 20°±2°C. All concentrations were pathogenic to L3 larvae and survival was
dependent on concentration and correlated with exposure time. The time to kill 50% of the treated larvae (LT50) ranged from 18.9 days (107 spores/g) to 82.7 days (101 spores/g). The effect of DAT F-001 on feeding by L3 larvae was determined by comparing the production and weight of frass
pellets/larva/day of untreated control larvae with larvae rolled in sporulating cultures ofM. anisopliae DAT F-001 and DAT F-054 (low virulence). Exposure to, and infection byM. anisopliae DAT F-001 had minimal impact on larval feeding. L3 larvae continued to feed at the same rate as both untreated and DAT F-054
treated larvae virtually until they died.
Résumé La virulence deM. anisopliae DAT F-001 pourA. couloni a été analysée en exposant des larves L3 à des concentrations de 101 à 107 spores/g dans un mélange de sable et de tourbe pendant un maximum de 112 jours à une température de 20°±2°C. Toutes les concentrations sont pathogènes pour les larves L3; la survie dépendait de la concentration et est en corrélation avec le temps d'exposition. Les LT50 sont compris entre 18,9 jours (107 spores/g) et 82,7 jours (101 spores/g). L'effet de DAT F-001 sur l'alimentation des larves L3 a été évalué en comparant la production et le poids des fèces/larve/jour des larves non-traitées avec des larves roulées dans des cultures sporulées deM. anisopliae DAT F-001 et DAT F-054 (faible virulence). L'exposition àM. anisopliae DAT F-001 suivie de l'infection a peu d'effet sur l'alimentation des larves. Les larves L3 continuent à s'alimenter au même rythme que les larves non-traitées de DAT F-054, quasiment jusqu'à leur mort.相似文献