GEOCHEMICAL INTERPRETATIONS OF GROUNDWATER FLOW SYSTEMS1

ABSTRACT. Interest in the geochemistry of groundwater is increasing owing to the great number of current projects involving underground liquid waste storage, artificial recharge of potable water, accidental contamination of groundwater bodies, sanitary landfills, and pollution monitoring. Geochemical techniques used to facilitate the understanding of a groundwater system range from extremely simple to those requiring sophisticated theories, equipment, and procedures. An interpretation of the simple trilinear diagram for samples collected from the Yucatan Peninsula of Mexico provided evidence that the fresh-water body was only a few tens of meters thick and was underlain everywhere by an extensive body of salt water. A geochemical technique that has been used effectively to identify the source of salt water in coastal aquifers is measurement of the carbon-14 concentrations. Carbon-14 has been used in a regional carbonate aquifer to determine the velocity of groundwater movement, rates of chemical reactions, and distribution of hydraulic conductivity. The application of principles of irreversible thermodynamics to groundwater systems provides a basis for constructing models which permit prediction, over both time and space, of changes in head distribution and chemical character of the water resulting from imposed stresses on the system. In essence, proper application of irreversible thermodynamics combines the potential theory of Hubbert with principles of reversible chemical thermodynamics, such as solution of carbonate minerals, to describe and explain controlling chemical reactions and processes of groundwater systems.     

Risk analysis for road and rail transport of hazardous materials: a simplified approach

A simplified approach to transportation risk analysis for road and rail transport of dangerous goods is proposed, which is based on the use of a product databank, containing the impact areas for a number of pre-selected accidental scenarios, and on the selection of a few typical average values of the involved parameters, relevant to the type of transport activity and to the route. Such an approach enables also a non-specialist to very rapidly perform a transportation risk analysis, obtaining both individual and societal risk measures for the study case(s): the results may be used to support a decision making process, and/or as a basis for a more in deep analysis.     

A survey on occupational accidents’ reporting and registration systems in the European Union

This paper presents the results of a survey on the procedures for reporting occupational accidents in the EU countries. It focuses particularly on the reporting and registration systems, as well as on the main characteristics of National Databases being used for the production of official statistics. The survey shows that many European countries have different methods and procedures for collecting and compiling data on occupational accidents, which inevitably pose problems when comparing accident statistics between the EU member states.The paper includes a brief review of the main goals and achievements of the European Project ESAW (European Statistics on Accidents at Work), which was launched in 1990 by the Eurostat (European Statistics), for the harmonisation of occupational accidents’ statistics among the member states. It is believed that the new variables being introduced by the harmonised methodology will quickly affect the way in which managers and insurance companies carry out their current procedures in several EU member states.The International Labour Organisation (ILO) recommendations and the future trends are also analysed. In conclusion, the study identifies opportunities for further development and research in the reporting and registration systems of occupational accidents.     

Sydney tar ponds: some problems in quantifying toxic waste

Information on the type and amount of hazardous and toxic waste is required to develop a meaningful strategy and estimate a realistic cost for clean up of the Sydney Tar Pond site which is located on Cape Breton, in the province of Nova Scotia, Canada. The site covers the area of the decommissioned Sysco (Sydney Steel Corporation) plant. The materials of concern include BTEX (benzene, toluene, ethylbenzene, and xylenes), PAH (polycyclic aromatic hydrocarbons), PCB (polychlorinated biphenyl), and particulates laden with toxic metals, such as arsenic, lead, and others. The originally nontoxic materials such as soil, blast furnace slag, and vegetation, as well as surface and ground waters, which were subsequently contaminated, must also be included if they fail tests prescribed by environmental regulations. An extensive sampling program must be undertaken to obtain data for an accurate estimate of the waste to be cleaned and disposed of. Apparently, 700,000 tons of toxic waste, which is believed to be present on the site, may represent only a fraction of the actual amount. The clean-up of the site is only part of the solution. Toxic waste has to be disposed of in accordance with environmental regulations.     

分光光度法测定测田废水中的COD_(Cr)

为了快速监测油田废水中的化学需氧量ＣＯＤＣｒ,因此采用ＴＬ－１（Ａ）型污水ＣＯＤＣｒ速测仪进行加热催化消解,然后再用分光光度比色法测定ＣＯＤＣｒ,实验中进行了方法的准确度、精确度及Ｃｌ－影响实验,并与标准的重铬酸钾法进行了对比实验,结果说明分光光度法简单快速、重现性较好、准确度较高,对同一产品的测定结果与重铬酸钾法非常一致。因此,本方法可用于油田废水中的ＣＯＤＣｒ监测。     

废聚苯乙烯的化学回收方法

废聚乙烯（ＰＳ）转化为燃料油和化学品的化学回收方法,分为废ＰＳ单独裂解及废ＰＳ与其它废塑料混合裂解两种方式,分别阐述了两种回收方式的研究成果和工艺现状,并就存在的问题进行了讨论。     

化学混凝-催化氧化法处理钻井污水

由于钻井污水经混凝处理后仍存在ＣＯＤ、色度超标问题,因此需采用其他方法深度处理污水。故采用混凝－催化氧化法工艺处理钻井污水,混凝剂为硫酸铁或聚合硫酸铁,混凝剂加量一般为２０００ｍｇ／Ｌ,初始ｐＨ值为３．０～５．０,氧化时间为３ｈ等。通过实验结果可知：该方法完全能满足钻井污水处理的要求,处理后出水可达标外排。化学混凝－催化氧化处理工艺是解决高浓度钻井污水处理ＣＯＤ、色度超标的重要途径,在技术经济上是可行的,具有广阔的应用前景     

SYL-01破乳剂的合成及性能测试

在国内外研究的基础上通过实验以MAA、AA、BuAc、MMAc为原料，采用乳液聚合的方法合成了一种新型的不含烷氧基的水溶性W／O原油破乳剂SYL-01。反应条件与反应物的用量研究表明：反应物最佳配比为AA：MAA：BuAc：MMAC＝0．75：0．25：10：4。对原油乳液的破乳实验说明：SYL－01与目前使用的9901破乳剂性能相当，脱水率较高。SYL－01原料价廉易得，不使用易燃易爆的气体原料，工艺简单，有较好的开发应用前景。     

危险气体扩散实时仿真的关键技术──“反求源强”方法初探

阐述了计算机实时仿真在危险气体泄漏扩散预警系统中的应用。文中首次提出了通过求解气体扩散方程一类反问题来确定源强，即根据传感器实时检测的浓度值，代入反问题算法的仿真程序求得近似泄漏强度，再将实时采集的气象参数一并代入扩散方程，在显示屏上给出有害气体云团在区域电子地图上的扩散态势。     

MODELING THE EFFECT OF BRUSH CONTROL ON RANGELAND WATER YIELD1

ABSTRACT: With the increase in water demand in Texas, attention has turned to improving water yield by brush control on rangeland watersheds. Several hydrologic models have been developed for either farmland or rangeland. However, none of the models were specifically developed to assess the impact of brush control on rangeland water yield. Yet, modeling the impact of brush control on water yield needs to be considered if alternative techniques are to be compared. Two models, Ekalaka Rangeland Hydrology and Yield Model (ERHYM-II) and Simulator for Water Resources on Rural Basins (SWRRB) were selected. The Soil Conservation Service curve number (SCS-CN) method is used in both models to predict surface runoff from each rainfall event. The major differences between the ERHYM-II and SWRRB models are the evapotranspiration, soil water routing, and plant growth components. The models were evaluated on brush-dominated and chemically and mechanically brush-controlled range watersheds in Texas. Results indicated that both models were capable of simulating soil water and water yield from brush dominated and chemically brush-controlled range watersheds. The models were not able to predict water yield from the mechanically brush-controlled (root plowed) watershed with acceptable accuracy. The depressions that were caused by root plowing stored surface runoff and reduced water yield from the watershed. Information about the size of depressions was not available for further model evaluation.