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.     

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.     

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.     

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.     

Chernobyl radionuclides in a Black Sea sediment trap

The Chernobyl nuclear power station accident released large quantities of vaporized radionuclides, and, to a lesser extent, mechanically released small (less than 1-10 micron) aerosol particles. The total release of radioactivity is estimated to be out of the order of 1-2 x 10(18) Bq (3-5 x 10(7) Ci) not allowing for releases of the xenon and krypton gases. The 137Cs releases of 3.8 x 10(16) Bq from Chernobyl can be compared to 1.3 x 10(18) Bq 137Cs released due to atmospheric nuclear weapons testing. Chernobyl-derived radionuclides can be used as transient tracers to study physical and biogeochemical processes. Initial measurements of fallout Chernobyl radionuclides from a time-series sediment trap at 1,071 m during June-September 1986 in the southern Black Sea are presented. The specific activities of 137Cs, 144Ce and 106Ru in the trap samples (0.5-2, 4-12 and 6-13 Bq g-1) are independent of the particle flux while their relative activities reflect their rates of scavenging in the order Ce greater than Ru greater than Cs.     

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.     

^210Pbex depth distribution in soil and calibration models for assessment of soil erosion rates from ^210Pbex measurements

Throughout the past decade, the potential for using nuclear weapon-produced 137Cs ( half-life 30.2 a) fallout to quantify soil erosion rates on both cultivated and uncul- tivated lands for medium-term timescales (≈ 40 a) has been successfully demonstrated in a wide range of envi- ronments in different regions of the world[1—6]. Because in difficulties of distinguishing Chernobyl-derived compo- nent from total 137Cs input in many parts of Europe, and in measuring low activity samples of…     

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.     

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.     

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.     

基于WRF的“脏弹”恐怖袭击辐射剂量评估方法

提出了一种基于WRF模式的"脏弹"恐怖袭击辐射剂量计算方法。提出了对源项、地表干沉降、湿沉降量的放射性衰变修正方案;并利用该方法计算"脏弹"恐怖袭击造成的辐射剂量。选取某地点作为固定的"脏弹"释放位置,模拟了不同气象条件下的辐射剂量分布。结果表明,以干沉降为主的地表沉降分布,在风场作用下呈条状分布;以湿沉降为主的地表沉降分布,在降水作用下呈块状分布。模拟结果反映了降水对"脏弹"恐怖袭击污染物分布的重要影响。结论表明,模型对降水及沉降过程具有较好的刻画能力,可用于全部放射性污染物质的环境辐射剂量评估。     

Estimation of dry deposition fluxes of major inorganic species by canopy throughfall approach

Dry deposition is an important deposition pathway of pollutants, at least equally important to wet deposi- tion. To understand the total deposition of pollutants, China is lack of the systematic studies on the method- ologies of dry deposition, measuremen…     

云南汛期雨量年代际转折突变的研究

 应用时间序列转折突变点的检测方法,对云南省18个代表站1951～1999年汛期雨量年代际转折突变进行了初步研究.结果表明:云南省18个代表站均存在明显的年代际转折突变.云南大部分地区汛期雨量在50年代发生了多雨转折突变;70年代发生了少雨转折突变;80年代以后云南大部分地区汛期雨量又发生一次多雨转折突变.     

乳牛的乳汁及宫颈粘液流变特性的研究及应用

本文研究了乳牛的乳汁及宫颈粘液的流变特性,得到了这两种体液的宏观流变模型。在跟踪乳牛发情和妊娠期以及考查牛奶成分和健康状况对其流变特性影响的基础上,试图建立两种定量流变学标准分别用于i)判断乳牛的发情和早期妊娠;ii)检验牛奶质量和营养价值以便研制牛奶质量快速测定仪。     

Rapid shifts of the river plume pathway off the Huanghe （Yellow） River mouth in response to water-sediment regulation scheme in 2005

The Huanghe River (Yellow River), historically being considered as the second largest world river in terms of sediment load to the sea (approximately 10.8×108 t/a)[1], has experienced drastic declines in its water and sediment fluxes to the coastal ocean over the past 50 years[2,3]1). A series of consequences of decreasing water and sediment discharge emerged including frequent flow cutoff, lifting of riverbed elevation and lower capability of flood con- trolling. In July 2002 the Yellow Ri…     

一个欧拉型污染物沉降的中尺度模式

本文提出了一个欧拉型的污染物中尺度数值模式,用以研究大气中污染物的输送、转化和干、湿沉降。模式以Anthes等人发展的中尺度气象模式为基础,加入了污染物质量守恒方程组。在方程中包括了源发射率、物质的平流和湍流输送和参数化的气相化学转化和干沉降。作为这一模式的特点是在三维的中尺度模式中嵌入一个一维时变的雨云物理和化学模块,用以研究污染物的湿沉降。用这个模式讨论了湿沉降规律和中国东部地区的污染物浓度和干湿沉降的分布。     

Study and case simulation of a regional dust model coupled with a nonhydrostatic dynamics model

A new regional dust model suitable for simulation and forecasting of dust storms over northern China was described. The dust model was developed by coupling the mesoscale dynamics model MM5 (the Fifth-Generation NCAR/Penn State Mesoscale Model) with a set of mass conservation equations for the particles. The model includes all the atmospheric physical processes of dust storms including occurrence, lifting, transport, and dry and wet deposition. It considers the parameterization of dry and wet deposition, the dust size distribution and microphysical processes in detail. The dust flux from the surface is parameterized based on the friction velocity, which is provided by the mesoscale nonhydrostatic dynamics model, which takes account of the vegetation coverage, land use, soil category, and soil moisture. This new dust model is used to simulate the dust storm that occurred on 19--21 March, 2002 in North China. The results show that there is high dust concentration and its movement is consistent with the surface weather record and satellite monitoring images of the observed dust storm. The simulated dust concentration coincides with the observation data of the particulate concentration of PM10 (dust particles smallerthan 10 μm in diameter). The new numerical model also successfully simulates the formation and migration of the dust storm of 6-8 April, 2002 in North China.     

Desorption characteristics of total phosphorus and heavy metals from impervious urban surface sediments

Dry sediments were collected from one roof and two roads in the central area of Beijing. The sediments were dry and wet sieved. The concentrations of total phosphorus (TP) and heavy metals were analyzed. The highest mass proportion of the dry sediments from the roads were between 125 and 300 μm in diameter, while the roof sediments were much smaller, with 75% of the total sediment mass between 40 and 74 μm in diameter. The concentrations of TP and heavy metals in the roof sediments were much higher than in the road sediments. The concentrations of the six heavy metals investigated had a similar order for all three sampling sites, with the Zn concentration always being the highest, followed by the Mn concentration, and the Ni concentration was always the lowest. After wet sieving, 76.9% to 91% of the TP in the sediments from the three sites remained in undesorbable particulate form, and 68.9% to 97% of the heavy metals were present in undesorbable particulate form. The concentrations of undesorbed heavy metals in the roof sediments tended to increase with increasing sediment size, but a similar trend was not found in the road sediments. This study shows that more attention should be given to the particulate matter in stormwater runoff, as reducing the amount of particulates will improve the efficiency of pollution control measures.     

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。