地幔流体的稳定同位素地球化学综述

总结了 2 0年来国内外学者对地幔流体研究的成果和认识。主要包括地幔流体的性质和组成 ;地幔流体中同位素的含量、组成和赋存形式 ;同位素分馏和地幔脱气等作用对地幔组分的影响等。在不同地区和不同构造环境条件的地幔流体中 ,各种组分含量和同位素组成变化可以很大 ,从一个侧面指示地幔组分的不均一性 ,反映了不同地幔物质的形成历程不同或来自不同的地幔源区。此外 ,还讨论了目前存在的几个疑点     

Methane Emission Estimates from Landfills Obtained with Dynamic Plume Measurements

Methane emissions from 3 different landfills inthe Netherlands were estimated using a mobileTuneable Diode Laser system (TDL). The methaneconcentration in the cross section of the plumeis measured downwind of the source on a transectperpendicular to the wind direction. A gaussianplume model was used to simulate theconcentration levels at the transect. Theemission from the source is calculated from themeasured and modelled concentration levels.Calibration of the plume dispersion model isdone using a tracer (N₂O) that is releasedfrom the landfill and measured simultaneouslywith the TDL system. The emission estimates forthe different locations ranged from 3.6 to 16 m³ ha^-1 hr^-1 for the differentsites. The emission levels were compared toemission estimates based on the landfill gasproduction models. This comparison suggestsoxidation rates that are up to 50% in springand negligible in November. At one of the threesites measurements were performed in campaignsin 3 consecutive years. Comparison of theemission levels in the first and second yearshowed a reduction of the methane emission ofabout 50% due to implementation of a gasextraction system. From the second to the thirdyear emissions increased by a factor of 4 due tonew landfilling. Furthermore measurements wereperformed in winter when oxidation efficiencywas reduced. This paper describes themeasurement technique used, and discusses theresults of the experimental sessions that were performed.     

Integration of multi-channel piezometry and electrical tomography to better define chemical heterogeneity in a landfill leachate plume within a sand aquifer

The Hanai-Bruggeman effective medium theory is used to relate bulk electrical conductivity, measured by surface and cross-borehole images, to fluid electrical conductivity, surface conductance, porosity and the geometry factor, in a medium- to fine-grained sand deposit. The change in bulk EC is caused by the presence of a landfill leachate plume. Repeated electrical images over a period of 16 months indicate that various segments of the plume are moving. The chemical constituents of the leachate plume have been determined by sampling from a bundled piezometer located in the electrical image field. Very close agreement is demonstrated between the fluid EC anomaly and the presence of elevated bulk EC indicating that the electrical images can be used to map the plume geometry and to monitor the movement of the plume segments.     

皖南元古宙基底两套绿岩特征及地壳演化

皖南江南隆起区出露的前寒武系变质杂岩研究的新资料，进一步揭示了岩石成因、时代、地球化学组成和地壳演化特征。重新厘定了上溪群为古元古代，由一套安山岩、英安岩、流纹岩及层凝灰岩经变质而成，它构成了江南-雪峰隆起高原科马提绿岩的一部分。地球化学组成具原始地幔特征。其上的新元古代蛇绿岩套，是由10亿年左右的一套橄榄-蛇纹岩、辉橄岩、辉长岩、堇青石斜长闪长岩、辉绿岩、细碧角斑岩、硅质-碧玉岩组成。其地球化学组成为亏损地幔，呈典型的活动大陆边缘的大洋盆生长层。不整合覆于老地层之上。上述两套岩层性质的确定．证明了元古宙上、下两套绿岩是组成华南基底的主要生长层。由地幔柱活动所引起的两次突变事件形成的火山物质组成了扬子地块的中下地壳。因此，地球系统的演化主要是由地球内部的物质交替所推动，它强烈的影响气圈、水圈、生物圈，也推动生物的前进演化。鉴于此，皖南元古宙绿岩的新资料，无疑是十分重要的，对正确认识华南的壳-幔演化有一定的参考价值。     

Tropospheric NO2 vertical column densities retrieved from ground-based MAX-DOAS measurements at Shangdianzi regional atmospheric background station in China

Ground-basedMulti-AXis Differential Optical Absorption Spectroscopy(MAX-DOAS)measurements were performed at Shangdianzi(SDZ)regional atmospheric background station in northern China from March 2009 to February 2011.The tropospheric NO_2vertical column densities(VCDs)were retrieved to investigate the background condition of the Beijing–Tianjin–Hebei developed economic circle in China.The seasonal variation of mean NO_2tropospheric VCDs(VCD_(Trop))at SDZ is apparent,with the maximum(1.3×10~(16)molec/cm~2)in February and the minimum(3.5×10~(15)molec/cm~2)in August,much lower than those observed at the Beijing city center.The average daytime diurnal variations of NO_2VCD_(Trop )are rather consistent for all four seasons,presenting the minimum at noon and the higher values in the morning and evening.The largest and lowest amplitudes of NO_2VCD_(Trop)diurnal variation appear in winter and in summer,respectively.The diurnal pattern at SDZ station is similar to those at other less polluted stations,but distinct from the ones at the urban or polluted stations.Tropospheric NO_2VCDs at SDZ are strongly dependent on the wind,with the higher values being associated with the pollution plumes from Beijing city.Tropospheric NO_2VCDs derived from ground-based MAX-DOAS at SDZ show to be well correlated with corresponding OMI(Ozone Monitoring Instrument)satellite products with a correlation coefficient R=0.88.However,the OMI observations are on average higher than MAX-DOAS NO_2VCDs by a factor of 28%,probably due to the OMI grid cell partly covering the south of SDZ which is influenced more by the pollution plumes from the urban areas.     

大型自然通风冷却塔环境影响的预测分析研究

大多数内陆核电厂将采用大型自然通风冷却塔作为其二次循环冷却方式,本文基于美国核管会推荐的SACTI程序,给出了该模型的基本原理和框架结构,并以江西彭泽核电厂为例,采用该程序预测分析了该核电厂大型自然通风冷却塔所造成的雾羽和太阳辐射损失的影响。并进一步研究了不同环境风速、相对湿度条件下对冷却塔造成的太阳辐射损失的影响。SACTI模型可以根据厂址逐时气象观测数据,较好地计算可见雾羽的长度、抬升高度和太阳辐射损失,其结果可以作为冷却塔环境影响评价的依据。     

核电厂野外示踪试验的三维数值模拟研究

为深入分析国内某拟选滨海核电厂址的大气扩散特征,在现场野外示踪试验的基础上,采用计算流体动力学（CFD）软件Fluidyn-PANACHE,结合三维GIS、结构化贴体网格构建、区域加密等技术方法,创建了可模拟野外示踪试验的精细化大气扩散模拟系统.相比于高斯模式,CFD模式能够更好地模拟示踪剂在不同下风距离处的峰值浓度和烟羽宽度,对近场及复杂下垫面条件下的扩散模拟更贴合实际,且可在稳态模拟的基础上获得连续变化风场中接近实时模拟的仿真效果.模拟结果的偏差统计分析表明,CFD稳态模拟和高斯模拟的统计学评价指标均位于国际公认的可接受范围内,CFD模拟的随机偏差优于高斯模拟.因此,CFD模式可用于辅助和优化其他核电厂址的野外示踪试验工作,提高我国核安全审评的效率和针对性.     

COMPARISON OF THERMAL SCANNING AND IN SITU TECHNIQUES FOR MONITORING THERMAL DISCHARGES1

ABSTRACT: In situ and remote sensing techniques for measuring thermal plumes are compared for data taken at the Point Beach Nuclear Power Plant on Lake Michigan for five separate occasions. The in situ method employed a boat whose position was determined with a microwave ranging system. Temperatures at the surface and at various depths were measured with fast response thermistor probes. The remote sensing technique utilized an infrared scanner in the 8 to 14 micron range. Comparison of the plumes indicates good agreement with respect to plume configurations, areas within isotherms and centerline temperature decays for all except one occasion, a calm day characterized by no waves, low wind and ambient current velocities. Robable reasons for disagreement under such ambient conditions are discussed. The inherent advantages and disadvantages of each method are discussed in light of the results of the five sets of data. This includes both the data collecting and data analyzing procedures. It is concluded that judicious combination of both methods offers a better picture of thermal plumes than can be obtained by either technique alone.     

PRECISE WATER VELOCITY MEASUREMENTS USING PHOTOGRAMMETRIC TECHNIQUES1

ABSTRACT Necessary input parameters for studying mixing zone characteristics of thermal plumes are horizontal surface and subsurface water velocities. Using time lapse aerial photography and analytical photogrammetric techniques, movements of drogues in an effluent plume were traced. From these traces accurate velocity vectors were obtained. Photographic coordinates of drogue images were measured using a glass scale. From the photo coordinates and the results of a ground control survey, an analytical solution was made for positions of drogues in the water at known intervals of time. Drogue positions were mapped for selected exposures thereby providing a visual display of velocity vectors in the study area. A rigorous error analysis was performed to determine the validity of the computed results.     

浮力羽流低风速的多点实时测量

作者发展了一种浮力羽流低风速的多点实时测量技术。测头端部安装耐热玻璃小球,直径0.8mm,球内装有热电偶和加热电阻丝,测头将风速转换为热电偶的电势。每支测头必须经过专用校准热风洞的单支校验。使用巡回检测系统记录多个测头的电位,得到流场各点风速的统计平均值,实现了低风速场的多点实时测量。本测量系统对火灾科学、环境科学和气象学的实验研究和实地观测是很有用的测量技术。