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1.
Natural radioactivity and its gamma dose rate in Mission (Texas) soils   总被引:1,自引:0,他引:1  
The activity concentration of radionuclides in 238U, 232Th, and 40K were determined in Mission (Texas) surface soils through gamma-ray spectrometry measurements using hyper pure germanium detector. Activity concentrations of 238U, 232Th, and 40K were 13–32 Bq kg?1 (mean value: 23 Bq kg?1), 17–47 Bq kg?1 (mean value: 31 Bq kg?1), and 100–460 Bq kg?1 (mean value: 300 Bq kg?1) respectively. The absorbed gamma dose rate in air from these soils were found in the range of 23 to 56 nGy h?1 with an average value of 42 nGy h?1. The contribution to the absorbed gamma dose rate in air was observed as 26 % from 238U, 45 % from 232Th, and 29 % from 40K. The outdoor annual effective dose equivalent varied between 28 and 69 μSv y?1 with the mean value of 52 μSv y?1.The evaluated data were compared with the data from different countries and also with the world mean value.  相似文献   

2.
This paper reports the evaluation of the antioxidant potential of the ethanolic extracts of the leaves (EL), flowers (EF), seed pods (EP) and seeds (ES) from Moringa oleifera Lam. The antioxidant potential was assessed, upon the addition of the extracts to fish oil, by means of the total extractable phenol content (TEP), the DPPH· free radical scavenging efficiency and using pressurized differential scanning calorimetry (P-DSC). The results of TEP and DPPH· showed that the ES extract does not present a potential to be used as an antioxidant additive, and it was thus discarded from the remaining analyses. Thus, the following treatments were prepared: pure fish oil, fish oil with BHT (100 mg kg?1), fish oil with TBHQ (100 mg kg?1) and fish oil with EL, EF and EP—all at the concentration of 100 mg kg?1, in relation to the total extractable phenolics contained in each one of the extracts. The leaf and flower extracts displayed a protecting effect, with an increase in about 20 and 11 % of the OIT values, respectively. However, such protection was smaller than that conferred by the synthetic antioxidants utilized. As for the thermal analysis results, it was noticed that EL presented the highest thermal stability among the extracts.  相似文献   

3.
The activity concentration of primordial radionuclides 226Ra, 232Th, and 40K in soil samples of Thirthahalli taluk were measured systematically by using a low background HPGe detector coupled to 16 K MCA. The measured activity concentration of 226Ra lies between 5.1?±?0.2 and 79.5?±?1.7 Bq kg?1with an average activity of 25.99 Bq kg?1, 232Th ranges from 5.1?±?0.3 to 95.3?±?2.2 Bq kg?1with an average activity of 33.60 Bq kg?1and that of 40K varies from 18.3?±?1.5 to 833.4?±?17.5 Bq kg?1with an average activity of 175.52 Bq kg?1. Higher concentration of these radionuclides were found in the soil samples where the regional geology is granites. The consequential gamma dose and the corresponding radiation hazard was also estimated and is found to be within the permissible limits. The possible radiological impact on the public was also determined and these results are presented in this paper.  相似文献   

4.
The activity concentrations and absorbed gamma dose of primordial radionuclides 238U, 232Th and 40K were determined employing γ-ray spectrometry in 31 soil samples from the land area earmarked for house construction in Perambalur district and 14 rock samples from quarries that supply stones for the entire district. The soil samples registered relatively a higher mean value of 13.2 Bq kg?1 for 238U, 66 Bq kg?1 for 232Th and 340.3 Bq kg?1 for 40K as compared to mean values for rock samples (238U—8.0 Bq kg?1; 232Th—65.1 Bq kg?1; 40K—199.1 Bq kg?1). The mean absorbed gamma dose rate for soil (61.4 nGy h?1) marginally exceeded the prescribed limit of 55 nGy h?1 while, rocks registered the mean absorbed gamma dose rate of 10.4 nGy h?1. The mean radium equivalent activity was distinctly higher in soil (130.6 Bq kg?1) than in rock (20.0 Bq kg?1). However, these values were lower than the limit (370 Bq kg?1) set by OECD for building materials. It is evident from the data that the soil and rocks do not pose any radiological risk for house constructions in Perambalur district.  相似文献   

5.
Tiruchirappalli district is naturally endowed with rich building material resources which are also used in neighboring districts. Hence, measurements of activity concentrations and absorbed dose rate of primordial radionuclides (238U, 232Th and 40K) in the rock samples collected from 14 sedimentary rocks and 9 igneous rocks were carried out employing gamma ray spectrometry. In sedimentary rocks the geometric mean activity concentrations of 238U, 232Th and 40K were found to be 7.4, 29.5 and 233.6 Bq kg?1, respectively. On the other hand in igneous rocks geometric mean activity concentrations of 238U, 232Th and 40K were distinctly higher and found to be 13.1, 105.7 and 888.8 Bq kg?1, respectively. The mean radium equivalent activity (Raeq) recorded in both sedimentary (20.8 Bq kg?1) and igneous rocks (245.4 Bq kg?1) were well within the limit prescribed for dwellings (370 Bq kg?1) except Vilathupatti (689.3 Bq kg?1) and Narthamalai (371.6 Bq kg?1). The mean absorbed dose rate from igneous rock (115 nGy h?1) exceeded the prescribed limit of 55 nGy h?1. The mean indoor annual effective dose from the sedimentary rock (0.056 mSv y?1) and igneous rock (0.580 mSv y?1) did not exceed the prescribed limit (1 mSv y?1) except the igneous rock from Vilathupatti (1.51 mSv y?1). The study concludes that sedimentary and igneous rocks analyzed were radiologically safe when used as building materials except igneous rock from Vilathupatti and Narthamalai.  相似文献   

6.
Study on the residue dynamics of chlorpyrifos and cypermethrin in/on pomegranate (Punica granatum L.) and soil was carried out by conducting supervised field trials as per good agricultural practices. A modified QuEChERS was used to extract the insecticides in pomegranate peel and aril and soil. The limit of quantification (LOQ) of chlorpyrifos and cypermethrin were 0.01 and 0.05 mg kg?1, respectively. Residues of the insecticides remained on the fruit surface and movement to the edible part (aril) was not observed. The residues after treatment on fruit peel were 2.46 and 3.51 mg kg?1 and 2.84 and 4.54 mg kg?1 for chlorpyrifos and cypermethrin, respectively, from recommended and double dose treatments. Chlorpyrifos residues degraded faster compared to cypermethrin. The pre-harvest intervals (PHIs) of chlorpyrifos were 22 and 35 days and those of cypermethrin 50 and 73 days, respectively, at recommended and double dose treatments. In the experimental field soil after the second application chlorpyrifos residues were 0.21 and 0.46 mg kg?1 and cypermethrin residues 0.15 and 0.36 mg kg?1. At harvest, both pesticides showed residues below the LOQ. Based on this study, application of cypermethrin towards harvest may be avoided whereas chlorpyrifos can be applied with 22 days PHI.  相似文献   

7.
The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of 77mSe (t ½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42–146 μg kg?1 compared to 52–63 μg kg?1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg?1. The detection limits for selenium by PC-INAA–CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg?1 depending on the major elements present in the samples, while it was 20 μg kg?1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA–CSS method was 7.0 % at the end of cycle #4 for a sample containing 73.7 μg kg?1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg?1 selenium content.  相似文献   

8.
A study of the biodegradation of imidacloprid in soil was carried out under laboratory conditions. Sandy soil samples were fortified with imidacloprid at 50, 100 and 150 mg kg?1 along with 45 x 107 colony forming units (cfus) of Bacillus aerophilus and the samples were compared with unamended soil. The samples were extracted with acetonitrile, cleaned up by treatment with primary secondary amine sorbent and graphitised carbon black. The residues of imidacloprid and its metabolites were analysed by high performance liquid chromatography. The parent compound, imidacloprid, was found to be more persistent in both the treatments. Among metabolites, the highest values were obtained for urea and olefin while 5-hydroxy, 6-chloronicotinic acid (6-CNA), nitrosimine and nitroguanidine (NTG) were also observed in all the treatments in amended soil. In case of unamended (control) soil, 6-CNA was found to be the most persistent metabolite followed by olefin, urea, 5-hydroxy, nitrosimine and NTG metabolites. Total imidacloprid residues for control soil samples followed first-order kinetics at 50 and 150 mg kg?1 but in case of control imidacloprid fortified at 100 mg kg?1, the total residues of imidacloprid and its metabolites followed pseudo-first-order kinetics. The respective half-life value for 50 mg kg?1 was 25.08 days and 30.10 days for both 100 and 150 mg kg?1. However, total imidacloprid residues followed pseudo-first-order kinetics for its applications at 50, 100 and 150 mg kg?1 in sandy loam soil amended with B. aerophilus. The half-life values for 50, 100 and 150 mg kg?1 were worked out to be 14.33, 15.05 and 18.81 days, respectively. With the use of B. aerophilus, the reduction percentage of initial applied dose imidacloprid in sandy loam soil was found to be higher in all the three doses as compared to that of the control samples.  相似文献   

9.
Concentrations of 238U, 232Th, 226Ra, 40K and 137Cs are measured in collected soil samples from various locations in the Thrace region of Turkey. The activity concentrations range from 12.82 to 101.75 Bq kg?1 d.w. (dry weight) for 238U, from 5.16 to 73.34 Bq kg?1 d.w. for 232Th, from 185.54 to 5399 Bq kg?1 d.w. for 40K and from 11.42 to 90.73 Bq kg?1 d.w. for 226Ra. In addition to naturally occurring radionuclides, 137Cs activity concentration is determined between 3.05 and 46.78 Bq kg?1 d.w. for soil samples. Determination of the radiological hazard is achieved through calculations of the external terrestrial gamma dose rate in air (nGy h?1) and annual effective dose rate (mSv year?1) and the results are compared with the similar works in different countries.  相似文献   

10.
The combination formulation of fluopyram and tebuconazole is used for control of fungal diseases and post-harvest disease management of mango. Dissipation study of the fungicides on mango was carried out after giving applications of fluopyram +tebuconazole at the standard and double doses of 150 + 150 and 300 + 300 g active ingredient hectare?1 (g a.i. ha?1), respectively. Fluopyram residues on mango were 0.8 and 0.9 mg kg?1 and tebuconazole residues, 0.308 and 0.4 mg kg?1 after three and four applications at the standard dose. At double dose treatment the residue levels for fluopyram were 1.266 and 1.453 mg kg?1 and tebuconazole, 0.681 and 0.853 mg kg?1, respectively. Residue dissipation in mango fruits followed first order rate kinetics and the half-life (DT50) were 4.3–5.4 days for fluopyram and 3–3.8 days for tebuconazole. Faster dissipation of the fungicides was observed after the fourth treatment which directly correlated to higher rainfall during that period. The combined residues of fluopyram+tebuconazole reduced to below their maximum residue limits (MRLs) within 36–38 days. Dietary risk assessment on human health indicated that fluopyram and tebuconazole application to mango is unlikely to pose risk to human beings. This study gives valuable information on the judicious use of this combination formulation on mango, especially towards harvest.  相似文献   

11.
Trifloxystrobin and tebuconazole are used for control of Sigatoka leaf spot disease of banana. This study was conducted to evaluate residue persistence of the fungicides in/on banana fruit, other edible parts and soil after spray application of the combination formulation, Nativo 75 WG, at the standard dose, 87.5 + 175 and double dose, 175 + 350 g a.i. ha?1. The fungicides were extracted from banana and soil with acetone, partitioned into dichloromethane and cleaned-up using activated charcoal for trifloxystrobin and primary/secondary amine (PSA) for tebuconazole samples. The limit of quantification of the method was 0.05 mg kg?1 for both fungicides. Initial residues of trifloxystrobin were 0.444 and 0.552 mg kg?1 in/on banana with peel (whole fruit), which reached <0.05 and 0.065 mg kg?1 after 30 days from treatment at the standard and double doses, respectively. Tebuconazole residues were 0.636 and 960 mg kg?1 initially and reduced to 0.066 and 0.101 mg kg?1 after 30 days. Trifloxystrobin and tebuconazole degraded with the half-life of about 11 days. Trifloxystrobin or its metabolite was not detected in the fruit pulp. Tebuconazole being systemic in nature moved to the fruit pulp which was highest on the 3rd day (0.103 and 0.147 mg kg?1) and remained for 15 days. Matured banana fruit, flower, pseudostem and field soil were free from fungicide residues. For consumption of raw banana 43 days pre-harvest interval (PHI) is required after treatment of the combination formulation. Therefore application of the fungicides towards maturity stage of the fruits may be avoided.  相似文献   

12.
Measurement of radionuclides concentration in foodstuffs allows to assess the intake’s assimilated dose. This contributes at least one-eighth of the mean annual effective dose due to natural sources. Among the trace elements in foodstuff, potassium is one of the most important elements. It is a well-known essential element and it occurs all over the earth. Three of the most customary consumed foodstuffs in Mexico since pre-Hispanic time (by all social classes) are the following: bean, chili and corn meal (“tortillas”). They were analyzed by γ-spectrometry in order to determine 40K activity concentration, the derived annual effective dose, and the K mass fraction (%). Results show that the mean activity concentration of 40K, annual effective dose and K mass fraction (%) are as follow: 901 ± 90 Bq kg?1, 37.2 ± 3.7 μSv a?1 and 2.84 ± 0.27 % for chili; 510 ± 10 Bq kg?1, 27.5 ± 0.5 μSv a?1 and 1.60 ± 0.04 % for bean; and, 90 ± 30 Bq kg?1, 58.1 ± 19.4 μSv a?1 and 0.27 ± 0.089 % for corn meal, “masa”. The total effective dose intake from these typical foodstuffs is about 0.122 ± 15.6 mSv a?1in Mexico’s urban zones.  相似文献   

13.
We report on a non-covalent functionalization of graphene foam (GF) synthesized via chemical vapour deposition (CVD). The GF was treated with pyrene carboxylic acid (PCA) which acted as a source of oxygen and/or hydroxyl groups attached to the surface of the graphene foam for its electrochemical performance improvement. The modified graphene surface enabled a high pseudocapacitive effect on the GF. A specific capacitance of 133.3 F g?1, power density ~ 145.3 kW kg?1 and energy density ~ 4.7 W h kg?1 were achieved based on the functionalized foam in 6 M KOH aqueous electrolyte. The results suggest that non-covalent functionalization might be an effective approach to overcome the restacking problem associated with graphene electrodes and also signify the importance of surface functionalities in graphene-based electrode materials.  相似文献   

14.
This study evaluates the antidepressant-like effect and analysed the qualitative and quantitative 74 phenolic standards of ethyl acetate fraction from Tabernaemontana catharinensis leaves. Acute administration of fraction in mice reduced the immobility time in forced swimming and tail suspension tests confirming its antidepressant-like activity. The anti-immobility effect elicited by this fraction was prevented by the pretreatment of mice with PCPA (100 mg kg?1), ketanserin (5 mg kg?1), SCH 23,390 (0.05 mg kg?1) or yohimbine (1 mg kg?1). A sub effective dose of the fraction produced a synergistic effect with fluoxetine (5 mg kg?1). Chromatographic analysis identified 4-hydroxybenzoic and p-coumaric acids in the ethyl acetate fraction from T. catharinensis. Capillary electrophoresis presented 7.34 ± 0.02 mg g?1 of p-coumaric acid concentration in the fraction. Therefore, it is possible that antidepressant-like effect elicited by ethyl acetate fraction from T. catharinensis be dependent on the p-coumaric acid.  相似文献   

15.
In this article, we present results obtained from a radiometric survey that was conducted in the Leepa Valley of Azad Jammu & Kashmir, Pakistan. The purpose of current study is to appraise the radioactivity levels and the associated health hazards due to the terrestrial radionuclide in soil and rock samples. In this regard, 16 soil and 17 rock samples were collected from different locations of the Leepa Valley. After processing the samples, activity concentrations of primordial (232Th, 226Ra and 40K) and anthropogenic (137Cs) radionuclides were determined using a P-type coaxial high purity germanium detector. From the results obtained the mean activity concentrations of radionuclides 226Ra, 232Th and 40K in the soil samples were found to be 31.25 ± 0.46, 44.1 ± 1.07 and 575 ± 8.89 Bq kg?1 respectively. Whilst, in rock samples 226Ra, 232Th and 40K mean activities were found as 28.46 ± 0.45, 48.63 ± 1.12 and 666.7 ± 9.39 Bq kg?1, respectively. The 137Cs concentration level in soil and rock samples is found to be 15.04 ± 0.29 and 5.7 ± 0.16 Bq kg?1, respectively. The average radium equivalent activity (R aeq) was found as 143.16 and 142.93 Bq kg?1 in soil and rock samples, respectively. These findings are less than the recommended safe value of 370 Bq kg?1 as given in OECD report (1979). The values of external (H ex) and internal hazard index (H in) are also less than unity. Mean value of absorbed dose rate was found as 69.78 nGy h?1 for the soil samples, which is in good agreement with the world wide average value (70 nGy h?1). Mean value of absorbed dose rate from rock samples was found as 70.01 nGy h?1. Mean values of the annual effective dose is also lower than the values reported for different other countries of the world.  相似文献   

16.
The total metal concentration and bioaccessible concentration of Cr, Mn, Fe, Cu, Zn, Se in Momordica charantia, Asparagus racemosus, Terminalia arjuna and Syzyzium cumini were measured by instrumental neutron activation analysis and by inductively coupled plasma mass spectrometry analysis (ICP-MS). The bioaccessible concentrations were determined in the gastrointestinal digest obtained after treating dried powdered samples sequentially in gastric and intestinal fluid of porcine origin at physiological conditions. The bioaccessible concentration of Fe was in the range of 58–67 mg kg?1, Mn was 10.2–14.6 mg kg?1, Cu was 3.7–4.8 mg kg?1 and Zn was 10.6–18.4 mg kg?1, were within the safety limits set for vegetable food stuff set by Joint FAO/WHO. The bioaccessibility of Zn, an essential element, was high (40–50 %) in M. charantia and in S. cumini. In addition, the total metal contents and bioaccessible concentration of Ni, Se, Cd and Pb in these samples were measured by ICP-MS. The total Cd content in S. cumini (2.6 ± 0.2 mg kg?1) and its bioaccessible concentration (0.6 mg kg?1) were strikingly high as compared to the other samples. Though total Hg contents were determined by ICP-MS, but their bioaccessible concentrations were below the detection limit (0.036 mg kg?1).  相似文献   

17.
In 2002, an extensive study was performed in forest sites of Izmir. This first study results led on the one hand, to quantify of 137Cs and 40K concentration in mushrooms collected in the Izmir region and to a first evaluation of dose in people due to the ingestion of radionuclide-contaminated mushrooms. The mushroom concentration values varied over a wide range from below detection limit to 401 ± 4 Bq kg?1 (dry wt) for 137Cs. The 40K concentration values obtained for different species of mushrooms ranged from 588 ± 26 Bq kg?1 to 2024 ± 63 Bq kg?1 (dry wt). The annual effective dose values due to mushroom ingestion for 137Cs are lower than the ICRP-2007’s reference level value of 1 mSv for “existing” exposure situation. Inductively coupled plasma-mass spectrometry was used to measure many alkali–alkaline earth elements and heavy metals in mushroom samples. The relationships among the concentrations of 137Cs and the stable elements were presented and the occurrence of metals in mushrooms was evaluated.  相似文献   

18.
Healing mud core samples were collected in the San Diego River (Southwest Cuba), in order to determine the behaviour of the radioactivity levels of 226Ra, 137Cs, 232Th and 40K and to evaluate their possible radiological impact on peloide therapeutic uses. The radionuclide concentration ranges in healing mud profiles on Bq kg?1 dry weight varied as follows: 226Ra = 22–26, 137Cs = 4.6–33.0, 232Th = 18–31 and 40K = 208–433. The calculated average radium equivalent activity (82 Bq kg?1), total absorbed dose rate (40 nGy h?1), external hazard index (0.23), annual gonadal dose equivalent (280 μSv h?1) and annual effective dose equivalent (48.5 μSv y?1) are less than international recommended values. Hence, the levels of radioactivity in healing muds from San Diego River are not an impediment for its use for medical proposes.  相似文献   

19.
QuEChERS and solid phase extraction (SPE) methods were applied for determining four herbicides (metazachlor, oxyfluorfen, quizalofop-p-ethyl, quinmerac) and one insecticide (α(±)-cypermethrin) in runoff water, soil, sunflower and oilseed rape plant matrices. Determination was performed using gas chromatography mass spectrometry (GC-MS), whereas high-pressure liquid chromatography mass spectrometry (HPLC-MS) was used for quinmerac. In all substrates linearity was evaluated using matrix-matched calibration samples at five concentration levels (50–1000 ng L?1 for water, 5–500 μg kg?1 for soil and 2.5–500 μg kg?1 for sunflower or oilseed rape plant). Correlation coefficient was higher than 0.992 for all pesticides in all substrates. Acceptable mean recovery values were obtained for all pesticides in water (65.4–108.8%), soil (70.0–110.0%) and plant (66.1–118.6%), with intra- and inter-day RSD% below 20%. LODs were in the range of 0.250–26.6 ng L?1 for water, 0.10–1.8 μg kg?1 for soil and 0.15–2.0 μg kg?1 for plants. The methods can be efficiently applied for field dissipation studies of the pesticides in energy crop cultivations.  相似文献   

20.
The content of total and inorganic arsenic was determined in 16 dietary supplements based on herbs, other botanicals and algae purchased on the Danish market. The dietary supplements originated from various regions, including Asia, Europe and USA. The contents of total and inorganic arsenic was determined by inductively coupled plasma mass spectrometry (ICP-MS) and anion exchange HPLC-ICP-MS, respectively, were in the range of 0.58 to 5.0 mgkg?1 and 0.03 to 3.2 mg?kg?1, respectively, with a ratio between inorganic arsenic and total arsenic ranging between 5 and 100 %. Consumption of the recommended dose of the individual dietary supplement would lead to an exposure to inorganic arsenic within the range of 0.07 to 13 μg?day?1. Such exposure from dietary supplements would in worst case constitute 62.4 % of the range of benchmark dose lower confidence limit values (BMDL01 at 0.3 to 8 μg kg bw?1 kg?1 day?1) put down by European Food Safety Authority (EFSA) in 2009, for cancers of the lung, skin and bladder, as well as skin lesions. Hence, the results demonstrate that consumption of certain dietary supplements could contribute significantly to the dietary exposure to inorganic arsenic at levels close to the toxicological limits established by EFSA.  相似文献   

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