Electroosmotic dewatering of dredged sediments: bench-scale investigation

The Indiana Harbor (Indiana, USA) has not been dredged since 1972 due to lack of a suitable disposal site for dredged sediment. As a result of this, over a million cubic yards of highly contaminated sediment has accumulated in the harbor. Recently, the United States Army Corps of Engineers (USACE) has selected a site for the confined disposal facility (CDF) and is in the process of designing it. Although dredging can be accomplished rapidly, the disposal in the CDF has to be done slowly to allow adequate time for consolidation to occur. The sediment possesses very high moisture content and very low hydraulic conductivity, which cause consolidation to occur slowly. Consolidation of the sediment is essential in order to achieve adequate shear strength of sediments and also to provide enough air space to accommodate the large amount of sediment that requires disposal. Currently, it has been estimated that if a one 3-foot (0.9-m) thick layer of sediment was disposed of at the CDF annually, it would take approximately 10 years to dispose of all the sediment that is to be dredged from the Indiana Harbor. This study investigated the feasibility of using an electroosmotic dewatering technology to accelerate dewatering and consolidation of sediment, thereby allowing more rapid disposal of sediment into the CDF. Electroosmotic dewatering essentially involves applying a small electric potential across the sediment layer, thereby inducing rapid flow as a result of physico-chemical and electrochemical processes. A series of bench-scale electrokinetic experiments were conducted on actual dredged sediment samples from the Indiana Harbor to investigate dewatering rates caused by gravity alone, dewatering rates caused by gravity and electric potential, and the effects of the addition of polymer flocculants on dewatering of the sediments. The results showed that electroosmotic dewatering under an applied electric potential of 1.0VDC/cm could increase the rate of dewatering and consolidation by an order of magnitude as compared to gravity drainage alone. Amending the sediment with polymers at low concentrations (0.5-1% by dry weight) will enhance this dewatering process; however, the optimal polymer concentration and the cost-effectiveness of using polymers should be investigated further.     

China's small coal mine policy in the 2000s: A case study of trusteeship and consolidation

China has been trying to improve the safety and environmental performances of small coal mines (SCMs) in 2000s through measures of trusteeship and consolidation. The question whether such policy and practice can sustain small scale mining is interesting academically and important practically for China and the world. This paper finds that the Chinese SCM policy has been switched from encouragement to restriction for legal SCMs and from privatization to nationalization in some provinces in the past 10 years. Legal SCMs face pressure to be expanded continuously and to be absorbed or consolidated by large coal mines, which often are state owned. Unexpectedly, financial resources may not be a big constraint nowadays due to availability of private equity investment resources. The paper argues that both the trusteeship and consolidation approaches may only be able to sustain SCMs in the short run. A more sustainable measure is to establish a stable, transparent and inclusive legal and fiscal framework. This paper concludes that those trusteeship approaches may be applicable to restructuring small scale mines in other countries; however, the consolidation practice in China's is unique and thus may not be applicable to others.     

浅述市场经济下的安全生产

在建立社会主义市场经济过程中 ,难免出现经济秩序混乱、恶性竞争、忽视安全生产、规章制度不健全、事故多发等现象。如何有效遏制事故多发 ,促使安全生产长治久安 ,切实保障人民群众生命财产安全是社会各界关注的话题。通过对西昌市凉山州安全生产现状的分析 ,笔者认为 ,理顺体制、健全法治、依法严治、提高人民安全意识是市场经济条件下安全生产切实可行的长效监管机制     

Consolidation in an Individual Transferable Quota Regime: Lessons from New Zealand, 1986–1999

Market-based approaches to environmental regulation (such as tradable permits or transferable quotas) are frequently offered as innovative solutions to many environmental problems. Globally, one of the most well-established forms of this approach is individual transferable quotas (or ITQs) in fisheries management. Within the natural resource management community, there is considerable debate over the effects ITQs have on the fishing industry and fisher behavior although this approach is not well-established in the United States. The previously imposed moratorium on ITQs in the United States has expired and the 2006 reauthorization of the Magnuson-Stevens Act explicitly provides for limited access privileges (LAPs). A variety of fishers, regulators, and conservation organizations are enthusiastically seeking to introduce ITQ management. With debate over whether and how ITQs should be used in American fisheries reinvigorated, it is timely to examine the evidence on the social and economic effects of ITQs in other nations’ fisheries. After briefly summarizing the debate on ITQs, we examine the case of New Zealand, one of the earliest and longest-lived ITQ-based fisheries regimes. We use multiple data sources and methods to analyze the extent to which industry consolidation and aggregation has occurred, including surveys of industry participants, expert interviews, reviews of academic reports and analyses, analysis of trade publications, and direct analysis of quota ownership patterns. This analysis shows a more complex outcome than recent debates in the ITQ literature would predict. These findings suggest that policy makers considering ITQs can learn from the experiences of other countries related to key issues such as quota allocation, aggregation limits, transferability, cost recovery, and resource sustainability when designing ITQ and other LAP systems. It is also important to explicitly identify economic and social objectives and then carefully design ITQ regimes to meet these objectives.     

钢筋混凝土大槽瓦自防水屋面防水加固

对钢筋混凝土大槽瓦自防水屋面防水缺陷进行了分析,并提出了独到的加固方法。