High-level waste disposal,ethics and thermodynamics     

Michael O. Schwartz 《Environmental Geology》2008,54(7):1485-1488

Moral philosophy applied to nuclear waste disposal can be linked to paradigmatic science. Simple thermodynamic principles tell us something about rightness or wrongness of our action. Ethical judgement can be orientated towards the chemical compatibility between waste container and geological repository. A container-repository system as close as possible to thermodynamic equilibrium is ethically acceptable. It aims at unlimited stability, similar to the stability of natural metal deposits within the Earth’s crust. The practicability of the guideline can be demonstrated.  相似文献   

Impact of desalination plants brine injection wells on coastal aquifers     

Mohamed K. K. Nassar  Reda M. El-Damak  Ashraf H. M. Ghanem 《Environmental Geology》2008,54(3):445-454

A new methodology is developed in assessing environmental impacts of desalination plants discharging brine into the ground. The main environmental problem of the desalination of seawater is the brine disposal. The brine is commonly discharged into the sea or injected into a saline aquifer. In the case of injection into the ground, it is necessary to design a disposal system in a way that respects the environment and is sustainable. Laboratory and computational methods have been utilized to simulate the unsteady three-dimensional (3D) phenomena of subsurface brine disposal. The computational software used is SEAWAT, which is a 3D unsteady variable-density flow simulation model. The model is first used to simulate the laboratory results, and good agreement is achieved. Then, hypothetical problems are designed and simulated of groundwater extraction and brine disposal by desalination stations. The major purpose of these hypothetical problems is to delineate a methodology and to create design charts for design and management of production and injection well fields for coastal desalination plants. Several design charts have been developed with 36 scenarios for two well configurations created by four design parameters: relative salt concentration (RSC), production and injection rates (Q _d , Q _r ), well spacing (S), and simulation period (T).  相似文献   

天然磁铁矿处理含Hg（Ⅱ）废水实验研究   总被引：14，自引：0，他引：14       下载免费PDF全文

赵谨  鲁安怀  姜浩  陈浩  郑德圣  侯华丹 《岩石矿物学杂志》2001,20(4):549-554

利用重金属离子可在水合金属氧化物和氢氧化物矿物表面产生吸陵作用的原理，进行了天然磁铁矿处理含Hg(Ⅱ）废水的实验研究，结果表明：当温度为25℃，吸附平衡时间为60分钟、试样用量为20g/L，试样粒径为200目以下、pH值为6.40，离子强度为零时，Hg(Ⅱ）初始浓度为1.12mg/L的溶液的吸附率可达98%，使废水中Hg(Ⅱ）的浓度达到国家排放标准。pH值、离子强度、粒径、试样用量、废水浓度、温度、时间均对Hg(Ⅱ）的吸附率有一定的影响，其中pH值的影响最大，Hg(Ⅱ）在天然磁铁矿上的吸附等温曲线不同于Langmuir和Freundlich等温曲线，而是表现为台阶段，符合分级离子/配位子交换等温曲线。  相似文献   

Leaching potential and redox transformations of arsenic and selenium in sediment microcosms with fly ash     

《Applied Geochemistry》2016

The unintended release of coal ash to the environment is a concern due to the enrichment of contaminants such as arsenic (As) and selenium (Se) in this solid waste material. Current risk assessments of coal ash disposal focus on pH as the primary driver of leaching from coal ash. However, redox speciation of As and Se is a major factor for their mobilization potential and has received much less attention for risk assessments, particularly in disposal scenarios where coal ash will likely be exposed to microbially-driven redox gradients. The aim of this study was to demonstrate the differences of aerobic and anaerobic conditions for the leaching of As and Se from coal ash. Batch sediment-ash slurry microcosms were performed to mimic an ash spill scenario and were monitored for changes in As and Se speciation and mobilization potential. The results showed that the dissolved As concentrations were up to 50 times greater in the anaerobic microcosms relative to the aerobic microcosms during the two week incubation. This trend was consistent with As redox speciation determined by X-ray absorption spectroscopy, which indicated that 55% of the As in the solid phase at the end of the experiment was present as As(III) (a more leachable form of arsenic relative to As(V)). In the aerobic microcosms, only 13% of the As was As(III) and the rest was As(V). More than half of the Se was present as Se(IV) in the original fly ash and in the aerobic microcosms, while in the anaerobic microcosms Se was gradually transformed to less soluble Se(0) species. Likewise, dissolved Se concentrations were up to 25 times greater in the aerobic microcosms relative to anaerobic conditions. While the overall observations of As and Se mobilization potential from coal ash were consistent with expectations for aqueous and solid phase speciation of these elements, the findings directly show the relevance of these processes for coal ash disposal. These results highlight the need to select appropriate environmental parameters to include in risk assessments as well as provide potential geochemical monitoring tools through the use of dissolved Se/As ratios to determine the redox conditions of ash storage and spill sites.  相似文献   

Polymetallic Nodule Mining, Waste Disposal, and Species Extinction at the Abyssal Seafloor     

Hjalmar Thiel  Gerd Schriever  Eric J. Foell 《Marine Georesources & Geotechnology》2005,23(3):209-220

The size of individual mining blocks for polymetallic nodule extraction seems to be rather small, not more than 100 km² in the French mining claim. Even when adding an additional resedimentation zone to the directly impacted area, the size of the affected seabed would remain below 200 km². We assume that even rare species in the abyss inhabit larger areas and propose discussions of the International Seabed Authority and other stakeholders for the different subregions on mining strategies from the perspective of exploitation versus species extinction and conservation. Although impacts of waste disposal at the abyssal seafloor are different from those of nodule mining, the 200 km² concept may also be applied.  相似文献   

金山污水排海对纳污海域水质影响的数学模拟   总被引：3，自引：0，他引：3  

国峰  张海平  李阳  韦鹤平 《海洋学研究》2007,25(4):81-85

采用数值模拟的方法,计算和分析了上海市金山区水域无污水排放、放流管深海正常排放、岸边紧急排放和污水未经处理直接排放4种不同排放方式对纳污海域水质的影响。结果表明,在金山邻近海域的水动力条件下,上述4种排放方式中,岸边紧急排放对近岸海域的污染最严重。在事故排放这一最不利工况时,金山排海工程所选定的排放口,紧急排放对纳污海域环境的影响仍然是有限的,不会影响到小金山岛等敏感水域的水质。  相似文献   

海水工厂化养鱼排污水处理的实验研究与工程设计   总被引：4，自引：0，他引：4  

徐宾锋  杜守思  朱杰  林旭升  陈志成 《海洋湖沼通报》2001,(3):70-77

本文从保护海洋环境出发，论述研究设计海水工厂化养鱼排污水处理工程的重要性，提出用光合细菌（PSB）和海藻试验研究工厂化养鱼排污水处理的效率、特性及副产品的综合利用。通过工程计算，设计出工艺流程图及光合细菌反应池、二沉池和海藻塘的工程容量。  相似文献   

A solution around a backfilled cavity in a low‐permeability poroelastic medium with application in in situ heating tests          下载免费PDF全文

L. Yu  G.J. Chen  E. Weetjens 《国际地质力学数值与分析法杂志》2017,41(1):3-29

Thermo‐hydro‐mechanical responses around a cylindrical cavity drilled or excavated in a low‐permeability formation are studied when the cavity is subjected to a time‐dependent thermal loading. The cavity is considered backfilled after it is supported by casing or lining. Solutions of temperature, pore water pressure, stress, and displacement responses are analytically formulated based on Biot's consolidation theory with the assumption that the backfilling material, supporting material, and surrounding low‐permeability formation are poroelastic media. The solution is expressed in Laplace space, and numerical inversion techniques are used to find field variables in the real‐time domain. After the solution is verified with the numerical results, it is applied in a large‐scale in situ heating test – PRACLAY heating test – for a predictive reference calculation and an extensive parametric study. Another medium‐scale in situ heating test – ATLAS III heating test – is also analyzed using the solution, which provides reasonable agreement with measurements. The new analytical solution proves to be a convenient tool for a good understanding of the resulting coupled thermo‐hydro‐mechanical behavior and is therefore valuable for the interpretation of measured data in engineering practices and for a rational design of potential radioactive waste repositories. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

超声改性对不同粘土去除藻华生物效率的影响     

姜文彬  俞志明  曹西华  邱丽霞  宋秀贤 《海洋与湖沼》2018,49(3):560-567

粘土表面改性方法是提高改性粘土絮凝有害藻华效率的关键。本文研究了超声改性法对粘土去除藻华生物效率的影响,对比分析了粘土颗粒在改性前后的粒度分布、扫描电镜图像以及表面电位等理化特征变化,进而初步探讨了超声改性的作用机制。结果显示,超声改性处理可以有效提高本研究中所试验五种粘土去除藻华生物能力。超声改性导致粘土颗粒粒径进一步减小,且超声时间越长,颗粒粒径越小;超声处理后的粘土粒度分布集中、颗粒均匀,延长超声处理时间可以有效提高增效效果。同时发现,超声改性后粘土颗粒的表面电位负电性变弱,降低了粘土颗粒与表面负电性藻细胞之间的静电斥力,从而提高了粘土对藻华生物藻细胞的絮凝去除能力。本研究探索了提高粘土去除藻华生物效率的新方法,为进一步增强改性粘土去除能力提供了参考。  相似文献   

化学作用下高庙子膨润土屏障性能演化行为     

陈永贵  李昆鹏  马婧  廖饶平  叶为民  王琼 《工程地质学报》2022,30(1):71-82

深地质处置库运营过程中,受地下水化学成分、可能泄露的核素等近场化学条件影响,膨润土工程屏障性能可能发生衰减。围绕化学作用下膨润土屏障性能的演化行为,以我国北山处置库预选场地为工程背景,以内蒙古高庙子膨润土为研究对象,首先介绍了高庙子膨润土的基本物理性质及北山预选场地近场化学条件;在此基础上,详细总结了化学作用下高庙子膨润土水力、力学及阻滞等屏障性能演化行为相关研究成果。结果表明:化学作用对膨润土持水、渗透特性的影响可分别依据渗透吸力及双电层理论解释;化学作用下膨润土膨胀力的衰减与其水化膨胀机制有关,化-力耦合及化-水-力耦合作用下膨润土变形特性因渗透固结、化学软化效应而发生改变;膨润土的吸附与扩散特性受核素浓度、离子环境、pH值等因素影响。最后,提出化学作用下膨润土屏障性能演化研究应重点关注的方向。  相似文献