Spatial distribution of electrical conductivity and stable isotopes in groundwater in large catchments: a geostatistical approach in the Quequén Grande River catchment,Argentina

Stable isotopes and electrical conductivity in groundwater were used as natural tracers to adjust the hydrogeological conceptual model in one of the largest catchments within the inter-mountainous Pampa plain, Argentina. Geostatistical tools were used to define the model that best fitted the spatial distribution of each tracer, and information was obtained in areas where there was a lack of data. The conventional isotopic analysis allowed the identification of three groundwater groups with different isotopic fingerprints. One group containing 56?% of the total groundwater samples suggested a well-mixed system and soil infiltration precipitation as the main recharge source to the aquifer. The other two groups included samples with depleted (25.5?%) and enriched (18.5?%) isotopic compositions, respectively. The combination of δ¹⁸O, δ²H and electrical conductivities maps suggested ascending regional flows and water transfer from the Quequén Grande River catchment to the Moro creek. The spatial interpretation of these tracers modified the conceptual hydrogeological model of the Quequén Grande River.     

集成电路器件微波损伤效应实验研究

 主要介绍了微波脉冲参数变化对集成电路器件微波易损性的影响。实验表明：集成电路器件损伤功率阈值随着微波频率的增加而增大，随着脉冲重复频率的增加而减小。随脉冲宽度的变化较为复杂，总体是随着脉冲宽度的增加损伤功率阈值逐渐降低，但存在一拐点区域（约100ns），在此区域后，脉冲宽度增加但器件损伤功率阈值变化不甚明显。器件损伤功率阈值基本呈正态分布，且方差较小，因此，器件的损伤概率近似于0~1分布。     

城市地下水资源可持续开发利用模型研究

根据地下水可持续开发利用原则,运用系统分析方法建立了地下水可持续开发利用模型,首先,运用有限元分析法对地下水运动偏微分方程进行离散,导出了地下水运动的数值方程,使得地下水运动方程能够与系统分析方法相结合建立城市地下水可持续开发利用模型;然后,以地下水位下降最小为目标函数,以各井的出水能力及时段内的需水量作为约束条件,建立了城市地下水优化利用模型,为城市地下水资源可持续开发利用提供新的规划管理方法.     

MODELING OF A BLOCK TARIFF SYSTEM FOR GROUNDWATER REGULATION

The block tariff system is widely used by public utility companies and governments. Because the unit rate is determined at the same time as are choice variables, the resulting endogeneity has been the subject of studies on residential water demand and in labor economics. Without discussing any mechanism that helps people come to their final decisions, these studies rely on observed data and econometric tools to estimate parameters in demand or supply functions. Because their main concern is the amount of resources devoted to a prespecified activity, their methodologies cannot analyze problems in which resources could flow to more than one outlet. This study constructs a computable framework that can deal with the endogeneity issue and help allocate scarce resources to mutually exclusive activities. Using a block tariff system for regulating groundwater extraction by aquaculture farmers in Taiwan as an example, we will show how the government and farmers can rely on the proposed framework to meet their interests.     

小波随机耦合模型在三江平原井灌区地下水位预测中的应用

近些年来,由于水田面积迅速增加,导致三江平原井灌水稻区地下水位普遍下降,"吊泵"、局部超采现象时有发生.为解决上述问题,以853农场为例,对实测地下水埋深资料进行差分处理,采用小波理论和随机水文学方法建立了逐月地下水埋深小波随机耦合模型,精度检验结果表明,模型有效性和可靠性较高.预测结果表明,若仍然采用过去的地下水开采模式,853农场未来地下水埋深将会持续下降,因此当地应加强地下水资源的科学管理.该模型揭示了区域地下水动态变化规律,为853农场乃至整个三江平原地下水资源的可持续利用提供了科学依据.     

Tritium Content and Salinity of Some Groundwaters in Greater Cairo Water Supply Stations

Abstract

Groundwaters from some wells, used for potable water supply from three drinking water stations at Greater Cairo in El-Ameria, El-Harem and Joli Ville, were sampled for tritium measurement. The wells with low tritium content are very suitable for drinking purpose due to the high residence time indicating that the groundwater was away from surface contaminations for a longer time. The pumping of the production wells should be restricted to deep wells of low salinity for drinking purpose. General recommendations are given for the proper approach for exploiting groundwater as a useful and cheap source for drinking water in Greater Cairo.     

Decommissioning of a Nuclear Power Plant: Determination of Site-Specific Sorption Coefficients for Co-60 and Cs-137

Abstract

Assessment of radiological risks in strategies for decommissioning of nuclear installations have to consider not only technical concepts such as cutting and decontamination techniques but, even more important, requirements for input of reliable information on the hydrological situation and retardation capabilities of relevant radionuclides specific to the respective decommissioning operation.

In this paper we describe appropriate methods for obtaining site-specific sorption data and present results achieved from a case study performed as a commercial contractual work preliminary to the planned decommissioning of a nuclear power plant. A detailed mineralogical study of the sediment used in our sorption experiment highlights the necessity of a thorough sample homogenization and characterization. Batch experiments using radiotracer techniques for the determination of site-specific sorption coefficients show significant retardation for Co-60 and Cs-137 after only 2h of equilibration between the preconditioned groundwater and sediment. Sorption is more effective in the groundwater of a deeper aquifer containing a higher amount of colloidal clay (illite) particles < 0.63 μn. The Co-60 radiotracer is more completely sorbed than the Cs-137 radiotracer. Equilibration of radionuclide distribution is slow, particularly for Co-60. Presence of EDTA reduces sorption of Co-60 efficiently while Cs-137 sorption remains unaffected.     

Discussion on the article ＂Chemical influence of groundwater evaluation for geotechnical study＂

现行《岩土工程勘察规范》（GB 50021-2001）对地下水有专门一章内容进行规定,对水样的采取、试验、腐蚀性评价也有原则性规定。《地下水化学影响的岩土工程勘察评价》一文根据3个工程项目的实例,对所取的样品进行了简单的分析,提出用平均值和标准值来进行评估地下水。笔者根据现行规范规定和大量的工程实践认为,该文中许多论点与事实有一定的差距,与岩土工程地质条件、水文地质条件的基础理论有一定的相悖,且在工程实践中操作的可行性也较差。现从实验数据及样本真值、样本数据、分析模型、异常数据处理等方面与该文作者作一探讨。     

Factor Analysis for Assigning Sources of Groundwater Pollution

Abstract

Factor Analysis (FA) is applied to tentatively establish either jhe sources of pollution in the groundwater in a delimited zone in Catalonia which has been polluted by permeation with non-controlled wastewaters or the groundwater evolution with time in this area. Three types of chemical analysis were considered: general parameters indicating the chemical quality of water, inorganic micropollutants and organic micropollutants. These analyses were carried out with forty-five samples collected in three different periods, and eleven parameters were considered. From the final solutions of the FA method applied several factors were retained for the different sampling periods and these factors were related to different sources of pollution. FA has proved to be more useful when punctual pollution incidents takes place rather than when groundwater evolution with time is studied.     

Isotopenhydrogeologische Untersuchungen Im Bacho-Delta (Vietnam)

Abstract

Abecarnil is a β-carboline with high affinity to benzodiazepine receptors. Synthesis and spectral data of the title compound are presented. [¹³C₃]. Abecarnil was synthesized in a five step synthesis. [¹³C₂]Glycine-isopropylester-hydrochloride was condensed with p-methoxy-benzaldehyde to give N-(p-methoxy-benzyliden)-[¹³C₂]glycine-isopropyl-ester. Further reaction with 5-benzyloxy-pseudogramine and the introduction of [¹³C]formaldehyde in a Pictet-Spengler reaction yielded the intermediate 1,2,3,4-tetrahydro-β-carboline derivative. The following dehydration led to [¹³C₃]Abecarnil in an overall yield of 23%