Chernobyl radiocaesium in a karst system,Marble Cave,Crimea     

A. B. Klimchouk  V. V. Gudzenko 《Environmental Geology》1996,28(3):161-166

 Surface contamination with radioactive caesium introduced into the environment after the accident at the Chernobyl nuclear plant was high enough in the Crimean Mountains to allow using radiocaesium as an indicator of penetration of radioactive contamination into a karst system. Caesium concentrations have been studied in soils above Marble Cave, Tchatyrdag Plateau, in percolation waters and in sediments transported by percolation waters within the cave. Contamination of the daylight surface with ¹³⁷Cs is about 30 kqB m^–2 which is approximately 13 times higher than the density of global fallouts. Besides ¹³⁷Cs, almost all samples showed presence of ¹³⁴Cs with the ¹³⁷Cs/¹³⁴Cs ratio close to that of Chernobyl contaminations. Concentrations of ¹³⁷Cs range from 9 to 15 mBq l^–1 in the present percolation waters in the cave. In sediments related to percolation waters ¹³⁴Cs is detected in some samples besides ¹³⁷Cs, although the effect of ²²⁸Ac is not ruled out. Surprisingly, the highest concentrations of radiocaesium were measured in "old" sediments in the cave's lower series. These sediments are not associated with modern percolation and are represented by a clay/moonmilk alternating sequence deposited in an old dried cave lake. Moonmilk layers have higher caesium content than clay. It is assumed that Chernobyl caesium was transported into the cave with aerosols which were then deposited mainly in areas where condensation occurs. The sampling site is located just in the boundary between two microclimatic zones with a temperature gradient of 0.5  °C. Active condensation processes occur in this area. Caesium was not detected in another similar sampling site (old lake deposits) located within homogeneous microclimatic conditions. If the above interpretation is correct, these results show the geochemical significance of the aerosol-condensation mechanism of mass transport and localisation. Received: 1 June 1995 · Accepted: 4 December 1995  相似文献   

Plerospheres and their role in reduction of emitted fine fly ash particles     

Fariborz Goodarzi Hamed Sanei 《中国地球化学学报》2006,25(B08):47-48

Particles, less than PM10 in size, emitted from the stack of pulverized coal-fired power plants are of environmental concern since they can easily enter the human respiratory track. These fine particles are examined by Scanning Electron Microscope/Electron Dispersive Spectrometry （SEM/EDX）. Plerospheres are found in fly ash and are particles containing smaller particles formed during combustion of coal. The large plerospheres 〉50 μm mostly are present in ESP fly ash, indicating that they are effectively capturing fine particles and reducing their stack emission.  相似文献   

THE INFLUENCE OF FERTILIZERS, NaHCO3,SOIL TYPE ON CHEMISTRY OF FLOODED SOILS AND RICE PLANT GROWTH     

Ir. Lahuddin M S Zulkifli Nasution 《湿地科学》2006,4(3):161-167

1 INTRODUCTIONQuality of chemical properties of flooded soils isgenerally determined by salinity and alkalinity,bothof these acts as inhibiting factors of plant growth.Thecorrelation of electrical conductivity and other analysisindex has been reported by …  相似文献   

SPATIAL DISTRIBUTION OF NUTRIENTS OF SHALLOW LAKE IN THE ZHALONG WETLAND   总被引：1，自引：1，他引：1  

WANG Lei ZHANG Guang-Xin 《湿地科学》2006,4(3):193-197

1 INTRODUCTIONNitrogen and phosphorus in the water are the nu-trients limited in natural wetlands,which seriously in-fluence on the ecosystem production and the biodiver-sity(Mitsch,Grosselin,2000).Nitrogen and phos-phorus recycles have been interrupted b…  相似文献   

北京地区湿地高等植物区系分析   总被引：2，自引：5，他引：2  

李满良  张铁明  胡东  陈卫 《湿地科学》2006,4(3):219-226

根据工作需要,在北京4个水系的主要河流的平原地段和山区的上、中游地段,选取不同生境的典型样地,以及城区的人工湖泊共设立了35个采集点,采用样方法和样带法相结合,共调查样方355个,采集样本4 152个。在该调查资料的基础上,运用区系学原理对北京地区湿地高等植物区系的种类组成、地理成分(科、属、种3个层次)等进行了系统的分析。结果表明,北京地区湿地高等植物共有108科311属552种(含山区湿地),占北京植物总数的近1/3。其中苔藓植物(B ryohyto)有9科15属18种;蕨类植物(Pteridophgta)5科5属8种;裸子植物(Gymnosperm ae)3科5属6种;被子植物(Angiosperm ae)91科286属520种。种子植物中含20种以上的有5科,共210种;含5种以上的属有14个属,共114种。北京地区湿地植物的分布(即地理成分)较复杂。北京湿地种子植物属的分布区类型有15个类型,9个变型,温带地区类型占主导,温带成分较丰富(属数、种类、比例均占首位)。本区植物区系的主要特征为:①草本植物发达;②温带成分占优势地位;③区系起源古老;④特有属、种匮乏;⑤分布区类型具多样性。  相似文献   

Characterization of microbial communities associated with African desert dust and their implications for human and ecosystem health     

Christina A. Kellogg 《中国地球化学学报》2006,25(B08):218-219

Desert winds aerosolize several billion tons of soil-derived dust each year, including concentrated seasonal pulses from Africa and Asia. Huge dust events create an atmospheric bridge over continents and oceans, and eject a large pulse of soil-associated microorganisms into the atmosphere. These dust events might therefore have a role in expanding the biogeographical range of some microorganisms by facilitating rare long-distance dispersal events. The goal of this study is to characterize the microbes associated with African dust events and determine if they pose a risk to humans or downwind ecosystems. Air samples were collected by vacuum filtration in a source region （Mali, West Africa） during dust events and plated on R2A media to culture microorganisms. These organisms were compared to those in similar samples collected in the Caribbean during Saharan/Sahelian dust events. A high-volume liquid impinger is currently being tested in Barbados, collecting aerosol samples during African dust events. Over 100 bacteria and fungi （19 genera of bacteria and three genera of fungi） have been characterized from source region dust events.  相似文献   

山西霍山植物群落主要层LAI垂直分布规律     

杨志芳刘任涛  毕润成 《山地学报》2006,24(B10):307-312

在山西霍山七里峪林场，采用间接的光学测量方法对沿着海拔分布的植物群落主要层叶面积指数（LAI）进行了测量，从不同的角度对LAI的垂直分布规律进行分析。结果表明：1．海拔不同，LAI表现出很大的差异，海拔1750m左右的LAI值大于较高与较低海拔的；对LAI和海拔之间的关系进行回归，得到LAI分布的拟合方程：y=b0＋b1x＋b2x^2＋b3x^3（R=0．712，P〈0．01）。2．同一海拔样带，阴坡LAI均大于阳坡，但对同种种群来说，阴坡树种平均胸径并不一定均大于阳坡。3．植被类型LAI比较表现为：低山针叶林〈低山灌丛〈落叶阔叶林〈落叶针叶林〈常绿针叶林；而主要群系LAI比较表现为：油松林（0．38）〈落叶松林（0．78）〈山杨林及其混交林（1．09）〈白桦林（2．00）〈辽东栎林及其混交林（3．73）。4．典型群落LAI值变化分析和人工林与天然林以，比较表明，LAI值在一定海拔达到最大值，这对于山西霍山人工林栽培和丰产林培育等具有重要意义。  相似文献   

A preliminary study on interaction of Hg and Se in Sedum alfredii Hance     

《中国地球化学学报》2006,25(B08):127-128

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福建省滨海火电厂地质灾害问题及风险控制探讨   总被引：1，自引：0，他引：1  

郑承忠 《中国地质灾害与防治学报》2005,16(2):47-52

滨海火力发电厂工程主要包括厂区建筑、码头、管道、取排水、填海和贮灰场等工程。其主要面临着福建省海岸带构造运动、断裂及地震活动、港湾淤积、海底滑坡、软土地基、海底活动地貌、基岩不均匀风化以及人类工程活动等主要的灾害性地质因素。通过对这些因素潜在的致灾特点分析，提出了滨海火电厂地质灾害风险控制应包括选址阶段地质灾害风险回避、设计施工阶段地质灾害风险处理及运行阶段地质灾害风险监控等3方面。地质灾害风险评估是滨海火电厂地质灾害风险控制的首要任务。针对滨海电厂工程的特点，评估内容应着重于地质灾害危险性评估及易损性评估。选址阶段地质灾害风险回避主要是对构造不稳定的回避。地质灾害风险处理主要是电厂工程的基础处理及管道抗冲刷处理。电厂运行阶段地质灾害风险监控主要是对建筑物基础稳定性及海域冲淤变化的监控。  相似文献   

蓖麻生长农业气象条件分析及栽培技术初探     

刘海蓉  李凤琴吴明 《沙漠与绿洲气象(新疆气象)》2005,28(1):16-17,23

根据对蓖麻发育期的观测，结合当地气象条件，分析了阿克苏种植蓖麻的适应性及栽培中应采取的趋利避害的技术措施。  相似文献