首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 62 毫秒
1.
Artificial radionuclides, such as iodine-131 (131I), cesium-134 (134Cs), and cesium-137 (137Cs), as well as natural isotopes of beryllium-7 (7Be) and potassium-40 (40K) have been registered in atmospheric aerosols over Vladivostok selected from 11 March to 17 June 2011. Additionally, 134Cs and 137Cs were detected in atmospheric aerosols over Tomsk selected from 16 March to 17 June 2011. Artificial radionuclides were also discovered in atmospheric wet depositions sampled in Vladivostok from 3 to 17 May 2011. Moreover, these radionuclides have been registered in atmospheric aerosols over the sea surface of the Sea of Japan selected from 3 to 31 May 2011 during an expedition of the “Nadezhda” sailing ship. From 18 March to 15 April, an increase in concentrations of atmospheric aerosols over Vladivostok from 108.8 to 321.5 μg/m3 has been registered. It was accompanied by increased activity concentrations of 134Cs, 137Cs, and the 131I. During the period from 18 March to 15 April, activity concentrations of 137Cs and 134Cs in atmospheric aerosols increased 100 times compared with the minimum detectable concentration (MDC) level and peaked in the weekly sample gathered from 8 to 15 April (145.0 and 105.3 μBq/m3, respectively). Variability of concentrations of natural isotopes of 7Be and 40K was not greater than 1 order of magnitude throughout the sampling period. Maximal values of 137Cs and 134Cs concentrations (1,281.5?±?141 and 384.4?±?42.3 μBq/m3, respectively) in Tomsk were reached in samples taken from 1 to 2 April. For the atmospheric aerosol samples from the Sea of Japan, the largest concentration of 131I (392.3?±?215.7 μBq/m3) was detected from 13 to 19 May, while all other samples had much lower concentration values. Synoptic analysis of back trajectories movement of air masses showed that the radioactive cloud came to Vladivostok from the regions of Siberia and northeastern part of China. Synoptic analysis for Tomsk showed that during the period of maximal activity concentrations (1–9 April), air masses were arriving from the European part of Russia and north of Kazakhstan.  相似文献   

2.
On 28 and 29 November 2005, the tropical storm Delta struck the Canary Islands (Spain) and the western shores of Morocco. Gravimetric and radiometric measurements carried out in atmospheric aerosol and water samples, collected after the storm, showed increased levels of total suspended particles (TSP) in the atmosphere and gross alpha, gross beta as well as 90Sr activities in both the atmosphere and drinking water. These variations were most likely produced by local re-suspension of soil material. However, 210Pb and 7Be activities, measured in atmospheric aerosols, did not increase until a week after the storm had passed. 40K and 137Cs activities, also measured in atmospheric aerosols, did not vary significantly with respect to previous weeks indicating that the slightly higher levels of TSP, measured during the week when the storm occurred, were not produced by the long-range transport of re-suspended aerosols from the African continent, as it has been observed in other occasions at this site. Gross alpha, gross beta, 40K and 90Sr levels in drinking water samples increased after the storm over their average values by approximately 245%, 245%, 130% and 440%, respectively. These results indicate how important the local re-suspension and later deposition/scavenging of aerosols may be on the water supply in Tenerife.  相似文献   

3.
The seasonal variation of the 210Po/210Pb activity ratio in aerosols, as a function of particle size, have been studied at Kamo, on the west coast of Japan from July 1995 to June 1996. It was shown that 70% of 210Po and 77% of 210Pb activities were measured in aerosols with a diameter smaller than 0.7 μm. On the other hand, the abundances of 210Po and 210Pb in aerosols with a diameter larger than 10.9 μm were 3 and 1%, respectively. In general, the maxima of the 210Po/210Pb ratio were observed in aerosols of 5.4–10.9 μm, but the maxima in January and April 1996 appeared in the largest and the smallest size fractions, respectively. The results suggest that the size distribution of the 210Po/210Pb activity ratio may be modified by changes in the nature and intensity of aerosol sources.  相似文献   

4.
During a one-year period, from November 1998 upto October 1999, the atmospheric activity concentrations of the short-lived (222Rn)-progeny (218Po, 214Pb, 214Po) were measured every 4 h in the open air, using α-spectrometry. The concentration data of short-lived radon progeny together with meteorological variables (relative humidity, air temperature, and wind speed) were used for a comprehensive regression analysis of daily time variation of radioactivity in the air. The seasonal concentration pattern of all short-lived radon progeny shows the same trend for diurnal variation with higher values at night and early morning hours compared with lower values at noon and in afternoon. The activity concentrations were observed to be higher during the winter months (November–January) than in other seasons. The mean activity concentrations of 218Po, 214Pb and 214Po within the whole year were found to be 6.7±0.8, 4.9±0.5 and 4.4±0.3 Bq m−3, respectively.Also, within that time period, approximately 120 samples were analysed to determine the concentrations of the long-lived radon decay product 210Pb and the cosmogenic radionuclide 7Be using a single-filter technique. The course of 210Pb air concentration is characterized by higher values in autumn/winter season and lower values in spring/summer season. The seasonal concentration pattern of 7Be reaches regular maximum values in the spring to early summer months. The annual average concentration values of 210Pb and 7Be have been found to be 0.37±0.06 and 2.0±0.09 mBq m−3, respectively. A mean aerosol mass concentration of 36.6±6.2 μg m−3 was also determined during the measurements of the long-lived radionuclides. The majority of attached 210Pb and 7Be were observed at lower aerosol mass concentrations while small fractions of attached activities were found to be associated with the higher mass concentrations.  相似文献   

5.
The activity of the natural radionuclide tracers 7Be and 210Pb has been determined in bulk aerosol samples collected over 2-day intervals for nearly five full years at Summit, Greenland. Year-round sampling was conducted in three campaigns; summer 1997 to summer 1998, summer 2000 to summer 2002, and summer 2003 to present. As in previous summer campaigns at Summit, and a year-round investigation at Dye 3, variations in the activities of the tracers on short time scales were strongly correlated despite the upper troposphere/lower stratosphere source of 7Be and the continental surface source of 222Rn (precursor of 210Pb). This behavior is attributed to boundary layer dynamics exerting the dominant control on activities in air just above the ice sheet. Aerosols and associated species are depleted from the boundary layer above the snow when a strong inversion limits exchange with the free troposphere. Episodic weakening of the inversion allows ventilation of the boundary layer. This cycle drives simultaneous decreases and increases in the radionuclide tracers. The correlation between 7Be and 210Pb on seasonal and annual bases was found to be stronger than at Dye 3, and the average activity of 7Be was lower at Summit despite the higher elevation (3.0 versus 2.5 km). These observations indicate that the boundary layer at Summit is more effectively isolated than at Dye 3. The activity of 7Be at Summit peaked in June or July all 5 years, closely following the seasonality of stratospheric injection of 7Be into the Arctic troposphere (based on seasonality of the 10Be/7Be ratio previously measured at Alert, NWT). This suggests that when the boundary layer at Summit is replenished by ventilation, it receives air reflecting the composition of the mid and upper troposphere.  相似文献   

6.
Environmental Science and Pollution Research - A study was carried out to determine the activities of radionuclides (137Cs, 40K, 226Ra, 214Bi, 214Pb, and 210Pb) and the levels of biochemical...  相似文献   

7.
Radionuclide concentration analysis of total moss bodies often gave relatively different results than a separate analysis of each different morphological part of the same sample. The dynamics of the transfer of metals by dust uplifted from the soil and another approach, based on the diffusion of the two radionuclides to the moss, have been analyzed. In the proposed model, short- and long-term approaches have been applied. Each part of a moss’s profile can show different radionuclides accumulation ability, including both 210Pb and 210Po isotopes. A first-order kinetic model has been used for 210Po and 210Pb transport between three body components of mosses. This mathematical approach has been applied for 210Po activity concentration in the air estimation. For relatively clean deep forest region, calculated concentrations were from 17.2 to 43.8 μBqm?3, while for urban air concentrations were higher from 49.1 to 104.9 μBqm?3.  相似文献   

8.
As an indicator of environmental pollution, we collected tree rings and bark of linden (Tilia platyphyllos Scop.) from four sampling locations in Serbia. Mn and Pb were determined with a spectrochemical method that has an argon-stabilized U-shaped DC arc with aerosol supply as excitation source. Increased concentrations of Mn in linden tree rings and bark were found at the Debeli Lug location, where the Mn transfer factors were largest. The availability of Mn in soil and tree rings was greatly influenced by pH. Since 1950, Mn level decreased more noticeably on acidic soils. Higher concentrations of Pb were found in linden tree rings and bark at the locations Fru?ka Gora and Zemun. Proximity of the road to Novi Sad at both sites may be a possible reason for this. The Pb transfer factor was highest at Fru?ka Gora. The ratio of bioavailable elements in soil for Mn and Pb were also calculated. Close correlations between Mn and Pb concentrations in linden tree rings and the ratio of bioavailable elements in soil were seen at all four locations.  相似文献   

9.
The present study focuses on the exceptional Saharan dust event that affected most of France in February 2004. Activity levels of various artificial radionuclides (90Sr, 137Cs, uranium, thorium and plutonium isotopes, 241Am) were examined. Activity or isotopic ratios are discussed in the context of atmospheric nuclear weapons tests, among them French tests performed in Sahara in the 1960s. The daily evolution of 137Cs activity levels in the atmosphere was compared to daily PM10 change. A link between airborne 137Cs and PM10, is given. It is estimated that this 2-day event deposited as much 137Cs as would be deposited on average over a 10-month period. The amount of deposited 137Cs and 239+240Pu represents respectively about 0.1 and 1% of the activity already present in the soil. Such Saharan dust events correspond to an extreme type of “feeder” process of artificial radionuclides in the atmosphere. Therefore, they contribute to the long term background level of artificial radionuclides kept at trace levels in the atmosphere.  相似文献   

10.
《Chemosphere》2002,49(10)
The distribution coefficients (Kd) and desorption rates of 137Cs and 241Am radionuclides in bottom sediments at different locations in the Black Sea were studied under laboratory conditions. The Kd values were found to be 500 for 137Cs and 3800 for 241Am at the steady state and described exponential curves. Rapid uptake of the radionuclides occurred during the initial period and little accumulation happened after four days. The desorption rates for 137Cs in different bottom sediments were best described by a three-component exponential model. The desorption half-times of 137Cs ranged from 26 to 50 d at the slow components. However, the desorption rate of 241Am described one component for all sediment samples and desorption half-time was found to be 75 d. In general, the results showed that the 241Am radionuclide is more effectively transferred to bottom sediment and has longer turnover time than 137Cs under Black Sea conditions.  相似文献   

11.
Several environmental media in Austria were monitored for artificial radionuclides released during the Fukushima nuclear accident. Air (up to 1.2 mBq/m3 particulate 131I) and rainwater (up to 5.2 Bq/L 131I) proved to be the media best suited for the environmental monitoring, allowing also a temporal resolution of the activity levels. Significant regional differences in the wet deposition of 131I with rain could be observed within the city of Vienna during the arrival of the contaminated air masses. Forward-trajectory analysis supported the hypothesis that the contaminated air masses coming from the northwest changed direction to northeast over Northern Austria, leading to a strong activity concentration gradient over Vienna. In the course of the environmental monitoring of the Fukushima releases, this phenomenon—significant differences of 131I activity concentrations in rainwater on a narrow local scale (8.1 km)—appears to be unique. Vegetation (grass) was contaminated with 131I and/or 137Cs at a low level. Soil (up to 22 Bq/kg 137Cs) was only affected by previous releases (nuclear weapon tests, Chernobyl). Here, also significant local differences can be observed due to different deposition rates during the Chernobyl accident. The effective ecological half-lives of 137Cs in soil were calculated for four locations in Austria. They range from 7 to 30 years. No Austrian sample investigated herein exceeded the detection limit for 134Cs; hence, the Fukushima nuclear accident did not contribute significantly to the total radiocesium inventory in Austrian environmental media. The levels of detected radioactivity were of no concern for public health.  相似文献   

12.
In this paper the time evolution of heavy metal concentration of Pb, Zn, Cd and Hg, in the sediments of the Bay of Cádiz (southwest of Spain) is studied during the past century, as a result of the industrial influence in the zone. The study has been performed using sedimentary profiles that have been extracted from the seabed. The measurement of 210Pb and 137Cs radionuclides has provided the dating of the sediment layers, up to a depth corresponding to the age of 115 years. The relative sedimentation rates obtained are around 0.2 cm/year. The 137Cs activity profile reflects the concentration of this radionuclide in the atmosphere and into aquatic systems during the second half of the twentieth century. This profile has been used to ratify the results provided by the 210Pb dating method.  相似文献   

13.
Although it occurred nearly 50 years ago, the nuclear reactor fire of October 1957 at Windscale Works, Sellafield, England, continues to attract interest. Several attempts have been made to quantify the releases of radionuclides and their radiological consequences, but additional information and a re-analysis of meteorological data encourage a further examination of emissions. The limited instrumentation of the reactor provided little relevant information and, as in previous estimates, the discharges are deduced from environmental evidence, but here the recent meteorological analysis is used. The interpretation of the meteorological and environmental evidence requires both timing and quantity of the emitted radionuclides to be considered together.Significant fission product emission continued from about 15:00 or 16:00 on 10 October 1957 until noon the following day. There were two main peaks in discharge rate, during the evening and early hours and from roughly 06:00 until 10:30, and the amounts emitted during each of these periods were probably comparable.Iodine-131 (131I), caesium-137 (137Cs) and polonium-210 (210Po) activities dominated the radioactive emissions and there is sufficient environmental evidence for releases of these radionuclides to be estimated within a factor of about two. (Some additional 131I may have escaped in a chemical form that was not included in the estimate, but it appears likely that the fraction was small.) There is evidence that the plume extended further east than accepted in previous assessments and the estimates of quantities emitted have been increased to allow for this. For other radionuclides the environmental measurements were fewer and the uncertainties are greater.  相似文献   

14.
One question in the use of plants as biomonitors for atmospheric mercury (Hg) is to confirm the linear relationships of Hg concentrations between air and leaves. To explore the origin of Hg in the vegetable and grass leaves, open top chambers (OTCs) experiment was conducted to study the relationships of Hg concentrations between air and leaves of lettuce (Lactuca sativa L.), radish (Raphanus sativus L.), alfalfa (Medicago sativa L.) and ryegrass (Lolium perenne L.). The influence of Hg in soil on Hg accumulation in leaves was studied simultaneously by soil Hg-enriched experiment. Hg concentrations in grass and vegetable leaves and roots were measured in both experiments. Results from OTCs experiment showed that Hg concentrations in leaves of the four species were significantly positively correlated with those in air during the growth time (p?<?0.05), while results from soil Hg-enriched experiment indicated that soil-borne Hg had significant influence on Hg accumulation in the roots of each plant (p?<?0.05), and some influence on vegetable leaves (p?<?0.05), but no significant influence on Hg accumulation in grass leaves (p?>?0.05). Thus, Hg in grass leaves is mainly originated from the atmosphere, and grass leaves are more suitable as potential biomonitors for atmospheric Hg pollution. The effect detection limits (EDLs) for the leaves of alfalfa and ryegrass were 15.1 and 22.2 ng g–1, respectively, and the biological detection limit (BDL) for alfalfa and ryegrass was 3.4 ng m–3.  相似文献   

15.
Hu X  Zhang Y  Luo J  Xie M  Wang T  Lian H 《Chemosphere》2011,82(10):1351-1357
Foliar uptake of airborne lead is one of the pathways for Pb accumulation in plant organs. However, the approximate contributions of airborne Pb to plant organs are still unclear. In the present study, aerosols (nine-stage size-segregated aerosols and total suspended particulates), a wild plant species (Aster subulatus) and the corresponding soils were collected and Pb contents and isotopic ratios in these samples were analyzed. Average concentration of Pb was 96.5 ± 63.5 ng m−3 in total suspended particulates (TSP) and 20.4 ± 5.5 ng m−3 in the fine fractions of size-segregated aerosols (SSA) (<2.1 μm), higher than that in the coarser fractions (>2.1 μm) (6.38 ± 3.71 ng m−3). Enrichment factors show that aerosols and soils suffered from anthropogenic inputs and the fine fractions of the size-segregated aerosols enriched more Pb than the coarse fractions. The order of Pb contents in A. subulatus was roots > leaves > stems. The linear relationship of Pb isotope ratios (206Pb/207Pb and 208Pb/206Pb) among soil, plant and aerosol samples were found. Based on the simple binary Pb isotopic model using the mean 206Pb/207Pb ratios in TSP and in SSA, the approximate contributions of airborne Pb into plant leaves were 72.2% and 65.1%, respectively, suggesting that airborne Pb is the most important source for the Pb accumulation in leaves. So the combination of Pb isotope tracing and the simple binary Pb isotope model can assess the contribution of airborne Pb into plant leaves and may be of interest for risk assessment of the exposure to airborne Pb contamination.  相似文献   

16.
Study of the vertical concentration profile and of the deposition of cosmogenic radionuclides provides information on the vertical transport in the stratosphere and troposphere and the processes of scavenging of aerosol particles by precipitation. Information on the distribution of atmospheric aerosols is important for the understanding of the physical processes relating to the studies in weather climate, air pollution, and aerosol physics. In this work the one-dimensional steady-state model of vertical concentration profile was established and the values of turbulent diffusion coefficient and scavenging coefficient determined by model using experimental data of the 7Be monthly average atmospheric activity concentrations and monthly deposition fluxes in Bratislava are presented. The temporal variations of the vertical distribution profiles of 7Be for each month are also calculated.  相似文献   

17.
The city of Aldama, Chihuahua, Mexico is located 30 km NNE of Chihuahua city. Three high-volume collectors with PM10 heads were placed in specific locations in Aldama during the year 2011 to measure radioisotope concentrations in the air. The city area of 16 km2 was divided into 64 squares of 500 × 500 m. At the vertices of the grid, silt samples were taken between January and June 2011, before the rains began. The concentrations of natural, cosmogenic, and anthropogenic radioactive isotopes were calculated in both filters and silts samples. The isotopes selected for the measurement were 238U, 232Th, 7Be, 137Cs, and 40K. Measurements of PM10 and silts were performed during 2011, coinciding with the accident at Fukushima, Japan, on March 11. For this reason, we could see the 137Cs in PM10 increase between April and July; with the arrival of the rains, the 137Cs concentration began to decrease in the air. The concentration of PM10 measured by the equipment located at the Mexican Uranium plant (URAMEX, initials in Spanish) that was processing radioactive ores exceeded the standard values in February and March, when the air velocity increases. At City Hall, the concentration of PM10 surpassed the value of the standard between May and July. This increased concentration is likely due to increased automobile traffic because City Hall is located in the city center. At a private home, the concentration of PM10 surpassed the standard on several days during the year because the home is located on the outskirts of the city, where most of the streets are not paved. Due to the high concentrations of PM10, especially at the collection point located at the private home, it is necessary to start taking steps to mitigate their spread before they cause health problems in the younger population and in older adults.

Implications: The radioisotope content found in the PM10 confirms that the decision to place the Mexican Uranium plant (URAMEX, initials in Spanish) processing radioactive ores near the town of Aldama was not well thought out. Because the monitoring work was carried out in 2011 and coincided with the Fukushima accident, an increased concentration of 137Cs could be detected in the PM10. We made recommendations to the municipal authorities of the city to mitigate the concentration of particles in the air.  相似文献   

18.
In long-term safety assessment models for radioactive waste disposal, uptake of radionuclides by plants is an important process with possible adverse effects in ecosystems. Cobalt-60, 59,63Ni, 93Mo, and 210Pb are examples of long-living radionuclides present in nuclear waste. The soil-to-plant transfer of stable cobalt, nickel, molybdenum and lead and their distribution across plant parts were investigated in blueberry (Vaccinium myrtillus), May lily (Maianthemum bifolium), narrow buckler fern (Dryopteris carthusiana), rowan (Sorbus aucuparia) and Norway spruce (Picea abies) at two boreal forest sites in Eastern Finland. The concentrations of all of the studied elements were higher in roots than in above-ground plant parts showing that different concentration ratios (CR values) are needed for modelling the transfer to roots and stems/leaves. Some significant differences in CR values were found in comparisons of different plant species and of the same species grown at different sites. However, large within-species variation suggests that it is not justified to use different CR values for modelling soil-to-plant transfer of these elements in the different boreal forest plant species.  相似文献   

19.
The nuclear accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) which occurred after the Great East Japan Earthquake on March 11, 2011 resulted in releases of radionuclides such as 134Cs (half-life:T1/2 = 2.06 yr), 137Cs (T1/2 = 30.04 yr) and 131I (T1/2 = 8.05 d) to the environment. For this paper, we observed the monthly variations of radiocesium (134Cs and 137Cs) and stable Cs concentrations in influent, effluent, sewage sludge, and sludge ash collected from a sewage treatment plant 280 km north of the FDNPP from July to December, 2011. Using the stable Cs results, we concluded the mass balance of Cs in the sewage treatment plant showed that about 10% of the Cs entering the sewage treatment plant would be transferred to the sewage sludge, and then Cs in the sewage sludge was totally recovered in the sludge ash. The behavior of Cs was similar to that of Rb, but it was not similar to that of K in the sewage treatment process.  相似文献   

20.
Edible and medicinal macrofungi used in human diet represent not only important sources of nutritive elements but toxic substances as well (heavy metals and radionuclides). Radioactivity levels of four radionuclides (40K, 137Cs, 226Ra, 228Ra) were determined in the basidiomata (fruiting bodies of a Basidiomycetes) of six lignicolous (Fomitopsis pinicola, Ganoderma applanatum, Hericium clathroides, Megacollybia platyphylla, Pluteus cervinus, Trametes gibbosa) and three mycorrhizal (Boletus luridus, Boletus sp. 1, Boletus sp. 2) species as well as their soil (wood) substrates by gamma spectrometry (high-resolution high-purity germanium (HPGe) detector). The aim was to investigate their ability for radionuclide absorption according to transfer factors (from soil and wood), to predict potential bioindicator species as well as species with potential risk for human use. Samples were taken during years 2011 and 2012, at two sites in forest ecosystem of Tara Mountain (Serbia). Observed concentration ranges per dry weight were as follows: 29–3,020 Bq/kg (40K), 21.9–735 Bq/kg (137Cs), 3–39 Bq/kg (226Ra), and 2.0–18 Bq/kg (228Ra). Obtained results indicate that the type of basidiome (fleshy/tough), most likely due to a different metabolic rate, has a very important role in radionuclide accumulation. The highest activity concentrations of all analyzed radionuclides were found in species with fleshy basidiomata—P. cervinus, H. clathroides, M. platyphylla, and Boletus species. A species-specific influence on radionuclide uptake was more prominent comparing to habitat differences and the role of fungal trophic mode. No significant variations were observed regarding radionuclide activity among the same fungal species from different sampling sites.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号