Investigating the minimum detectable activity concentration and contributing factors in airborne gamma-ray spectrometry

In this study,the theory of minimum detectable activity concentration(MDAC)for airborne gamma-ray spectrometry(AGS)was derived,and the relationship between the MDAC and the intrinsic effi-ciency of a scintillation counter,volume,and energy res-olution of scintillation crystals,and flight altitude of an aircraft was investigated.To verify this theory,experi-mental devices based on NaI and CeBr 3 scintillation counters were prepared,and the potassium,uranium,and thorium contents in calibration pads obtained via the stripping ratio method and theory were compared.The MDACs of AGS under different conditions were calculated and analyzed using the proposed theory and the Monte Carlo method.The relative errors found via a comparison of the experimental and theoretical results were less than 4%.The theory of MDAC can guide the work of AGS in probing areas with low radioactivity.

The Activity Concentrations, Radiation Contamination, and Hazards from Wastes and Soil Samples in Nasirabad Industrial Area, Chattogram, Bangladesh

Soils and other solid wastes from industrial areas of Nasirabad, Chattogram are usually dumped or used for land development. Information about the radioactivity level presented on these soil and wastes enables one to assess any possible radiological hazard to humankind by the use of such materials. A total of 37 (31 soils and 6 solid waste) samples near from different types of industries along four kilometre range were collected. The presence and activity concentrations of naturally occurred radioactive materials (NORM) and anthropogenic radionuclides in the samples were estimated using HPGe detector of 40% relative efficiency. The activity concentration of 226Ra, 232Th and 40K were found to be ranging from 8 ± 2 to 131 ± 18.33 with an average of 21 Bq·kg-1, 10 ± 2.69 to 133 ± 15.96 with an average of 40 Bq·kg-1 and 81 ± 22.68 to 930 ± 260.40 with an average of 449 Bq·kg-1 respectively. Besides this, some hazard indices like, the radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), and the activity concentration index (Iy) were calculated to assess the radiation hazard in this region. The averages of calculated hazard indices were within the normal limits, except the activity concentration index, which shows elevated values. The outcomes of this study could serve as important baseline radiological data for future epidemiological studies and environmental monitoring initiatives in the study area.

Natural Radioactivity Levels and Estimation of Radiation Exposure in Environmental Soil Samples from Tulkarem Province-Palestine

The activity concentrations of the natural radionuclides namely 238U, 232Th, 40K and 137Cs are measured for soil samples collected from different locations of Tulkarem district in West Back-Palestine. High-resolution gamma spectrometry (HPGe detector) was used to determine the activity concentration of these radionuclides in 72 surface soil samples taken from areas in and surrounding Tulkarem city. The concentration of 238U varied in the range 9.7 - 83.5 Bq kg–1 with an average value of 34.5 Bq kg–1, 232Th in the range 5.3 - 44.8 Bq kg–1 with an average value of 23.8 Bq kg–1, 40K in the range 10.2 - 404.0 Bq kg–1 with an average value of 120.0 Bq kg–1 and 137Cs in the range 1.0 - 24.5 Bq kg–1 with an average value of 7.8 Bq kg–1. The results have been compared with those of different countries of the world and Palestine. To assess the radiological hazard of the natural radioactivity, the absorbed dose rate (Dr), the radium equivalent activity (Raeq), the effective dose rate (Eeff), the annual effective dose equivalent (AEDE), Excess Lifetime Cancer Risk (ELCR), the radioactivity level index (Iγ), and the external (Hex) and internal (Hin) hazard indices were calculated .It can be concluded that no risk may threat the residents around and center of Tulkarem city except some areas which activity due to fallout 137Cs were high concentration levels. Hence the probability of occurrence of any of the health effects of radiation is low. Hence, measurements have been taken as representing baseline values of these radionuclides in the soil in studying area.

Assessment of Natural Radioactivity in Rivers Sediment and Soil from the Copper Belt Artisanal Mining Region, Democratic Republic of the Congo

The concentrations and distribution of naturally occurring radionuclides (238U, 235U, 234U, 230Th, 226Ra, 210Pb, 232Th, 228Ra, and 40K) were determined by alpha and gamma spectrometry in soil and sediments collected from Luilu and Dilala rivers located in the mining district of Kolwezi (Lualaba Province) of the Democratic Republic of the Congo. The average concentrations of 238U and 226Ra in the analyzed samples were 5 - 10 times higher than the world average values for soil provided by the United Nations Scientific Committee on the Effects of Atomic Radiation. However, the average concentrations of 232Th were found similar to the world average. In both river basins, artisanal mining activities and mineral washing sites displayed the higher concentration values of radionuclides. The mean values of health risk indices calculated for those sites were found significantly higher compared to world average levels. Radiation protection measures seem needed to ensure the radiation safety of local populations. Graphical Abstract

Natural Radioactivity and Excess Lifetime Cancer Risk Associated with Soil in Kargi Area, Marsabit-Kenya

The main aim of investigating activity concentrations together with distribution of radionuclides naturally in soil from Kargi was to evaluate radiological health hazard together with environmental radioactivity. Research shows radionuclides as one source of exposure due to radiation with detrimental effects health wise for populations found in areas considered high background radiation. After collecting 117 soil samples from the area, analysis was done in order to measure their natural radioactivities due to 40K, 232Th and 226Ra radionuclides. Measurements method of gamma spectrometry employing a high purity germanium (HPGe) detector was employed basically to evaluate the radiological hazard of radioactivities. For 40K, 232Th and 226Ra, mean calculated activities were 353.19 ± 110.07, 7.98 ± 3.98 and 7.37 ± 2.60 Bq·kg -1 respectively. Mean values of absorbed and effective dose rates, external and internal hazard indices together with radium equivalent activity were 23.82 ± 6.59 nGy·h -1 and 0.14 ± 0.04 mSv·y -1, 0.12 ± 0.03 and 0.14 ± 0.04 and 45.90 ± 12.65 Bq·kg -1 respectively. Comparing with approved global values, the values were found to be below the given global limits. Evidence of involvement of metasomatic activity of the radioelements or fractionation during weathering is seen as calculations give a higher value Th/U. Excess cancer risk, calculated from the samples showed lower values as compared to global standard values hence minimal chance of getting cancer disease. The area is safe from cancer causing radionuclides.

Determination of Natural Radioactivity of the <i>Hibiscus sabdariffa</i>Linn (Roselle) Used in Côte d’Ivoire (Ivory Coast)

In this work, ten medicinal and nutritional leaves samples of Hibiscus sabdariffa Linn imported from Mali and Burkina Faso in Côte d’Ivoire and sold on the market were collected. The analysis of these plants using High Purity Germanium detector (HPGE) gamma spectrometry showed the activity concentrations of 226Ra, 232Th, and 40K varied respectively in the range of (1.74 - 0.11) × 10−3 Bq/kg, (6.72 - 0.61) × 10−4 Bq/kg and (4.65 - 0.54) × 10−3 Bq/kg1 in the leaves of H. sabdariffa. The Average Annual Committed Effective Dose (AACED) values from leaves this plant varied from 251.492 × 10−6 to 68.133 × 10−6 mSv/y. These values found are below 0.30 mSv/y, the world average value for an individual. These results show that there is no radiological risk in consuming “bissap” leaves.

Study and Simulated the Natural Radioactivity (NORM) U-238, Th-232 and K-40 of Igneous and Sedimentary Rocks of Al-Atawilah (Al-Baha) in Saudi Arabia

In this work, gamma-ray spectroscopy based on semiconductor hyper pure germanium (HPGe) detector was used to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) for thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The mean values of the activity concentrations of U-238 (Ra-226), Th-232, K-40 and Cs-137 in the igneous samples are found as (11.0, 11.50, 1172.71, 1.47) Bq/Kg respectively. In the sedimentary rocks, the mean values of the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) equal to (12.04, 13.18, 1131.36, 1.60) Bq/Kg respectively. The averages of radiological hazards (Raeq, Hex and Iγ) were calculated and found to be within the UNSCEAR permissible limit values (370 Bq/kg for Raeq, and 1 for Hex and Iγ), except for a slight increase of average value of Iγ in the igneous rock samples (1.36). The results indicate that the dose rate values depend on the kind of rocks (high in some igneous rock samples, and most of sedimentary rock samples have low dose rate). The activities of naturalnuclides were predicted and simulated in T time using a written MATLAB R2020a script based on the average activity concentrations and respective half-lives of U-238 and Th-232 series, and K-40, this is to evaluate the future effects of natural radionuclides on the population and estimate the human inputs in the future.

Measurement of Natural Radioactivity in Lagoon Sands Used in Construction in the District of Abidjan, Côte d’Ivoire

Sand is an important natural material for the construction of houses, work buildings and other public spaces. This work, which is one of the first contributions to the environmental quality of construction materials, concerns the measurement of natural radioactivity in the lagoon sands collected in the district of Abidjan. Nineteen (19) samples of these sands are analyzed by gamma-ray spectrometry equipped with HPGe detector. The mean values obtained for 226Ra, 232Th and 40K are respectively 7.76 ± 1.84 Bq·kg-1, 5.21 ± 1.36 Bq·kg-1, and 217.31 ± 5.03 Bq·kg-1. The estimated average value of radium equivalent (Raeq) is 31.94 Bq·kg-1. The results show that the average values obtained are far lower than the global limits of 35, 30, and 400 Bq·kg-1 for the concentrations of 226Ra, 232Th and 40K, respectively, and 370 Bq·kg-1 for the equivalent radium established by the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). Therefore, the use of the analyzed lagoon sand samples in the different construction sectors should not cause serious radiological effects on the populations living in the District of Abidjan. Our results provide new data on building materials radioactivity in Côte d’Ivoire and all over the World. They can also be used as a reference for future work.

In Vitro Anti-Bacterial and Anti-Fungal Activities of Extracts from Different Parts of 7 Zingiberaceae Plants

This study aimed to explore the anti-bacterial and anti-fungal activities of extracts from different parts of plants in the Zingiberaceae family.The inhibitory rate,minimum inhibitory concentration(MIC),and minimum bactericidal concentration(MBC)of leaf and stem,and root and rhizome extracts from Alpinia katsumadai Hayata,Alpinia oxyphylla Miq×Alpinia henryi K.Schumann,Alpinia oblongifolia Hayata,Alpinia nigra(Gaertn.)Burtt,Amomum villosum Lour,Alpinia zerumbet(Pers.)Burtt.et Smith and Alpinia oxyphylla Miq were determined using the fungus cake method and double dilution method.The seven Zingiberaceae plants exhibited characteristic antibacterial activities against pathogenic bacteria and fungi.At a 1.5 mg mL^(−1),A.zerumbet root and rhizome extracts exhibited strong inhibitory activity against S.aureus and E.coli,with 83.23%and 79.62%,respectively.In addition,A.zerumbet leaf and stem extracts had an inhibitory rate of 90.85%against P.aeruginosa.At the same concentration,the leaf and stem,root and rhizome extracts of A.katsumadai had the best anti-bacterial effect against F.oxysporum,with inhibition rates of 84.46%and 84.73%,respectively.Moreover,A.katsumadai and A.zerumbet leaf and stem extracts had the most significant antibacterial effect against S.aureus,with a MIC of 0.063 mg mL^(−1).Thus,both A.katsumadai and A.zerumbet extracts had significant antibacterial activity.In addition,by comparing the inhibitory effect of extracts from different parts,it was found that the inhibitory rate and average inhibitory rate of extracts from leaf and stem were higher than those from root and rhizome.The chemical constituents of A.katsumadai and A.zerumbet,determined by the high-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS),revealed that citric acid(CA),alpinetin,and pinocembrin(PNCB)were the functional constituents yielding the antibacterial activity.Overall,A.katsumadai and A.zerumbet have the potential to be developed as new plant fungicides and bactericides.

改性活性炭富集-火焰原子吸收光谱法测定铜精矿中金

利用改性的活性炭吸附溶液中金,然后采用火焰原子吸收光谱法测定铜精矿中金含量。该方法的线性范围为0～20μg/mL,体系可允许100倍贵金属离子如Pt(Ⅳ),Pd(Ⅱ),Rh(Ⅲ),Ir(Ⅲ)等存在,常见金属离子不干扰测定。用该方法对标准物质进行测定,结果与认定值相符,测定结果的相对标准偏差(RSD)≤3.00%,回收率为88%～98%。

D_(290)树脂-活性炭吸附富集电感耦合等离子体质谱法测定铜精矿中铂钯

矿产品中痕量贵金属元素的测定通常需要富集分离,在检测过程中谱线干扰较多。本文对铜精矿样品在高温下灼烧除去碳和硫,采用盐酸+王水+氢氟酸消解体系进行分解,利用D290阴离子交换树脂-活性炭作为吸附剂富集铂和钯,以Y、In、Bi为内标元素,105Pd和195Pt作为测量同位素,用电感耦合等离子体质谱法(ICP-MS)测定铂和钯的含量。铂和钯的吸附率均达到90%以上,加标回收率分别为92.0%和96.0%,检出限分别为0.126 ng/g和0.105 ng/g,方法精密度(RSD,n=6)小于4%。应用于实际铜精矿样品分析,测定值与锍镍试金-ICP-MS测定结果一致。本法的样品处理体系最大限度地减少了样品中其他金属离子对待测元素的影响,选择的内标元素和高纯氦碰撞反应可有效地减少基体效应和同质异位素干扰。相比于锍镍试金法,该方法的样品前处理简单,铂和钯的富集效果明显,测定检出限低。

提高大气气溶胶放射性分析灵敏度的研究

目的:提高涉核事件监测现场便携式空气采样器监测气溶胶的灵敏度。方法:采用多台便携式空气采样器并联采样,利用无源效率刻度技术对γ能谱进行刻度的测量分析方法。结果:并联采样后单位时间内,采样体积成倍增加,核素的最小可探测活度浓度明显下降。结论:采用多台便携式空气采样器并联的采样和测量分析方法,可显著提高可疑核事件的监测灵敏度。

应用液相色谱-串联质谱测定慈竹笋壳提取物成分及其抑菌活性

通过索式抽提的方法从慈竹笋壳中提取活性物质,并用液相色谱-串联质谱(LC-MS/MS)测定其组成成分。采用K-B抑菌圈法测定慈竹笋壳提取物对4种细菌及2种真菌的抑菌效果,同时测试了笋壳提取物的最小抑菌质量浓度及试验温度、处理时间对其抑菌作用的影响。结果表明:慈竹笋壳提取物包含388种代谢产物,且有20种代谢物的质量超过了整个代谢物总质量的1%。慈竹笋壳提取物能够有效抑制大肠杆菌、肺炎克雷伯菌、粪肠球菌、金黄色葡萄球菌这4类细菌,对桔青霉菌、海绵胶煤炱菌2种真菌无明显抑制作用。其中,肺炎克雷伯氏菌、大肠杆菌的最小抑菌质量浓度为4.375 g·L^(-1),金黄色葡萄球菌、粪肠球菌最小抑菌质量浓度为8.750 g·L^(-1)。抑菌活性具有热稳定性,且随浸泡时间的增加,抑菌活性也会提升。

Characterisation for <i>Radioelements</i>over an Escarpment Feature(S): A Case Study of the Duku-Tarasa Gwandu Ridge Area of Birnin Kebbi NW Nigeria

The paper presents results of radiometric investigations of an area (Duku-Tarasa) near the capital city of the State of Birnin Kebbi, NW Nigeria. The area of study is about 440 m × 420 m and encloses an Escarpment Feature/Structure on a sedimentary rock generally referred to as the Gwandu Formation. The Gwandu Formation (though not described in the paper) consists of continental lacustrine sediments and is the youngest Palaeogene Formation present in the Sokoto sector of the larger Iullemmeden Basin. The study measured, along some selected profiles across this escarpment feature, radiometric signatures using a Sim-Max G411 portable field gamma-ray spectrometer (giving counts for U, Th and K relative to the background values over the area), the ground total-field magnetic data (using the proton precession magnetometer) along those profiles and collected some (5) rock samples for flame photometry and AAS analyses towards the target proposition. Activity concentration levels due to potassium (K), uranium (U) and thorium (Th) were measured in the area along the five established profiles spaced at 50 metres. The results from these measurements and analyses were displayed (in Tables/histograms and gray level maps/images of concentrations of Uranium, Thorium and Potassium prospects) and interpreted (dismissing the magnetic data as seemingly passive as no filter was applied to the mapped data).

典型室内装饰装修材料异味污染物释放和异味活性分析

为研究典型的室内装饰装修材料对室内空气质量的异味贡献程度,采用大体积顶空-三级冷阱预浓缩-气相色谱质谱联用法对典型的7大类室内装饰装修材料异味污染物(内墙涂料、皮革、家具、水性木器漆、胶黏剂、地毯、壁纸)进行定性定量测定.同时对这7大类56种材料的异味活度进行了分析,比较了各类材料的异味释放特点.

活性炭富集—火焰原子吸收光谱法测定金精矿中的金

采用国家标准火试金重量法测定金精矿中的金,存在操作复杂、测试周期长、成本高、污染环境等问题,且不适合批量测定。实验建立了活性炭富集—火焰原子吸收光谱法测定金精矿中金的方法。考察了称样量、焙烧方式、灰化温度、干扰元素和王水用量对金测定的影响。该方法测定范围为10. 00～150. 00 g/t,检出限为0. 019μg/m L,测定结果的相对标准偏差为0. 93%～2. 56%,加入标准物质回收率为96. 5%～103. 1%。本方法与国家标准方法测定结果吻合良好,具有精密度好、准确度高、成本低等优点,适合金精矿中金的批量测定。

4H-SiC中Al离子注入及其二次高温退火技术

在4H-SiC中进行Al离子注入,并进行了二次高温退火技术研究。样品中Al离子的注入浓度为3×10^(19)cm^(-3),对样品进行首次高温退火工艺后,在不同条件下对样品进行二次退火。退火后对样品进行霍尔测试和二次离子质谱(SIMS)测试。测试结果显示,二次退火工艺有助于进一步提升Al离子在碳化硅中的有效电激活率。在1 850℃下进行3 min首次退火后,1#样品的有效空穴浓度只有3.23×10^(17)cm^(-3)。在1 850℃下进行3 min的二次退火后,2#样品的有效空穴浓度增大到了6.4×10^(18)cm^(-3)。同时二次退火导致了Al离子总剂量的降低,二次退火时间越长,温度越高,Al离子总剂量降低越显著。

Radiological Impact Assessment of Mining on Soil, Water and Plant Samples from Okobo Coal Field, Nigeria

Anthropogenic, including mining activities leaves the environment contaminated with potentially toxic substances and remote hazards if not properly checked. The quest in this study is the levels of naturally occurring radionuclides in Okobo coal, Nigeria and their possible distribution in coal mine vicinity soils, water and plants (cassava). Samples were characterized for levels of radionuclides and radiological detriments using high resolution gamma spectrometer, Gamma ray liquid scintillation and applicable radiological hazard indices. The range of mean activity concentrations (Bq·kg-1) for the environmental samples are as follows: 226Ra (8.39 ± 1.0 to 77.6 ± 4.0), 232Th (0.470 ± 0.4 and 77.8 ± 2), and 40K (29.1 ± 0.4 and 289 ± 6), with their respective mean values of 32.7 ± 2.1, 54.0 ± 1.5 and 158.8 ± 3.1 (Bq·kg-1). Radiological detriments including radium equivalent activity (Raeq), external hazard index (Hex), internal hazard index (Hin), radioactivity level index or gamma index (Iγ) and the ELCR for coal sample is 96.94 Bq·kg-1, 0.26, 0.30, 0.69, and 1.56 respectively. Reported values were below the safety limits stipulated by UNSCEAR and implied that the environment is relatively safe with low levels of natural radioactivity. Overall, this background study has demonstrated that Okobo coal mine is a less radio-hazard contributor to environmental samples. Exceptions to this generalization are representative gamma index (Iγr) and annual effective dose equivalent values for some cassava and soil samples, which may call for future impact monitoring.

Radiological Hazard Assessment of Raw Granites from Ranyah, KSA

The assessment of radiological hazard due to external and internal indoor exposure was investigated for 26 raw granites collected from different granite quarries in Ranyah (KSA). The activity concentrations of 226Ra, 232Th and 40K were measured by high-resolution gamma spectrometry. Four granites were classified as “anomalous” due to their relatively high radioactivity. The averages and ranges of their activity concentrations were 667 (305 - 1120), 320 (161 - 491) and 586 (282 - 893) Bq·kg-1, respectively. The corresponding ones for all remaining 22 granites were 45 (18 - 77), 39 (16 - 73) and 1178 (954 - 1531) Bq·kg-1, respectively. In accordance with new European Basic Safety Standards (BSS) directives requiring a uniform reference level for indoor external exposure to gamma rays of 1 mSv·y-1, all 22 granites may be used as bulk or ornamental building materials without any restrictions. Three anomalous granites should be subjected to control to be used as bulk materials. One anomalous granite was categorized as hazardous having an activity concentration index higher than 6. All four anomalous granites exceeded the level of newly adopted reference level of 300 Bq·m-3 for radon indoor exposure in case of poor ventilation. Two of them exceeded even for adequate ventilation. ·

Apply X-Ray Fluorescence and γ-Ray Spectroscopy to Analyze Igneous and Sedimentary Environmental Samples of Al-Atawilah (Al-Baha), Saudi Arabia

Igneous and sedimentary rocks contain an amount of natural radioactivity (NORM). U-238, Th-232 and their decay products, and K-40 are important sources of gamma-radiation. Knowledge of the radionuclide content of rocks is necessary to estimate the exposure of the population to the radiation. Many types of rocks are used in building and industries, thus the radiation detection is important, it provides a baseline map of levels of the radioactivity in the study region. The purpose of this study is to evaluate the activity concentrations of the natural radionuclides (U-238 (Ra-226), Th-232 and K-40) and the fallout nuclide (Cs-137) (if found) in thirty samples of igneous and sedimentary rocks of Al-Atawilah (Al-Baha). The samples were collected and prepared during 2018/2019, and analyzed with a good experimental instrument (High energy resolution γ-ray spectroscopy with HPGe detector), also these rock samples were analyzed with X-ray fluorescence to subdivided these rocks based on the major oxides proportions contained of each sample. The mean activity concentrations of naturally radionuclides were found in the igneous rock samples varied depending on the type of the igneous rock. For sedimentary rock samples, the activity concentrations were found high for quartz sandstone sample, which may be due to its high proportion of SiO2 and K2O. The estimated mean values of absorbed dose rate are within the permissible limit value. The findings indicate high dose level values in granite (rhyolite) and most of diorite (andesite) igneous rock samples while gabbro (basalt) igneous rock samples (except for one sample) record low levels of dose rate. All sedimentary rock samples have low dose rate (except for the quartz sand-stone sample).