Prediction and minimization of vertical migration of DNAPLS using surfactant enhanced aquifer remediation at neutral buoyancy

Surfactant enhanced aquifer remediation (SEAR) had previously been thought to require a capillary barrier below the contaminated zone to prevent the vertical migration of a microemulsion containing solubilized DNAPL. This paper shows the vertical migration of the dense microemulsion is described and predicted by the value of three dimensionless scaling groups. Embedded within these scaling groups are four design parameters. The value of these parameters can be manipulated in order to reduce the amount of vertical migration anticipated for a given remediation design. Plots have been constructed that illustrate the relationship between vertical migration and the value of the scaling groups; such plots can be used to predict vertical migration and to determine appropriate screen intervals of extraction wells to ensure full capture of the contaminants. This predictive capability has been verified in laboratory experiments. Predicted migration of the microemulsion agreed within about 2% of that observed. Development of the scaling groups is presented, remediation design implications are discussed, and laboratory verification is shown. Additional discussion of the laboratory work is given in a companion paper [Kostarelos, K., Pope, G.A., Rouse, B.A., Shook, G.M., 1998. A new concept: the use of neutrally-buoyant microemulsions for DNAPL remediation, J. Contam. Hydro., this edition].     

由秦皇岛开发区第一次全国污染源普查谈污染源普查的质量保证

结合工业污染源普查的基层工作经历,分析污染源普查的特点和要求,对污染源普查的工作程序、工作方法等进行了探索性研究。针对实际工作中存在的问题提出解决方案,并在清查、普查环节提出了重点工作内容和工作方式的改进。     

Novel enzymatic activity of cell free extract from thermophilic Geobacillus sp. UZO 3 catalyzes reductive cleavage of diaryl ether bonds of 2,7-dichlorodibenzo-p-dioxin

We characterized the ability of the cell free extract from polychlorinated dibenzo-p-dioxins degrading bacterium Geobacillus sp. UZO 3 to reduce even highly chlorinated dibenzo-p-dioxins such as octachlorodibenzo-p-dioxins in incineration fly ash. The degradation of 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) as a model dioxin catalyzed by the cell free extract from this strain implicates that the ether bonds of 2,7-DCDD molecule undergo reductive cleavage, since 4′,5-dichloro-2-hydroxydiphenyl ether and 4-chlorophenol were detected as intermediate products of 2,7-DCDD degradation.     

A tool to aid emergency managers and communities in appraising private dam safety and policy

Issues concerning dam safety and equitable sharing of catchment run-off are receiving more attention throughout the world. This paper assesses these matters in the context of Australia, and the need for policy responses. Landholders often overlook the common law obligation to review/design dams to current standards because of high costs, leaving them vulnerable to litigation if their dam fails. The paper reports on an innovative spillway design/review procedure, applicable to southeast Australia, but transferable to any region worldwide. Dam safety policy models and guidelines derived from international best practice are linked to the procedure and intended to aid government decision-making. The procedure minimises costs to landholders and provides an acceptable level of safety assurance to downstream communities. Also discussed are recent surveys testing community attitudes to the procedure and implemented dam safety and water allocation policies. These further guide any government wanting to implement this'integrated engineering and community partnerships'approach to preventing potential disasters due to private dam failure and achieving sustainable and safe water storage and use.     

煤炭企业安全成本与安全投资比例优化分析

如何用最小的投资获取最大的效益,这是现代社会经济运行环境下提出的客观要求.同样,在煤炭企业的安全生产上,人们也希望用有限的安全投资,去实现企业尽可能高的安全水平,在获得可接受的安全水平下,尽可能去节约企业的安全投资,保证企业最大的经济效益.从安全经济学的角度论述煤炭企业的安全成本及安全投资比例,期盼找到煤炭企业安全和经济效益的最佳平衡点.     

固定污染源排气中颗粒物采样的质量保证

根据固定污染源排气中颗粒物采样的误差来源,提出质量保证措施。     

美国环境监测QA/QC的进展及对我们的启示

本文着重介绍质量保证与质量控制在环境监测中(特别是有机物监测中)应用的意义。美国环境保护部门对质量保证与质量控制是如何认识和行动的,我国环境保护部门对质量保证与质量控制的认识,以及本文作者分别就自己的经验谈对QA/QC的体会,和在监测科研中对我国各级环境监测实验室推行QA/QC的建议。      

红外光度法测定水中石油类的质量保证和质量控制探讨

质量控制是保证监测数据质量的重要环节,根据红外光度法测定石油类的原理,对影响数据的关键因素(如仪器校正系数、试剂、空白试验、方法检出限以及准确度的核查等)进行了讨论,对规范石油类的质量保证和质量控制有着实际意义。     

重庆市土地储备制度的融资选择

城市土地储备制度的运行必须以连续的资金流为保汪，但是传统的融资渠道，如财政拨款和银行贷款已不能满足当前城市土地整理及开发中巨大的资金需求。以重庆市为例，从分析重庆市城市土地利用状况和土地市场特点出发，运用PPP模式和ABS模式，提出土地信托和土地债券的概念，得出一条创新的城市土地储备制度融资渠道，以加强城市抵御各方面风险的能力。     

芦苇基和污泥基生物炭对水体中诺氟沙星的吸附性能

以芦苇秸秆和市政污水处理厂污泥为原料,在500℃的条件下制备了芦苇基和污泥基生物炭.利用比表面积测定法(BET)、扫描电镜(SEM)、能谱分析(EDS)和红外光谱(FTIR)研究了生物炭的结构与性质,并通过单因素实验研究p H、吸附时间、温度、诺氟沙星(NOR)初始浓度对吸附效果的影响,初步讨论了吸附机制.结果表明,NOR在芦苇基和污泥基生物炭上的吸附在12 h分别达到总吸附量的70%、60%以上;芦苇基和污泥基生物炭对NOR的饱和吸附量分别为2.13 mg·g-1和2.09 mg·g-1;降低溶液p H有利于NOR的吸附;生物炭对NOR的吸附行为符合准二级动力学方程,其等温吸附曲线符合Langmuir方程.对吸附过程吉布斯自由能(ΔG)、焓(ΔH)以及熵(ΔS)的计算证明生物炭对NOR的吸附是自发的吸热反应;红外光谱分析表明,生物炭上较多含氧官能团为NOR的吸附提供了吸附点,有利于NOR分子与生物炭间形成作用力较强的氢键,氢键为NOR吸附在生物炭上的主导作用力.