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1.
This study reports distribution of uranium (U) and thorium (Th) in soil samples and the roots and shoots of some plants grown around an abandoned lead (Pb)–zinc (Zn)–copper (Cu) mining area. The plants Euphorbia macroclada, Verbascum cheiranthifolium Boiss, and Astragalus gummifer were examined. The determinations of U and Th were carried out by inductively coupled plasma‐mass spectrometry (ICP‐MS). Uranium and Th levels of the studied soil samples were found to be in the range of 1.1–70.3 mg kg?1 and 2.1–62.1 mg kg?1, respectively. Some results obtained from this study were higher than the mean U and Th concentrations of soils reported around the world. Uranium and thorium concentrations in studied plant roots were in the range of 0.04–16 and 0.08–14.57 mg kg?1, whereas in plant shoots they were 0.02–2.76 and 0.07–12.3 mg kg?1, respectively. It was concluded that the shoots of Astragalus and roots of Euphorbia and Verbascum can be used as both a biomonitor for environmental pollution and biogeochemical indicator because of their higher U and Th concentrations.  相似文献   

2.
Air pollution can be a problem in industrial processes, but monitoring and controling the aerosols in the work place is not enough to estimate the occupational risk due to dust particle inhalation. The solubility in lung fluid is considered to estimate this risk. The aim of this study is to determine in vitro specific dissolution parameters for thorium (Th), uranium (U), and tantalum (Ta) associated to crystal lattice of a niobium mineral (pyrochlore). Th, U, and Ta dissolution factors in vitro were obtained using the Gamble solution (simulant lung fluid, SLF), particle induced X-ray emission, and alpha spectrometry as analytical techniques. Ta, Th, and U are present in the pyrochlore crystal lattice as oxide; however, they have shown different dissolution parameters. The rapid dissolution fraction (f r), rapid dissolution rate (λ r), slow dissolution rate (f s), and slow dissolution fraction (λ s) measured for tantalum oxide were equal to 0.1 and 0.45 and 0.00007 day?1, respectively. For uranium oxide, f r was equal to 0.05, λ r was equal to 1.1 day?1, and λ s was equal to 0.000068 day?1. For thorium oxide, f r was 0.025, λ r was 1.5 day?1, and λ s was 0.000065 day?1. These results show that chemical behavior of these three compounds in the SLF could not be represented by the same parameter. The ratio of uranium concentration in urine and feces samples from workers exposed to pyrochlore dust particle was determined. These values agree with the theoretical values of estimated uranium concentration using specific parameters for uranium oxide present in pyrochlore.  相似文献   

3.
In a study to differentiate between coal-fly ash and minerals in the atmosphere, samples were collected on Nuclepore filters in dichotomous samplers and analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry. The samples included ambient aerosol from two sites, resuspended soil, and emissions from coal- and oil-fired power plants in the Philadelphia area. Fly ash and minerals were identified by observing high abundances of Al, Si, K, Ca, Ti, and Fe in individual particles, and their mass concentrations were estimated from measured dimensions and an assumed density. Fly ash was distinguished from minerals by morphology. Sulfate was the major component of the fine fraction (<2.5 μm aerodynamic dia.). Crustal matter concentrations in the fine fraction estimated by SEM ranged from 40 to 300 ng m?3, and fly ash accounted for 7 to 62% of the crustal matter. In the coarse fraction (2.5 to 10 μm), minerals were the predominant component and ranged in concentration from 500 to 6000 ng m?3. Fly ash accounted for 0 to 16% of the crustal matter; the typical amount was 6%. Other less abundant coarse particles included botanical matter and industrial source emissions. Coarse fraction crustal matter estimated from x-ray fluorescence elemental data agreed well with that based on electron microscopy.  相似文献   

4.
Abstract

Concentrations of uranium and thorium have been determined for samples of soil from 860 locations in 30 provinces throughout the China. Elevated levels of uranium, thorium, and Th/U as compared with the average world abundance in earth crust were observed. Furthermore, variation of uranium and thorium concentrations with soil types from north towards south China indicates a geochemical weathering pattern and leaching effect on soil development.  相似文献   

5.
Abstract

Neutron Activation Analysis (NAA) was used for the determination of metal concentrations of sediments sampled at specific locations of the Kubanni River in Nigeria. The sedimentation process was assessed by examining the variation of the concentrations of the metals in different cores with sediment depths. Fifteen metals: arsenic (As), cerium (Ce), europium (Eu), iron (Fe), gadolinium (Gd), hafnium (Hf), holmium (Ho), potassium (K), lanthanum (La), lutetium (Lu), samarium (Sm), scandium (Sc), thorium (Th), uranium (U), and ytterbium (Yb) were detected from the sediments in substantial concentrations; higher than the parts per million (μg g‐1) value in some cases. Our results showed contamination of the surface sediments by U and Th, suggesting contributions from phosphate fertilizers used in farmlands around the basin as potential sources of these pollutants. Aeolian depositions emanating from the uranium‐rich region of Air (Niger) in the Saharan desert were considered to be other possibilities.  相似文献   

6.
The aim of this study is to determine the solubility rate of tantalum contained in pyrochlore, columbite–tantalite and columbite in simulant lung fluid. The International Commission on Radiological Protection (ICRP), in its recommendation for limiting intakes of radionuclide by workers, has consistently recognized that the biological behavior of any specific material after incorporation can significantly diverge from model prevision. Model parameters should be adjusted to adapt the model for each specific substance material in order to estimate the dose due to this element intake. The most recent ICRP publication 66, respiratory tract dosimetry model, point out that information as data like particle size, aerosols solubility and the material chemical compounds are important parameters in the dose coefficients calculation. This paper studies the solubility in Simulant Lung Fluid (SLF) of Ta present in mineral dust particles. For this study 3 minerals were selected: pyrochlore, columbite–tantalite and columbite. Tantalum dissolution in vitro samples were obtained using the Gamble solution and PIXE (Particle Induced X-ray Emission) as analytical technique. In order to characterize the worker exposure to Ta bearing particles, one Brazilian niobium mine was selected. The mineral dust particles were collected using a six-stage cascade impactor and the elemental mass concentrations and the MMAD (Mass Median Aerodynamic Diameter) were determined. Concentrations of radionuclides from natural series of thorium and uranium were also determined. The results show that the workers are exposed to Ta bearing particles in the respirable fraction of aerosols (aerodynamic diameter (d aer) <2.5 μm) during the mineral processing to obtain Fe–Nb alloy. The solubility in Simulant Lung Fluid (SLF) of Ta present in mineral dust particles depends on the mineral characteristics. The solubility half-time varies between 34 and 62 h depending on the associated mineral.  相似文献   

7.
Low-volume samplers collecting ambient aerosols in two size fractions have been used to collect radioactivity from the Chernobyl accident. The samplers were situated near light-houses on the east coast of Sweden and samples were collected during consecutive 12-hr periods. Activity concentrations of 95Zr, 95Nb, 103, 106Ru, 131I, 134, 136, 137Cs, 140Ba, 140La, 141,144Ce, and 239Np were measured with a Ge(Li) detector. The transportation time between Chernobyl and the two sampling sites is in good agreement with times calculated from air mass trajectories. The main part of the radioactivity was found on particles with an aerodynamic diameter of less than 2 μm.  相似文献   

8.
Specific features of the horizontal and vertical distribution of uranium and thorium in soils and parent materials of the Southern Urals within the Bashkortostan Republic have been studied with the use of mass spectrometry with inductively coupled plasma. The dependence of distribution patterns of these elements on the local environmental conditions is shown. A scale for soil evaluation according to the concentrations of uranium and thorium (mg/kg) is suggested: the low level, up to 3; medium, up to 9; high, up to 15; and very high, above 15 mg/kg. On the basis of to this scale, the ecological state of the soils is evaluated, and the schematic geochemical map of the region is compiled. The territory of Bashkortostan is subdivided into two parts according to the contents of radioactive elements in soils: the western part with distinct accumulation of uranium and the eastern part with predominant thorium accumulation. This finding supports the charriage (thrust fault) nature of the fault zone of the Southern Urals. The vertical distribution patterns of uranium and thorium in soils of the region are of the same character. The dependence between the contents of these two elements and rare-earth elements has been established. The results of this study are applied for assessing the ecological state of soils in the region.  相似文献   

9.
The analysis of gamma emitters natural radionuclides, i.e., 226Ra, 232Th, and 40K, has been carried out in soil, vegetation, vegetable, and water samples collected from some Northern area of Pakistan, using gamma-ray spectrometry. The ??-ray spectrometry was carried out using high-purity Germanium detector coupled with a computer-based high-resolution multi-channel analyzer. The activity concentrations in soil ranges from 24.7 to 78.5 Bq?kg?1, 21.7 to 75.3 Bq?kg?1, and 298.5 to 570.8 Bq?kg?1 for 226Ra, 232Th, and 40K with the mean value of 42.1, 43.3, 9.5, and 418.3 Bq?kg?1, respectively. In the present analysis, 40K was the major radionuclide present in soil, vegetation, fruit, and vegetable samples. The concentration of 40K in vegetation sample varied from 646.6 to 869.6 Bq?kg?1 on dry weight basis. However, the concentration of 40K in fruit and vegetable samples varied from 34.0 to 123.3 Bq?kg?1 on fresh weight basis. In vegetation samples, along with 40K, 226Ra, and 232Th were also present in small amount. The transfer factors of these radionuclides from soil to vegetation, fruit, and vegetable were also studied. The transfer factors were found in the order: 40K?>?232Th????226Ra. The analysis of water samples showed activity concentrations values for all radionuclides below detection limit. The internal and external hazard indices were measured and found less than the safe limit of unity. The mean value of outdoor and indoor absorbed dose rate in air was found 64.61 and 77.54 nGy?h?1, respectively. The activity concentrations of radionuclides found in all samples during the current investigation were nominal. Therefore, they are not associated with any potential source of health hazard to the general public.  相似文献   

10.
Suspended particulate matter (SPM) and PM2.5 in the urban and suburban atmosphere of the Kanto Plain of Japan, which includes the Tokyo metropolitan area, during the period 22–26 July 2002 were characterized. Samples of SPM and PM2.5 were collected by low-volume samplers at 6-h intervals at Suginami, Saitama, and Kisai. At all the sites, the major components of SPM and PM2.5 were organic carbon (OC), elemental carbon (EC), and sulfate. The ion balance, the size distributions of the ionic species, and the high correlation between SO4 2? and NH4 + indicated that the main chemical form of sulfate was (NH4)2SO4. The OC/EC ratios were larger in the daytime than in the nighttime. The correlation coefficients of OC, OC/EC, and SO4 2? with ozone concentrations at inland sites (Saitama, Kisai) were higher than those at the coastal site (Suginami). Bound water and hydrogen and oxygen atoms associated with OC, the amounts of which were estimated with a mass closure model, contributed substantially to the total particle mass. The chemical characteristics of the particles indicated that two mechanisms led to high concentrations of SPM and PM2.5: (i) an active photochemical process produced high concentrations of OC and sulfate, leading to a high concentration of (NH4)2SO4 in the particles and to production of secondary organic aerosols; (ii) stable meteorological conditions resulted in accumulation of primary particles, mainly emitted from vehicle exhaust, resulting in high concentrations of OC and EC.  相似文献   

11.
In developing countries, aerosol particles damage the health of hundreds of millions of people. Migration from the country side to megacities increases emissions and exposure to particles. Some countries have started to limit emissions based on particulate mass, but this may increase particle number concentrations. In this study we discuss some earlier measurements carried out in the developing world and compare results from one-week measurement campaigns concerning the particle number size distribution and PM10 mass concentrations in New Delhi, India and Beijing, China. Our results show that submicron particle concentrations are high in both places. The average PM10 concentration was 360 μg/m3 in New Delhi and 120 μg/m3 in Beijing. The corresponding total particle number concentrations in the size range 3–800 nm were 63 000 cm?3 and 35 000 cm?3. Number and mass concentrations and their characteristics showed significantly different behaviour between these two locations, which stresses the importance of long-term simultaneous measurements of both quantities in different types of megacities.  相似文献   

12.
The cell-associated adsorption of thorium or uranium from the solution containing each metal only at pH 3.50 using various microorganisms was examined. Among the species tested, high thorium adsorption abilities were exhibited by strains of the gram-positive bacteria Arthrobacter nicotianae IAM12342, Bacillus megaterium IAM1166, B. Subtilis IAM1026, Micrococcus luteus IAM1056, Rhodococcus erythropolis IAM1399, and Streptomyces levoris HUT6156. And high uranium adsorption abilities were found in some gram-positive bacterial strains S. albus HUT6047, S. levoris HUT6156, and A. nicotianae IAM12342. Among these highly efficient thorium and uranium adsorbing microorganisms, S. levoris, which could adsorb the largest amount of uranium from the aqueous solution at pH 3.50, could adsorb about 383 mol thorium and 390 mol uranium per gram dry weight of microbial cells from the solution containing thorium or uranium at pH 3.50. The amount and time course of thorium adsorbed were almost unaffected by co-existing uranium; however, the adsorption of thorium was faster when carried out after the adsorption of uranium. Thorium adsorption also became faster when uranium was added after thorium adsorption. The effect of pH on thorium adsorption was also discussed.  相似文献   

13.
Fluxes,residence times,and sources of some elements to Lake Michigan   总被引:1,自引:0,他引:1  
Fluxes of 28 elements to Lake Michigan are calculated from literature data on sedimentation rates and concentrations in sediments and water. Lake Michigan residence times are roughly 104 lower than oceanic residence times. A mass balance has been formulated for 24 elements, with soil and aerosol as the only sources. These sources provide fourfold excesses of Cu, Hg, Sb, Se, and V, and order of magnitude deficits for Ca, Mg, Na, and Cl, but account (to within 50%) for the observed inputs of Ag, Al, As, Br, Co, Cr, Fe, K, La, Mn, S, Si, Sc, Th, and Zn. Except for Al, Co, La, Si, and Th, deposition from aerosol accounts for at least one-fifth of the total input.  相似文献   

14.
Mining of uranium and molybdenum ore in South-Eastern Siberia (Russia) by the Priargunsky Mining-Chemical Production Company resulted in 100–600 times enrichment of these elements in neighbouring steppe soils. Some attendant pollutants (thorium, arsenic and heavy metals) also occur in soil in high concentrations. The aim of the study is to assess the impact of the uranium production complex on bioaccumulation of uranium and some other elements in soil-dwelling invertebrates, and their accumulation in hypothetic detritial food webs. The element composition was analysed in four coleopteran and one orthopteran species in the vicinity of a rock dump. Concentrations of uranium (0.6–3.5 mg kg−1) and molybdenum (1.4–8.5) in insects sampled at contaminated sites were 2–12 times as high as in the control site. Most susceptible to accumulation of metals were saprophagous tenebrionid beetles. Nevertheless, lower concentrations of toxicants in necrophages than in phytophages suggests that they dissipate in detritial food chain. Industrial activity of PPGHO results in severe burden of surrounding ecosystems by uranium, molybdenum and attendant metals.  相似文献   

15.
We studied the atmospheric aerosol of a farm directly on farm, downwind, and in the background with the aim to characterize the aerosol source of livestock farming physically and chemically. The farm hosted chicken, cattle and pig.The farm was found to be a source of primary and secondary particles. Super-μm particles of various types were emitted from the stables and adjacent facilities related to farming activities. On farm elevated concentrations of ammonia, particulate ammonium and nitrate were observed. The significant emission of condensation nuclei and large, 2 μm-sized particles (droplets) was observed under humid conditions in plumes which most likely originated from open manure pits at least in one case. It is suggested that this aerosol mode consisted of ammonium haze droplets formed by saturation of advected air with ammonia within a few minutes. In one night, a mass uptake of Δm > 5.4 μg m-3 in the super-μm mode was observed along with a loss of Δm = —1.0 μg m-3 in the sub-μm mode based on differential sampling upwind and downwind of the farm. The particulate matter mass median diameter was correspondingly shifted from 1.32 to 3.39 μm. About one third of the mass increase was due to organic carbon. Furthermore, differential sampling showed particulate calcium and nitrate/nitric acid to be emitted from the farm, too. The study encourages to systematically characterize the aerosol emitted from livestock raising in future studies of similar kind.  相似文献   

16.
Ambient concentrations of PM10 were measured every fifteen minutes from November 2002 to October 2003 at Alsasua (Northern Spain) using a laser particle counter. A high volume sampler was also used to collect 24-h integrated PM10 samples at a frequency of three running days per week (i.e. three consecutive PM10 samples followed by five days without sampling) for gravimetric determination of PM10 mass concentrations followed by chemical analysis of its chemical components. The annual mean PM10 concentration obtained using the laser particle counter with gravimetric correction was 22.7 μg m?3 (365 days), while the mean for the gravimetric samples was 29.5 μg m?3 (134 days). A total of 94 integrated PM10 samples were analyzed for 60 chemical species using a combination of inductively coupled plasma spectrometry (ICP) and ion chromatography (IC). The concentrations of the main PM10 components were found to be generally in agreement with the values reported for other Spanish cities. Bilinear Positive Matrix Factorization (PMF2) was used to study the sources of PM10 and its constituents. Six main sources of PM10 were identified (average contribution to total PM10 mass in parentheses): crustal material (35%), secondary sulfate (21%), secondary nitrate (14%), motor vehicles (12%), sea-salt aerosol (12%) and metallurgical industries (3%).  相似文献   

17.
The value of soil water samples used in ecological studies is highly dependent on the quality of the samplers. Tension soil-water samplers are widely used to extract soil solutions, and the samplers are often tested in the laboratory under conditions that differ significantly from field conditions. This study describes a field procedure useful for comparison of two different tension soil-water samplers. Ceramic and PTFE cups are compared. There were no differences in the concentrations sampled by the two different types of sampler for Na+, K+, Ca2+, Al3+, NH4+, H+ and NPOC (non-purgeable organic carbon). Change in the applied vacuum in the range 0 to –0.4 × 105 Pa did not change the concentrations of chemical species in the collected soil water. The ceramic cups collected significantly larger amounts of water due to differences in the hydrostatic characteristics of the two samplers. It was found that the ceramic samplers collected the highest concentrations of Mg2+ in some situations. The results are evaluated and discussed in relation to the possible sources of errors and the temporal and spatial variabilities.  相似文献   

18.

Purpose

Sediment fingerprinting is a relatively recent research technique, capable of determining the origin of suspended sediment. In this study, we investigated sub-basins within a larger watershed we examined previously. The objectives were to determine if there was spatial variation in the origin of the suspended sediments and to test a streamlined fingerprinting approach which would reduce the cost, thereby paving the way for adoption by government agencies.

Materials and methods

Samples were collected from three tributaries, the outlet of the main stem, and at the middle of the main stem. Two methods to collect suspended sediment samples were compared: a mobile continuous-flow centrifuge and automated samplers. A relatively small initial tracer suite consisting of stable isotopes of nitrogen (N) and carbon (C) (15N and 13C), total N (TN), and total C (TC) was tested. Tracer concentrations were obtained through a single mass spectrometry analysis requiring <1 g of sediment.

Results and discussion

Multivariate discriminant analysis showed that three of the four tracers (δ 15N, δ 13C, and TC) from the initial pool were capable of accurate classification of the source samples. A multivariate mixing model showed that banks contributed the majority of sediment throughout all locations sampled and that in tributaries it was an even more dominant source. Despite variations in land use and stream order, the legacy sediments comprising the banks and floodplains were the main factor in impairment for suspended sediment. We found a small but statistically significant difference in δ 15N and δ 13C concentrations collected using automated samplers vs. the mobile centrifuge, but the effect on analysis of sediment source proportions was minimal.

Conclusions

The results of this study indicate that, at least in the study watershed, the majority of sediment in suspension was of streambank origin. A cost-effective tracer suite was identified as well as an attempt to make a streamlined approach to the technique. The streamlined approach cost much less ($7,550 US) than the conventional approach ($46,600 US) and should be suitable for total maximum daily loads analysis by state government agencies in the Southern Piedmont region of the USA.  相似文献   

19.
Abstract

The leaching of phosphorus (P), nitrogen (N), and radionuclides (232Th, 226Ra, 228Ra, and 40K) from Joel sands amended with red mud/gypsum (RMG) at 9 rates (0, 2, 4, 8, 16, 32, 64, 128, and 256 t/ha) was measured using columns. Intense leaching conditions (34 mm/day for 12 days) and a high rate of applied P (320 kg/ha as superphosphate) and N (680 kg/ha as ammonium nitrate) were used to simulate extremes of irrigated vegetable production on the Swan Coastal Plain. Addition of the highest rate of RMG (256 t/ha) reduced leaching of fertiliser P and ammonium‐nitrogen (NH4‐N) by 85% and 50%, respectively, compared with 0 t/ha after 12 days. At 641 RMG/ha P leaching was reduced 50% compared with 0 t/ha. Nitrate‐nitrogen (NO3‐N) leaching was not affected by addition of RMG.

Reduced leaching of NH4‐N was attributed to an increase in cation exchange capacity of the soil with the addition of RMG. Bicarbonate‐extractable P in the soil increased with rate of RMG to >50 μg P/g soil at 256 t/ha. This indicates that soil testing of residual P could be used to reduce P inputs to vegetable crops after soils were amended with RMG. This would further reduce the impact of vegetable production on the water systems of the Swan Coastal Plain and extend the period of effectiveness of RMG amended soils. The increase in 232Th specific activity in Joel sand amended with RMG was well below statutory limits even at the highest rate. Neither 40K nor 226Ra were detectable in RMG amended sands up to 2561 RMG/ha. There was no evidence of leaching of 226Ra or 228Ra at any rate of RMG. These results suggest that the use of RMG amendment on commercial horticultural properties on the Swan Coastal Plain could be feasible.  相似文献   

20.
Over 3 yr of particulate measurements were made at two high elevation sites in the southern Appalachian Mountains of Tennessee and Virginia. Both dichotomous samplers and filter packs were used to obtain day and night, week-long samples for subsequent elemental and ionic analysis. Total No inf3 sup? (HNO3 + No in3 sup? ) and SO inf4 sup2? averaged, respectively, 1.1 and 5.0 µg m?3 at Look Rock, Tennessee and 2.0 and 6.4 µg m?3 at Whitetop Mountain, Virginia. At Whitetop Mountain, the spring and summer seasons had the highest average SO inf4 sup2? concentrations. Seasonally, total N03 varied little. The diurnal variation of elements and SO inf4 sup2? was small. Only total NO inf3 sup? varied substantially with highest values during the day. The fine fraction (particle diameter < 2.5 µm) accounted for about 67% of the total mass. Fine mass and elemental concentrations were generally higher at Look Rock. The elements comprising the principal mass fraction of the coarse samples (2.5 gm < particle diameter < 10 to 15 µm) were of crustal origin (e.g., Al, Si, Ca, Fe) while the element comprising the principal mass fraction of the fine samples (i.e., S) was of manmade origin. Cluster analysis identified two groups of elements at Whitetop Mountain. These groups, in both the coarse and fine fraction, were associate with a soil and an automobile emission component. At Look Rock, only a soil component was obvious.  相似文献   

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