环境水中210Pb和210Po的同时测定

本文叙述了环境水中低水平²¹⁰Pb和²¹⁰Po的分析方法。取水样40L以铅和铋作载体与碳酸钙共沉淀浓集²¹⁰Pb和²¹⁰Po, 在盐酸介质中, ²¹⁰Po自发沉积于银片上, 用低本底计致器测量²¹⁰Po的α活度将分离。²¹⁰Po的沉积液放置三个月以上.再测定²¹⁰Pb新生的。²¹⁰Po的α活度, 从而计算²¹⁰Pb的活度。     

矿工体内210Po和210Pb含量及其与氡子体累积暴露量的关系

调查云南某公司所属矿山矿工肺癌病因时发现,矿工体内²¹⁰Po、²¹⁰Pb含量.明显地高于地面和其他地区人群.本文测定了矿工和对照组尿、头发、肺组织和患肺癌矿工手术时切除的肋骨中²¹⁰Po、²¹⁰Pb含量.发现矿工骨中²¹⁰Pb含量与根据空气氡子体浓度求得的矿工累积暴露量呈幂函数关系.其相关系数为0.75(P<0.001).     

广东高本底地区木薯中天然放射性核素含量及其转移规律的研究

本文对广东高本底地区术薯中天然核素含量分析结果表明。块根中天然U、Th为10^-6g/kg数量级; ²²⁸Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po均为l0^-11Ci/kg数量级。其中²¹⁰Pb含量最高, 达9.30±0.30×10^-11Ci/kg, ²²⁶Ra最底, 为3.09±0.20×10^-11Ci/kg。按我国现行食品卫生标准评价, 块根中天然U, Tb、²²⁶Ra和²¹⁰Po含量低于限制值, 而²¹⁰Pb和²¹⁰Ra含量分别为限制浓度的4.04倍和l0.4倍。自土壤向块根的转移系数, ²¹⁰Pb, ²¹⁰Po为10^-2数量级, 镭同位素为l0^-3数量级, 天然铀、钍为10^-4～l0^-5数量级。     

人体内铅-210和钋-210的浓度

使用低本底α谱仪和²⁰⁹Po放射性示踪剂测定了22例日本人体内胸骨、肝、肾、肺、脾、胆囊、胰腺、性腺和肌肉中²¹⁰Po、²¹⁰Pb的浓度。9种脏器或组织中,胸骨、肝和肾中浓度较高,²¹⁰Po浓度分别为1.29、1.69、1.22Bq·kg^-1湿重;²¹⁰Pb浓度分别为1.27、0.56、0.43Bq·kg^-1湿重。除肝和肾中放射性浓度比明显大于l外,其他组织比值的均值在0.8～1.2之间。根据IcRP参考人数据估算全身负荷量,²¹⁰Po为19.1Bq,²¹⁰Pb为15.8Bq。     

黄河水系中210Pb、210Po的放射性水平

作为黄河水系放射性水平调查的重要组成部分,我们于1993年测定了黄河水系中的²¹⁰Pb和²¹⁰Po,现将结果报道如下。一、材料和方法1样品采集见参考文献[1].2仪器：使用FJ-2603,α、β弱放射性测量装置,仪器本底为110^-4s,²³⁹Pu标准源探测效率为21.5%,探测下限4.0×10^-4Bq.3测量方法：水中²¹⁰Pb、²¹⁰Po的分析方法见参考文献[2]和[3].二、结果黄河水系中²¹⁰Pb和²¹⁰Po的放射性水平见表1.     

226Ra 228Ra 210Pb和210Po在水生生物及食物链中转移规律的探讨

目的 为了解天然放射性核素²²⁶Ra、²²⁸Ra、²¹⁰Pb与²¹⁰Po在水生物及食物链中转移和蓄积情况。方法 定点采集养殖水产品及栖息环境中水与底质沉积物, 按不同的实验需要, 每个鲜样分别剥取肉, 骨(壳),鳞片和胃肠。烹饪样品, 洗净、称重、清炖, 熟后分离出骨(壳),余为食物。样品分别测定²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po含量。数据按统计学要求处理, 配对数据, 作了配对显着性检验。结果 ²²⁶Ra、²²⁸Ra和²¹⁰Pb主要沉积于骨(壳)中, 浓集系数为10²～10³,肉中为10⁰～10².²¹⁰Po主要蓄积在水生物胃肠中, 浓集系数在10²～10⁴,鱼类胃肠与贝类肉中可达10⁴.水产食品烹饪加工过程²²⁶Ra、²²⁸Ra和²¹⁰Pb在食物链中转移不明显, 经配对显着性检验, 差异无显着性(P0.05);然而210Po在淡水鱼类和虾类中转移是明显的, 肉配对检验有非常显着性差别(P<0.01).结论水生物对²²⁶Ra、²²⁸Ra、²¹⁰Pb和²¹⁰Po有很强浓集能力。     

大气中铅-210和钋-210浓度及影响因素

使用²⁰⁰Po示踪α谱法测定了济南,泰安等地大气中²¹⁰Pb和²¹⁰Po的放射性浓度,研究了它们随降雨等影响因素而变化的规律。济南大气中²¹⁰Pb浓度范围为0.20～4.58×10^-8Bq?m^-8,几何平均值为1.35×10^-8Bq?m^-8;²¹⁰Po浓度范围为0.013～2.82×10^-8Bq?m^-8,几何平均值为0.42×10^-8Bq?m^-8,该测值高于现已报道的多数国家和地区。     

山东省食品和水中天然放射性核素水平及所致居民内照射剂量

本文报道了在山东省21个采样点上采集的32种食品和水样中天然铀、钍、²²⁶Pa、²¹⁰Po、²¹⁰Pb和⁴⁰K的含量,并估算了居民年摄入量和所致居民年有效剂量当量。结果表明,在各类食品中均以⁴⁰K活度为最高,²¹⁰Pb和²¹⁰Po次之;居民由食品摄入的放射性核素活度为26.63×10³Bq·a^-1;城乡居民由U、Th、²²⁶Ra、⁴⁰K所致年有效剂量当量基本一致,前者为198μSv,后者为201μSv,全省人口加权平均值为201μSv,与UNSCEAR1982年报道值200μSv相接近。     

广西土壤中放射性核素水平

广西37个土壤样品于1983～1985年采集,以Ge(Li)γ谱仪测定自电镀法测定²³⁸U、²³²Th、²²⁶Ra、⁴⁰K和¹³⁷Cs,自电镀法测定²¹⁰Po和²¹⁰Pb.     

吸烟过程中的210P0的分布及其所致剂量

本文报道了九种过滤嘴香烟的²¹⁰po含量及其在标准吸烟过程中的重新分布。每支香烟的²¹⁰Po平均含量为11.6mBq.在标准吸烟过程中, 香烟中的²¹⁰Po大约有10%转移到主流姻中。由此估算每天吸一包烟的吸烟者, 每年由香烟中吸入的²¹⁰Po是8.8Bq.如果连续吸烟30年, 其累积剂量可达4.5mSv.由此而引起的患致死性肺癌的发病率将为9×10⁶.     

Activity size distributions for long-lived radon decay products in aerosols collected in Barcelona (Spain)

The activity median aerodynamic diameters (AMADs) of long-lived radon decay product (²¹⁰Pb, ²¹⁰Po) in aerosols collected in the Barcelona area (Northeast Spain) during the period from April 2006 to February 2008 are presented. The ²¹⁰Po mean AMAD was 420 nm, while the ²¹⁰Pb mean AMAD was 500 nm. The temporal evolution of ²¹⁰Pb and ²¹⁰Po AMADs shows maxima in autumn and winter and minima in spring and summer. ²¹⁰Pb AMAD are being used to estimate the mean-residence time of atmospheric aerosols.     

Determination of 210Pb and 210Po in water using the extractive scintillation cocktail Polex™

Method validation was performed to achieve the accreditation for our determination method of ²¹⁰Pb and ²¹⁰Po in water. A Pb(NO₃)₂ carrier is added to the sample and lead is precipitated with Na₂SxH₂O. ²¹⁰Po is co-precipitated and the extractive scintillation cocktail Polex^™ is used to determine ²¹⁰Po and ²¹⁰Pb. Uranium is also extracted by Polex^™. It can be removed by washing the precipitate with 1% HNO₃. The ingrowth of ²¹⁰Pb from ²²²Rn during transportation time must be calculated. It has to be subtracted from the original ²¹⁰Pb in the sample and taken into account for the calculation of the lower limit of detection.     

Evaluation of uncertainty and detection limits in Pb and Po measurement in water by alpha spectrometry using Po spontaneous deposition onto a silver disk

An easy and accurate method for the determination of ²¹⁰Pb and ²¹⁰Po in water using ²¹⁰Po spontaneous deposition onto a silver disk is proposed and assessed for its detection capabilities according to the ISO Guide for the expression of uncertainty in measurement (GUM) and ISO Standard 11929-7 concerning the evaluation of the characteristic limits for ionizing radiation measurements. The method makes no assumption on the initial values of the activity concentrations of ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po in the sample to be analyzed, and is based on the alpha spectrometric measurement of ²¹⁰Po in two different aliquots: the first one measured five weeks after the sampling date to ensure radioactive equilibrium between ²¹⁰Pb and ²¹⁰Bi and the second after a sufficient time for the ingrowth of ²¹⁰Po from ²¹⁰Pb to be significant. As shown, for a recommended time interval of seven months between ²¹⁰Po measurements, the applicability of the proposed method is limited to water samples with a ²²⁶Ra to ²¹⁰Pb activity ratio C_Ra/C_Pb≤4, as usual in natural waters. Using sample and background counting times of 24 h and 240 h, respectively, the detection limit of the activity concentration of each radionuclide at the sampling time for a 1 L sample typically varies between 0.7 and 16 mBq L⁻¹ for ²¹⁰Pb in water samples with an initial activity of ²¹⁰Po in the range 0-200 mBq L⁻¹, and between 0.6 and 8.5 mBq L⁻¹ for ²¹⁰Po in water samples with an initial activity of ²¹⁰Pb in the same range.     

Geochronology of lake sediments using 210Pb with double energetic window method by LSC: An application to Lake Van

In this study the age and sediment accumulation rates of the lake sediment were calculated by using the ²¹⁰Pb concentrations through the sediment core. The specific activity of ²¹⁰Pb for each sediment section was determined by LSC with double energetic window method which relies on the direct determination of ²¹⁰Pb without waiting for the in growth of ²¹⁰Po from ²¹⁰Pb. For the successful determination of this radionuclide two counting windows were optimized to eliminate the overlapping of the beta spectra of ²¹⁰Pb and ²¹⁰Bi.     

Calibration of the direct LSC method for radon in drinking water: Interference from 210Pb and its progenies accumulated in 226Ra standard solution

The standard ASTM method is the most commonly applied method for determining ²²²Rn in drinking water. The method is calibrated with a ²²⁶Ra standard solution that usually contains variable amounts of ²¹⁰Pb, ²¹⁰Bi and ²¹⁰Po if the standard has not recently been purified. Until now it has not been experimentally confirmed that these progenies do not interfere when the method is calibrated. In this study, interference was examined using three different organic cocktails and α/β liquid scintillation spectrometry to separately assess the effect of three radionuclides. The interference from ²¹⁰ Po was 4% for one of the cocktails if the ²²⁶Ra standard had been purified 5 years earlier. The interferences from ²¹⁰Pb and ²¹⁰Bi were negligible compared to that of ²¹⁰Po.     

Influence of heavy metals upon the retention and mobilization of polonium‐210 in rats

Purpose: To provide information about the tissue retention and mobilization of the alpha‐emitting radionuclide, polonium‐210 (²¹⁰Po), in rats under combined exposure to heavy metal ions and the chelating agent, 2, 3‐dimercaptopropane‐1‐sulfonate (DMPS).

Materials and methods: Rats were pre‐exposed intraperitoneally to either CdCl₂ or Pb(CH₃COO)₂. 9 or 15?h later they received ²¹⁰Po nitrate intravenously. The retention and excretion of ²¹⁰Po via the urine and faeces of pre‐exposed rats, as well as in pre‐exposed rats treated with DMPS, were followed. The radioactivity due to ²¹⁰Po in a broad spectrum of body tissues and excreta was measured by the liquid scintillation counting after sample digestion in a mixture of perchloric acid and hydrogen peroxide. The immunohistochemical localization of metallothioneins (MT) was studied using a mixture of murine monoclonal antibodies directed against MT I+II.

Results: The present study revealed different tissue distributions of polonium‐210 in the rats pre‐exposed to lead or cadmium ions when compared with that in ²¹⁰Po only controls. Under combined exposure to Pb or Cd, the spontaneous excretion of ²¹⁰Po was enhanced and could be further enhanced by treatment with DMPS. Treatment with this chelator was efficient even when its start was postponed until 24h after internal contamination of the body with ²¹⁰Po.

Conclusions: Polonium‐210 is bound in vivo to binding sites on various biomolecules, among them erythrocytic enzymes and MT. This phenomenon explains the different affinity and overall distribution of ²¹⁰Po in control body tissues. When the appropriate binding sites are occupied by lead or cadmium, enhanced natural excretion of polonium‐210 occurs.     

Morphological features of the microdistribution of naturally occurring 210Pb/210Po and 226Ra in the teeth of children and juveniles

Purpose: To examine the microdistribution of natural α‐radioactivity in deciduous teeth of children and the permanent teeth of juveniles extracted for orthodontic purpose from across the UK.

Materials and methods: The microdistribution of ²¹⁰Pb‐supported ²¹⁰Po and ²²⁶Ra in 708 deciduous and permanent teeth and 32 foetal teeth was measured on 1442 TASTRAK α‐particle track detectors.

Results: Of the various findings, a number are of special interest. Around half of the ²¹⁰Pb activity in the outer enamel of deciduous teeth appears to have been acquired in utero as a result of transplacental transfer. In deciduous and permanent teeth, ²²⁶Ra is concentrated mainly in the circumpulpal region, while the highest levels of ²¹⁰Po are on the highly calcified outer enamel surface. Furthermore, activity concentrations recorded on this surface were ln‐normally distributed.

Conclusions: ²¹⁰Pb‐supported ²¹⁰Po activity on the outer enamel surface of permanent teeth constitutes an assay of cumulative environmental exposure with which to assess exposure in bone, both in utero and in childhood. Such assessment can be used to study geographical variations in the α‐activity in teeth. More work is also required to determine the concentrations of both ²¹⁰Po and ²¹⁰Pb in the foetal skeleton.     

Aspects of the geographical variations of naturally occurring 210Pb/210Po in permanent teeth of juveniles in the UK

Purpose: To study geographical variations in the level of naturally occurring ²¹⁰Pb‐supported ²¹⁰Po in permanent teeth of juveniles in the UK.

Materials and methods: Permanent teeth extracted from 278 juveniles for orthodontic purposes were obtained from 48 counties in the UK. ²¹⁰Po activity concentration was measured on the outer enamel surface using TASTRAK α‐particle‐sensitive plastic track detectors.

Results: Geometric mean±SE activity concentrations in teeth from urban, suburban and rural areas, excluding the high radon area of Devon, were 8.41 +0.25/?0.24, 7.76 +0.37/?0.35 and 7.20 +0.49/?0.46?Bq?kg^?1, respectively. Overall, there was no significant association between α‐activity on the outer enamel surface of permanent teeth and proximity to the major UK motorways. However, when the data were considered with respect to the prevailing south‐westerly wind on the western side of the UK, a statistically significant association with respect to donors living downwind (on the easterly side) of the motorways was found. This effect was greater for sections of the M5 and M6 motorways that traverse urban areas. ²¹⁰Po levels in teeth were also associated with domestic radon concentration. This effect was comparable with that from traffic and urban pollution.

Conclusions: Higher levels of ²¹⁰Pb‐supported ²¹⁰Po are seen in permanent teeth of juveniles near sources of increased exposure in the UK. Inhalation uptake is an important pathway of exposure, especially with respect to domestic radon exposure. The results might be important in assessing integrated exposure to ²¹⁰Po in the skeleton and consequent high linear energy transfer dose to bone marrow.     

Enrichment and vertical profiles of 210Po and 210Pb in monazite areas of coastal Karnataka

A study on radiation level and radionuclide distribution in the environment of coastal Karnataka has revealed the presence of low-level monazite deposit in the Ullal beach area. The paper presents systematic studies on the distribution, enrichment and vertical profiles of ²¹⁰Po and ²¹⁰Pb, important daughter products of ²³⁸U, in Ombattu Kere, Summer Sand and the Bhagavathi Temple region of the Ullal beach area of coastal Karnataka. Sand samples collected at different depths from these locations were analyzed for ²¹⁰Po and ²¹⁰Pb activities to understand the distribution, enrichment and vertical profiles of these radionuclides in monazite area. The activity of ²¹⁰Po in the Ullal region is found to vary from 1.7 to 43.2 Bq kg^?1 with a mean value of 11.2 Bq kg^?1 and that of ²¹⁰Pb varies from 1.0 to 66.7 Bq kg^?1 with a mean value of 19.1 Bq kg^?1. The mean ²¹⁰Po/²¹⁰Pb ratio was observed to be 0.6. The absorbed gamma dose rate in the region varies in the range 39–460 nGy h^?1 with a mean value of 193 nGy h^?1.