华东某铀矿区周边河流表层沉积物的天然放射性评价

利用高纯锗γ能谱分析仪测量中国华东某铀矿区附近河流沉积物的放射性核素比活度,计算γ辐射吸收剂量率(D)、有效镭浓度(Ra_(eq))、外照射指数(H_(ex))、内照射指数(H_(in))、年有效剂量当量(AEDE(室内和室外))和年性腺剂量当量(AGDE)等放射性参数,并开展沉积物的放射性危害评估,最后通过Pearson线性系数确定放射性核素比活度之间的相关性。结果表明,河流沉积物中放射性核素~(238)U、~(226)Ra、~(232)Th和40K的平均比活度分别为51.55、37.32、57.63和756.86 Bq·kg~(-1),除~(226)Ra外,其他放射性核素的比活度均高于中国平均值;距离污染区较远或存在河流稀释作用的区域,沉积物的天然放射性核素处于正常水平,作为建筑材料使用时比活度不存在超标;放射性核素~(238)U、~(226)Ra和~(232)Th之间存在显著相关性。     

The influence on the radioxenon background during the temporary suspension of operations of three major medical isotope production facilities in the Northern Hemisphere and during the start-up of another facility in the Southern Hemisphere

Medical isotope production facilities (MIPF) have recently been identified to emit the major part of the environmental radioxenon measured at many globally distributed monitoring sites deployed to strengthen the radionuclide component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT) verification regime. Efforts to raise a global radioxenon emission inventory revealed that the yearly global total emission from MIPF’s is around 15 times higher than the total radioxenon emission from nuclear power plants (NPP's).Given that situation, from mid 2008 until early 2009 two out of the ordinary hemisphere-specific events occured:1) In the Northern hemisphere, a joint temporary suspension of operations of the three largest MIPF's made it possible to quantify the effects of the emissions related to NPP’s. The average activity concentrations of ¹³³Xe measured at a monitoring station close to Freiburg, Germany, went down significantly from 4.5 ± 0.5 mBq/m³ to 1.1 ± 0.1 mBq/m³ and in Stockholm, Sweden, from 2.0 ± 0.4 mBq/m³ to 1.05 ± 0.15 mBq/m³.2) In the Southern hemisphere the only radioxenon-emitting MIPF in Australia started up test production in late November 2008. During eight test runs, up to 6.2 ± 0.2 mBq/m³ of ¹³³Xe was measured at the station in Melbourne, 700 km south-west from the facility, where no radioxenon had been observed before, originating from the isotopic production process.This paper clearly confirms the hypothesis that medical isotope production facility are at present the major emitters of radioxenon to the atmosphere. Suspension of operations of these facilities indicates the scale of their normal contribution to the European radioxenon background, which decreased two to four fold. This also gives a unique opportunity to detect and investigate the influence of other local and long distance sources on the radioxenon background. Finally the opposing effect was studied: the contribution of the start-up of a renewed radiopharmaceutical facility to the build up of a radioxenon background across Australia and the Southern hemisphere.     

The importance of physico-chemical parameters on the speciation of natural radionuclides in riverine ecosystems

External gamma radiation levels were measured in the catchment areas of the Sharavathi River and the dose rates in air were found to be in the range 26.0-61.0 nGy h⁻¹. Soil and sediment samples of the riverine environment were analysed for natural radionuclides such as ²²⁶Ra, ²³²Th and ⁴⁰K using a NaI(Tl) gamma spectrometer. The activity concentration of ²¹⁰Pb and ²¹⁰Po in soil and sediment samples was determined by radiochemical separation techniques. Evaluation of the activity concentration of radionuclides with grain size revealed an increase in the activity of ²²⁶Ra, ²³²Th and ⁴⁰K towards fine grain size. The activity concentrations for all isotopes in all samples were not significantly correlated with pH. However, the activity of ²¹⁰Po and ²¹⁰Pb in sediment showed a moderate positive correlation with organic matter content and a good correlation with clay content of sediment.     

The radioactivity measurements in soils and fertilizers using gamma spectrometry technique

Because of their mineral content, soils are naturally radioactive and one of the sources of radioactivity other than those of natural origin is mainly due to the extensive use of fertilizers. The main aim of this paper is to evaluate the fluxes of natural radionuclides in local production of phosphate fertilizers to determine the content of radioactivity in several commercial fertilizers produced in Algeria and to estimate their radiological impact in a cultivated soil even for the long-term exposure due to their application.For these purposes, virgin and fertilized soils were collected from outlying Setif region in Algeria and from phosphate fertilizers used in this area.Gamma spectrometry was exploited to determine activity concentration due to naturally occurring ²²⁶Ra, ²³²Th and ⁴⁰K in five types of samples (two different sorts of fertilizers, virgin and fertilized soils and well water used for irrigation) taken from Setif’s areas.The results show that these radionuclides were present in an average concentration of 134.7 ± 24.1, 131.8 ± 16.7, 11644 ± 550 Bq/kg for the first fertilizer NPK and 190.3 ± 30, 117.2 ± 10.3, 5312 ± 249 Bq/kg for the second fertilizer (NPKs). For the virgin and the fertilized soils, the corresponding values were respectively 47.01 ± 7.3, 33 ± 7, 329.4 ± 19.7 Bq/kg and 53.2 ± 10.6, 50.0 ± 7, 311.4 ± 18.7 Bq/kg. For well water, the values were 1.93 and 0.12 Bq/kg; however the third value was below the Minimum Detectable Activity (MDA).The radium equivalent activity (Raeq) and the representative level index I_γr for all samples were also calculated. The data were discussed and compared with those given in the literature.     

Development of a new aerosol monitoring system and its application in Fukushima nuclear accident related aerosol radioactivity measurement at the CTBT radionuclide station in Sidney of Canada

A high volume aerosol sampler ("Grey Owl") has been designed and developed at the Radiation Protection Bureau, Health Canada. Its design guidance is based on the need for a low operational cost and reliable sampler to provide daily aerosol monitoring samples that can be used as reference samples for radiological studies. It has been developed to provide a constant air flow rate at low pressure drops (∼3 kPa for a day sampling) with variations of less than ±1% of the full scale flow rate. Its energy consumption is only about 1.5 kW for a filter sampling over 22,000 standard cubic meter of air. It has been demonstrated in this Fukushima nuclear accident related aerosol radioactivity monitoring study at Sidney station, B.C. that the sampler is robust and reliable. The results provided by the new monitoring system have been used to support decision-making in Canada during an emergency response.     

Evaluation of natural radioactivity in soil, sediment and water samples of Niger Delta (Biseni) flood plain lakes, Nigeria

This paper presents the findings of a baseline study undertaken to evaluate the natural radioactivity levels in soil, sediment and water samples in four flood plain lakes of the Niger Delta using a hyper pure germanium (HPGe) detector. The activity profile of radionuclides shows low activity across the study area. The mean activity level of the natural radionuclides ²²⁶Ra, ²³²Th and ⁴⁰K is 20 ± 3, 20 ± 3 and 180 ± 50 Bq kg⁻¹, respectively. These values are well within values reported elsewhere in the country and in other countries with similar environments. The study also examined some radiation hazard indices. The mean values obtained are, 76 ± 14 Bq kg⁻¹, 30 ± 5.5 ηGy h⁻¹, 37 ± 6.8 μSv y⁻¹, 0.17 and 0.23 for Radium Equivalent Activity (Ra_eq), Absorbed Dose Rates (D), Annual Effective Dose Rates (E_ff Dose), External Hazard Index (H_ex) and Internal Hazard Index (H_in) respectively. All the health hazard indices are well below their recommended limits. The soil and sediments from the study area provide no excessive exposures for inhabitants and can be used as construction materials without posing any significant radiological threat to the population. The water is radiologically safe for domestic and industrial use. The paper recommends further studies to estimate internal and external doses from other suspected radiological sources to the population of the Biseni kingdom.     

太湖竺山湾底泥中有害物质含量与环境污染评价

对太湖竺山湾湖泊中重(类)金属、磷、硫元素、有机有毒物质的含量及放射性元素的放射强度进行了检测,通过对比雪堰段与周铁段的相关物质含量,分析了有害物质含量差异的原因,并对其环境污染进行了评价.结果表明:太湖竺山湾底泥中重(类)金属含量总体较低,其中雪堰段比周铁段含量高;有机毒物HCHs、DDTs、PCBs、PAHs由于来源不同,两地相关物质含量不同,但总体上含量较低;湖泊底泥中放射性元素铅、铯的放射性强度低,符合我国开放场址土壤中剩余放射性可接受水平的规定.湖泊底泥中含有较高的磷元素,清淤过程应减轻底泥中磷的释放对水体造成的污染.本结果对太湖底泥沉积物的测量,特别是对放射性元素放射强度的检测,有利于全面了解该湖泊沉积的环境污染现状;评价其污染程度,并为太湖污染治理、清淤底泥的后续利用、风险管理提供科学数据和决策支持.     

Current Contents of 90Sr and 137Cs in the Moss–Lichen Cover of Piedmont and Mountain Landscapes of the Northern Urals

The contents of long-lived artificial radionuclides, ⁹⁰Sr and ¹³⁷Cs, were determined in lichens and mosses of different taxa and in the samples of moss–lichen cover taken from the mountain and lowland plant communities of the Northern Urals. The effects of Chernobyl fallout and the dynamics of radionuclide contents in lichens and mosses were analyzed. The concentration of ¹³⁷Cs in the moss–lichen cover was higher in the mountain ecosystems than in the lowland plant communities.     

云南省环境放射性调查及防治对策

对云南省放射源、射线装置和放射性药品底数情况进行了调查,并提出了放射性污染的防治对策及建议。     

便携式净水器净化放射性污染水的研究

用非放射性元素代替放射性同位素进行静态和动态试验。筛选出了对一、二价阳离子有较好处理效果的D1树脂和对阴离子有较好处理效果的D2树脂。该净水器对两个水源中放射性污染物的净化效果表明 ,对试验水样中污染物的放射性强度均能净化( 2 0L)达到 99%以上 ;即使处理水量达到 35L时 ,其净化率仍能达到 97%以上。