Chernobyl nuclide record from a North Sea sediment trap

Nuclides liberated by explosion and subsequent fire at Chernobyl No. 4 reactor on 26 April 1986, travelled to Western Europe with lower tropospheric air masses. They reached the northern Alps and Paris on 30 April, southern Great Britain on 2 May, the southern North Sea on 3 May, and the northern North Sea on 3 May and again on 8 May. Levels of deposited activity varied by a factor of 30 or more over distances less than 100 km because of variability of rainfall. A sediment trap deployed 222-m-deep in the North Sea off Bergen recorded the onset and magnitude of the deposition of Chernobyl nuclides. The trap collected 13 samples between 24 April and 21 September 1986. The flux of nuclides adsorbed to particles sinking from surface waters to sediments started less than ten days after contaminated air reached the site. Maximum specific activity occurred on 16-27 May for 137Cs, 134Cs, 106Ru and 103Ru, and on 8-20 June for 144Ce, 95Nb and 95Zr. The highest activity was found for 103Ru. The highest total specific activity of these nuclides in depositing sediments reached 670,000 Bq kg-1, and the highest total activity flux for one day amounted to 50 Bq m-2.     

Impacts of the Fukushima nuclear accident on the China Seas: Evaluation based on anthropogenic radionuclide 137Cs

In order to evaluate the impact of the Fukushima nuclear accident on the China Seas, seawater samples from the South China Sea (SCS), the East China Sea (ECS) and the Yellow Sea (YS) were collected in April–June 2011, and their ¹³⁷Cs activities were measured using low-background γ-spectrometry. ¹³⁷Cs activities in the study area ranged from 0.75±0.07 to 1.43±0.08 Bq m^?3 with an average of 1.12±0.08 Bq m^?3. ¹³⁷Cs activities initially increased from the nearshore to the inner shelf, and subsequently decreased from the inner shelf to the outer shelf. Vertical profiles showed higher ¹³⁷Cs activities at the surface but lower activities at depth in the ECS, suggesting atmospheric input of ¹³⁷Cs. As such, the distribution pattern of ¹³⁷Cs in the region was presumably determined by a combination of atmospheric deposition and subsequent mixing between different water masses including the coastal currents, the Yangtze River plume and the Taiwan Warm Currents. Based on the inventory of 93 Bq m^?2 and the atmospheric deposition flux of ¹³⁷Cs in the ECS of 32.2 mBq m^?2 d^?1 (5.4–42.9 mBq m^?2 d^?1) which we estimated, we derived the residence time of ¹³⁷Cs in the upper water column to be 66 d (45–95 d). We concluded that in terms of ¹³⁷Cs, the ECS was less impacted by the Fukushima accident as compared to the Chernobyl accident. The released amount of ¹³⁷Cs into the ECS from the Fukushima accident was minute.     

Monitoring of atmospheric radionuclides from the Fukushima nuclear accident and assessing their impact on Xi’an, China

Aerosol radionuclides (131I, 134Cs, 137Cs) and gaseous radioactive xenon (133Xe) were monitored at Xi’an, China following the accident at the Fukushima nuclear power plant in March 2011. The additional annual effective dose attributable to the Fukushima emissions was much lower than the public annual effective dose from natural radiation, according to Chinese national standards. The monitoring results were compared with data from other countries as well as with the radionuclide concentrations observed in Xi’an after the Chernobyl nuclear accident in 1986. Possible transport pathways of the released radionuclides from Fukushima to Xi’an were investigated. The occurrence of an anticyclone in the Pacific Ocean region and the extended period over which the radionuclides were released made the determination transport pathways complex, but divergence in the plume and easterly flow evidently brought the initial suite of radionuclides to Xi’an.     

Wet and dry deposition of Chernobyl releases

The passage of the Chernobyl plume over the United Kingdom in May 1986 led to the deposition of radionuclides on the ground by wet and dry deposition processes. Here we analyse rainfall during the passage of the plume and the published monitoring data obtained afterwards, and show that levels of deposited 137Cs can be closely related to rainfall intercepting the plume. 137Cs was present in the atmosphere mostly as particulate species with wet deposition mechanisms dominating. In contrast, 131I was present as particulate and vapour phase material, and reported levels on grass and in cow's milk show that both wet and dry deposition mechanisms were important. 131I on grass and in cow's milk therefore shows a different geographic pattern to 137Cs, and is not so closely related to rainfall. We have calculated washout factors for locations where there are data on deposition, rainfall and air concentrations during the passage of the Chernobyl plume. From these factors and interpolated concentrations in the atmosphere, the total deposition of 137Cs has been estimated at each of 4,000 rain gauge stations in the United Kingdom. The results are presented as deposition contours and have been compared with measurements in parts of the country. Estimates of the total deposition of 131I and 137Cs show that less than or equal to 1% of the estimated total releases from Chernobyl were deposited on the United Kingdom.     

广西北部湾河口及海湾沉积物中137Cs含量分析

【目的】了解广西北部湾河口及海湾沉积物中~(137)Cs的含量,为定量研究北部湾沿岸区域土壤侵蚀和堆积状况,以及评价防城港红沙核电站运行对周围环境的影响提供科学依据。【方法】在广西北部湾河口及海湾中采集32个沉积物样品,利用高纯锗γ谱仪测定样品中~(137)Cs的含量,并与周边的背景值进行比较。【结果】在河口、海湾的表层样中,~(137)Cs比活度较低,范围为0.10~5.94Bq/kg,平均值约为1.23Bq/kg。【结论】表层沉积物中,~(137)Cs含量相对陆地含量要低,主要原因可能是沉积物样品中含沙量大,~(137)Cs吸附量相对较少导致。同时,自然因素和人为活动对~(137)Cs在河口及海湾沉积物中的再分配起重要作用。     

广西乐业天坑群中苔藓的放射性核素分析

为探究广西喀斯特地貌对放射性核素分布及当地环境放射性的影响,利用高纯锗探测器对广西喀斯特地区的大曹天坑和邓家坨天坑采集来的苔藓样品中⁷Be、⁴⁰K、²³⁸U、²³²Th、²²⁶Ra、²¹⁰Pb和¹³⁷Cs的放射性比活度进行测量与分析。结果表明：在苔藓植物中, ⁷Be的放射性比活度为202.3-698.8 Bq/kg [平均值：(430.7±169.7) Bq/kg,n=7];⁴⁰K为33.7-159.9 Bq/kg [平均值：(91.6±44.1) Bq/kg, n=7];²³⁸U为检测限(3.0 Bq/kg)至54.4 Bq/kg [平均值：(16.9±23.6) Bq/kg,n=7];²³²Th为1.2-42.5 Bq/kg [平均值：(14.7±15.9) Bq/kg, n=7];²²⁶Ra为0.7-48.4 Bq/kg [平均值：(16.9±20.3) Bq/kg,n=7];²¹⁰Pb为284.1-950.5 Bq/kg [平均值：(555.5±231.0) Bq/kg, n=7]; ¹³⁷Cs为检测限(0.1 Bq/kg)至2.3 Bq/kg [平均值：(1.1±0.9) Bq/kg,n=7]。对比后发现所有测得的数据均在正常范围内,表明天坑这一喀斯特地貌对放射性核素的分布并没有显著影响,该地区也不存在其他污染来源,同时为我国南方喀斯特地区大气示踪提供数据支撑。     

137 Cs在土壤中淋溶迁移的模拟试验

~(137)Cs作为示踪元素广泛应用于土壤侵蚀及泥沙沉积研究中,其在土壤中的稳定性是决定其能否用于示踪土壤沉积与侵蚀的前提条件.但也有学者对应用~(137)Cs示踪技术的重要假设提出质疑,认为被土壤颗粒吸附的~(137)Cs易解吸成Cs+离子,随水流失或被植物吸收.本文利用双层土柱模拟淋溶装置研究了~(137)Cs和土壤粒径组成在不同雨量条件下的淋失和垂直迁移特征.结果表明,在600~3 000mm降雨量内,土壤中~(137)Cs平均质量活度为10.9Bq·kg-1,略小于试验前的11.5Bq·kg~(-1),与雨量并无显著相关性,土壤中的~(137)Cs有向下垂直迁移现象,但并不显著;土壤中~(137)Cs质量活度与土壤中的黏粒含量有很好的正相关性,决定系数R2达到0.73;有待于增加模拟雨量,作进一步研究.     

Rapid removal of Chernobyl fallout from Mediterranean surface waters by biological activity

The sinking of particulate organic matter from the euphotic zone is an important pathway for the vertical transport of many elements and organic compounds in the sea. Many natural and artificial radionuclides in surface waters are readily adsorbed onto suspended particles and are presumably scavenged and removed to depth on time scales commensurate with both particle sinking rate and retention time of the radionuclide on the particle. Previously, abyssal benthic organisms from the northeast Pacific were found to contain short-lived fission products which entered the sea surface as fallout from nuclear testing. The presence of these radionuclides at great depth could not be explained by Stokesian settling of small fallout particles and it was hypothesized that zooplankton grazing in the surface layers packaged these particle-reactive radionuclides into large, relatively dense faecal pellets which rapidly sank to depth. We report here data from a time-series sediment trap experiment and concomitant zooplankton collections which show conclusively that Chernobyl radioactivity, in particular the rare earth nuclides 141Ce and 144Ce, entering the Mediterranean as a single pulse, was rapidly removed from surface waters and transported to 200 m in a few days primarily by zooplankton grazing.     

~(137)Cs和~(90)Sr-~(90)Y混合源的β放射性强度教学实验研究

当137Cs和90Sr-90Y两个放射源混合时,就会产生混合的β放射性强度。文中寻求一种测量与分析手段来获取两个源混合状态下分别产生的β放射性强度。首先,进行137Cs及90Sr-90Y源混合β放射性能谱测量,再运用费米-居里描绘法对数据进行分析、分解等。在费米-居里描绘上可绘出高、低能区的面积,通过它们各自面积中的粒子数积分就可获得137Cs及90Sr-90Y源分别产生的β放射性强度。137Cs源的强度P=1 346.93 Bq、90Sr-90Y源的强度P=385.47 Bq。     

Preliminary results of the study on wind erosion in the Qinghai-Tibetan Plateau using 137Cs technique

The worldwide fallout of caesium-137 (137Cs) associated with the nuclear weapon tests during the 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. But relatively few researchers have used it to estimate wind erosion. In this note, the 137Cs technique is introduced into the studies of wind erosion and its modern processes in the Qinghai-Tibetan Plateau. Two 137Cs reference inventories of 982.11 and 2 376.04 Bq·m-2 were established preminarily, distributed in the south and middle-north parts of the studied area respectively. By analyzing the patterns of 137Cs depth profiles from sampling sites, the aeolian processes of erosion and deposition in nearly 40 years have been revealed, i.e. the shrub coppice dunes (S1) and semi-fixed dunefields (S3) experienced the alternation of erosion and deposition, while the grasslands (S4, S6 and S7) and dry farmlands (S5) suffered erosion only. By using 137Cs model, the average wind erosion rates for shrub coppice dune (S1), semi-fixed dune fields (S3), dry farmlands (S5) and grasslands (S4, S6 and S7) were estimated to be 84.14, 69.43, 30.68 and 21.84 t·ha-1·a-1 respectively, averaging 47.59 t·ha-1·a-1 for the whole plateau, which can be regarded as of the medium erosion standard. These results derived from 137Cs for the first time have significant implications for the further research of wind erosion and desertification control in the Qinghai-Tibetan Plateau.     

Preliminary results of the study on wind erosion in the Qinghai-Tibetan Plateau using137Cs technique

The worldwide fallout of caesium-137 (¹³⁷Cs) associated with the nuclear weapon tests during the 1950s and 1960s has provided a valuable man-made tracer for studies of soil erosion and sediment delivery. But relatively few researchers have used it to estimate wind erosion. In this note, the¹³⁷Cs technique is introduced into the studies of wind erosion and its modern processes in the Qinghai-Tibetan Plateau. Two¹³⁷Cs reference inventories of 982.11 and 2 376.04 Bq · m⁻² were established preminarily, distributed in the south and middle-north parts of the studied area respectively. By analyzing the patterns of¹³⁷Cs depth profiles from sampling sites, the aeolian processes of erosion and deposition in nearly 40 years have been revealed, i.e. the shrub coppice dunes (S1) and semi-fixed dunefields (S3) experienced the alternation of erosion and deposition, while the grasslands (S4, S6 and S7) and dry farmlands (S5) suffered erosion only. By using¹³⁷Cs model, the average wind erosion rates for shrub coppice dune (S1), semi-fixed dune fields (S3), dry farmlands (S5) and grasslands (S4, S6 and S7) were estimated to be 84.14, 69.43, 30.68 and 21.84 t · ha¹ · a⁻¹ respectively, averaging 47.59 t · ha⁻¹ · a⁻¹ for the whole plateau, which can be regarded as of the medium erosion standard. These results derived from Cs for the first time have significant implications for the further research of wind erosion and desertification control in the Qinghai-Tibetan Plateau.     

137Cs tracing of lacustrine sediments in the Dalian Lake, Qinghai Province, China

Based upon the analysis of Cs and grain-size parameters, the total amounts of ¹³⁷Cs deposition by wind and water in the Dalian Lake of Gonghe Basin, Qinghai Province are defined. The vertical profile of ¹³⁷Cs in the lacustrine sediments exhibits three ¹³⁷Cs activity maxima and one minimum. The major maximum corresponds to the global ¹³⁷Cs fallout in 1963; the two secondary maxima correspond to the leakage of the Chernobyl reactor in 1986 and complete desiccation of the lake in 1994, respectively. The minimum corresponds to aeolian deposition caused by extensive reclamation in the late 1980s and early 1990s. The 137Cs data set was used to evaluate average sedimentation rate of the Dalian Lake since 1963. The deposition was stable in 1963-1986 and 1994-1998, and it was rapid during 1986-1994. This preliminary study reveals that l37Cs has the same potential to trace environmental changes introduce by human interference in arid/semiarid regions as in humid regions.     

稳定区的第二类6×6核素分布区

在氘氚结团核素图中说明了坐标S=2Z-N与加J=S+K常数列确定的13个6×6核素区分布情况.这类核素分布区可组成14个由3个6×6核素区组合成的单位区或16个并列双3区;8个6×6核素区组合成5个亚区,一个亚区是坐标S的2×4区,一个亚区是差K的3+5区,还有3个是3平行线共线组合区,5个亚区中心沿5核素I12753327421,Cs13255337722,La13757348023,Ce14058348224Pr14359348425和分布.核素区的范围是坐标S24～S42,H42～H2与(S+K)=34～54.组合区中心的数值显示出美妙的联系.     

Solidification of Spent Ion Exchange Resin Using ASC Cement

IntroductionSpent ion exchange resins(IERs) comprise themajor fraction of low and intermediate levelradioactive wastes in nuclear facilities,such asnuclear fuel reprocessing plants and nuclear powerstations.This kind of radwaste is difficult to treatand there is no practicable treatment technologycurrently available in China. Solidification of spentIER by cement has been used in several countriesdue to simple operation,low expense andendurance in the disposal environment[1] .However,some de…     

β计数法测定水环境中的131I

131I是核医学应用中非常重要的核素,同时也是核泄漏事故中释放的主要裂变核素之一,其准确测定对于环境保护具有非常重要的意义.本文详细描述了不同水环境中的131I的β计数测定法,并对海水、放射性废水等不同水环境样品进行了检测,结果表明:1)本研究中碘的化学回收率为85.39%～94.47%,平均值为90.90%;2)海水样品平行样中131I的体积比活度为0.673 4～0.735 1 Bq/m3,放射性废水平行样中131I的体积比活度为16.80～17.43 Bq/m3,平行样研究结果表明此方法的重现性很好.     

籽晶保护条件下铈掺杂溴化镧晶体生长及其性能

为定向生长出铈掺杂溴化镧（LaBr3:Ce）晶体,改进了坩埚下降法,并在籽晶接种过程引进冷却气体的保护装置。生长出的LaBr3:Ce晶体在137Cs放射源辐照下,其能量分辨率为3.08%,衰减时间为20.1 ns。采用多通道DRS4采集系统,以XP20D0型光电倍增管耦合 Ф 20 mm×5 mm 溴化镧器件作为开始道探测器,H8500型光电倍增管耦合LaBr3:Ce阵列作为被测停止道探测器,放射源为22Na（511 keV）。制备了6×6的LaBr3:Ce阵列,单根晶体条的尺寸为2 mm×2 mm×15 mm。利用数字化波形分析法,获得阵列的清晰二维散点图和一维位置谱,阵列x和y方向的位置分辨率分别为1.01 mm和0.89 mm。制备出的LaBr3:Ce晶体具有优异的能量分辨率和位置分辨率,可以应用于PET等医学成像技术领域。     

Ru/Mn_xCe_(1-x)O_2催化苯甲醇液相氧化制苯甲醛

采用3种不同方法制备了Mnx Ce1-x O2载体,并通过负载Ru制得2.5%Ru/Ru/Mnx Ce1-x O2催化剂,考察了载体的制备方法、焙烧温度及n(Mn)∶n(Mn+Ce)对催化剂活性的影响.实验结果表明,由溶胶-凝胶法、n(Mn)∶n(Mn+Ce)=0.50、773K下焙烧制备的载体所制得的2.5%Ru/Ru/Mnx Ce1-x O2催化剂的活性最高,在333K下反应1h,苯甲醛产率达67.4%.XRD、N2物理吸附及SEM表征表明,该条件下制备的Mn0.5Ce0.5O2-sol-gel-773K载体具有完整的孔结构,较大的比表面积,且能够形成较多高分散的Ce-Mn-O复合氧化物.     

Characteristics of 137Cs deposition in steppe area

Soil wind erosion in the semiarid steppe area was studied using the 137Cs tracing technique. Comparisons of 137Cs deposition characteristics between different soil profiles indicated that slight aeolian activities occurred on sandy grasslands and semi-fixed dunes with erosion/deposition rates of less than 0.108 cm/a, whereas they were intense on semi-shifting dunes with erosion/deposition rates of higher than 1.35 cm/a.     

放射性核素在包气带中的迁移模拟

为研究核素在包气带中的迁移特征及包气带厚度和泄漏持续时间对核素迁移的影响,通过原位土-水特征曲线测试等获取参数,选用Hydrus-1D模拟不吸附的H-3和吸附的Sr-90在包气带中的迁移。结果表明:包气带对核素迁移存在迟滞作用,Sr-90和H-3到达饱和带时间延长;Sr-90流入饱和带浓度峰值远小于泄漏浓度;小部分(3.8%)H-3和几乎所有Sr-90滞留在包气带;包气带厚度增大,核素到达潜水面时间非线性增大,Sr-90流入饱和带的总量呈数量级递减;泄漏时长增大,流入饱和带的H-3总量呈线性增大、Sr-90总量呈数量级递增。建议如下:不考虑包气带的环评过于保守,建议补充该项工作;应加强监测,一旦发生放射性液体泄漏,应立即采取措施切断补给源来缩短泄漏持续时间,并可采取降低地下水位增大包气带厚度的应急措施降低放射性核素对地下水的污染。     

实验红鲫对137Cs 辐射的氧化应激响应

摘要: 目的探讨实验红鲫对137 Cs 辐射的氧化应激响应和氧化应激生物标记物。方法实验红鲫分别以0 Gy、1. 94 Gy、3. 88 Gy、7. 76 Gy、15. 53 Gy137Cs 辐照,分别于24 h,48 h,72 h,96 h 取出肝脏、性腺,按试剂盒方法检测SOD、GSH-PX 活性,于7 d 和14 d 取出肝脏、肾脏、心脏、脑,按Western blot 方法检测HSP70 含量。结果1. 94 Gy至15. 53 Gy137Cs 辐照能引起实验红鲫氧化应激,SOD、GSH-PX 活性和HSP70 含量发生改变。1. 94 Gy137Cs 辐照诱导实验红鲫肝脏SOD 活性升高, 3. 88 Gy、7. 76 Gy、15. 53 Gy137Cs 辐照诱导实验红鲫肝脏SOD 活性下降,且随辐射剂量升高,其SOD 活性逐渐降低。1. 94 Gy 以上137Cs 辐照诱导实验红鲫性腺SOD 活性下降,并随辐射剂量升高和时间的延长而下降,且下降幅度较大。各辐照处理组实验红鲫肝脏和性腺的GSH-PX 活性变化不大,表现出随辐射剂量升高则活性降低的变化趋势。137Cs 辐照处理后7 d 和14 d,各辐照处理组实验红鲫肝脏、肾脏、心脏和脑的HSP70 表达量均比对照组的高,且随着137Cs 辐照剂量的增加和时间的延长而升高,均存在着一定的“剂量－ 时间－效应”关系。结论实验红鲫性腺对137Cs 辐射的氧化应激响应较敏感,性腺SOD 和肝脏或肾脏的HSP70 可作为氧化应激标志物。