269 resultados para Dredging spoil
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Organic matter amendments are applied to contaminated soil to provide a better habitat for revegetation and remediation, and olive mill waste compost (OMWC) has been described as a promising material for this aim. We report here the results of an incubation experiment carried out in flooded conditions to study its influence in As and metal solubility in a trace elements contaminated soil. NPK fertilisation and especially organic amendment application resulted in increased As, Se and Cu concentrations in pore water. Independent of the amendment, dimethylarsenic acid (DMA) was the most abundant As species in solution. The application of OMWC increased pore water dissolved organic-carbon (DOC) concentrations, which may explain the observed mobilisation of As, Cu and Se; phosphate added in NPK could also be in part responsible of the mobilisation caused in As. Therefore, the application of soil amendments in mine soils may be particularly problematic in flooded systems. (C) 2012 Elsevier Ltd. All rights reserved.
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Tunnel construction planning requires careful consideration of the spoil management part, as this involves environmental, economic and legal requirements. In this paper a methodological approach that considers the interaction between technical and geological factors in determining the features of the resulting muck is proposed. This gives indications about the required treatments as well as laboratory and field characterisation tests to be performed to assess muck recovery alternatives. While this reuse is an opportunity for excavations in good quality homogeneous grounds (e.g. granitic mass), it is critical for complex formation. This approach has been validated, at present, for three different geo-materials resulting from a tunnel excavation carried out with a large diameter Earth Pressure Balance Shield (EPB) through a complex geological succession. Physical parameters and technological features of the three materials have been assessed, according to their valorisation potential, for defining re-utilisation patterns. The methodology proved to be effective and the laboratory tests carried out on the three materials allowed the suitability and treatment effectiveness for each muck recovery strategy to be defined. © 2014 Elsevier Ltd.
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Estimate of dredging prices, July 14, 1854.
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Department of Physical Oceanography, School of Marine Sciences,Cochin University of Science and Technology
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We used a battery of biomarkers in fish to study the effects of the extensive dredging in Goteborg harbor situated at the river Gota alv estuary, Sweden. Eelpout (Zoarces viviparus) were sampled along a gradient into Goteborg harbor, both before and during the dredging. Biomarker responses in the eelpout before the dredging already indicated that fish in Goteborg harbor are chronically affected by pollutants under normal conditions compared to those in a reference area. However, the results during the dredging activities clearly show that fish were even more affected by remobilized pollutants. Elevated ethoxyresorufin-O-deethylase activities and cytochrome P4501A levels indicated exposure to polycyclic aromatic hydrocarbons. Elevated metallothionein gene expression indicated an increase in metal exposure. An increase in general cell toxicity, measured as a decrease in lysosomal membrane stability, as well as effects on the immune system also could be observed in eelpout sampled during the dredging. The results also suggest that dredging activities in the Gota alv estuary can affect larger parts of the Swedish western coast than originally anticipated. The present study demonstrates that the application of a set of biomarkers is a useful approach in monitoring the impact of anthropogenic activities on aquatic environments.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The purpose of this study is to provide a procedure to include emissions to the atmosphere resulting from the combustion of diesel fuel during dredging operations into the decision-making process of dredging equipment selection. The proposed procedure is demonstrated for typical dredging methods and data from the Illinois Waterway as performed by the U.S. Army Corps of Engineers, Rock Island District. The equipment included in this study is a 16-inch cutterhead pipeline dredge and a mechanical bucket dredge used during the 2005 dredging season on the Illinois Waterway. Considerable effort has been put forth to identify and reduce environmental impacts from dredging operations. Though environmental impacts of dredging have been studied no efforts have been applied to the evaluation of air emissions from comparable types of dredging equipment, as in this study. By identifying the type of dredging equipment with the lowest air emissions, when cost, site conditions, and equipment availability are comparable, adverse environmental impacts can be minimized without compromising the dredging project. A total of 48 scenarios were developed by varying the dredged material quantity, transport distance, and production rates. This produced an “envelope” of results applicable to a broad range of site conditions. Total diesel fuel consumed was calculated using standard cost estimating practices as defined in the U.S. Army Corps of Engineers Construction Equipment Ownership and Operating Expense Schedule (USACE, 2005). The diesel fuel usage was estimated for all equipment used to mobilize and/or operate each dredging crew for every scenario. A Limited Life Cycle Assessment (LCA) was used to estimate the air emissions from two comparable dredging operations utilizing SimaPro LCA software. An Environmental Impact Single Score (EISS) was the SimaPro output selected for comparison with the cost per CY of dredging, potential production rates, and transport distances to identify possible decision points. The total dredging time was estimated for each dredging crew and scenario. An average hourly cost for both dredging crews was calculated based on Rock Island District 2005 dredging season records (Graham 2007/08). The results from this study confirm commonly used rules of thumb in the dredging industry by indicating that mechanical bucket dredges are better suited for long transport distances and have lower air emissions and cost per CY for smaller quantities of dredged material. In addition, the results show that a cutterhead pipeline dredge would be preferable for moderate and large volumes of dredged material when no additional booster pumps are required. Finally, the results indicate that production rates can be a significant factor when evaluating the air emissions from comparable dredging equipment.
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Organic matter amendments are applied to contaminated soil to provide a better habitat for re-vegetation and remediation, and olive mill waste compost (OMWC) has been described as a promising material for this aim. We report here the results of an incubation experiment carried out in flooded conditions to study its influence in As and metal solubility in a trace elements contaminated soil. NPK fertilisation and especially organic amendment application resulted in increased As, Se and Cu concentrations in pore water. Independent of the amendment, dimethylarsenic acid (DMA) was the most abundant As species in solution. The application of OMWC increased pore water dissolved organic-carbon (DOC) concentrations, which may explain the observed mobilisation of As, Cu and Se; phosphate added in NPK could also be in part responsible of the mobilisation caused in As. Therefore, the application of soil amendments in mine soils may be particularly problematic in flooded systems.
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v.19:no.2 (1897)
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There is a puzzling, little-remarked contradiction in scholarly views of the European Commission. On the one hand, the Commission is seen as the maestro of European integration, gently but persistently guiding both governments and firms toward Brussels. On the other hand, the Commission is portrayed as a headless bunch of bickering fiefdoms who can hardly be bothered by anything but their own in ternecine turf wars. The reason these very different views of the same institution have so seldom come into conflict is quite apparent: EU studies has a set of relatively autonomous and poorly integrated sub fields that work at different levels of analysis. Those scholars holding the "heroic" view of the Com mission are generally focused on the contest between national and supranational levels that character ized the 1992 program and subsequent major steps toward European integration. By contrast, those scholars with the "bureaucratic politics" view are generally authors of case studies or legislative his tories of individual EU directives or decisions. However, the fact that these twO images of the Commis sion are often two ships passing in the night hardly implies that there is no dispute. Clearly both views cannot be right; but then, how can we explain the significant support each enjoys from the empirical record? The CommiSSion, perhaps the single most important supranational body in the world, certainly deserves better than the schizophrenic interpretation the EU studies community has given it. In this paper, I aim to make a contribution toward the unraveling of this paradox. In brief, the argument I make is as follows: the European Commission can be effective in pursuit of its broad integration goals in spite of, and even because of, its internal divisions. The folk wisdom that too many chefs spoil the broth may often be true, but it need not always be so. The paper is organized as follows. 1 begin with an elaboration of the theoretical position briefly out lined above. 1 then tum to a case study from the major Commission efforts to restructure the computer industry in the context of its 1992 program. The computer sector does not merely provide interesting, random illustrations of the hypothesis 1 have advanced. Rather, as Wayne Sandholtz and John Zysman have stressed, the Commission's efforts on informatics formed one of the most crucial parts of the en tire 1992 program, and so the Commission's success in "Europeanizing" these issues had significant ripple effects across the entire European political economy. I conclude with some thoughts on the fol lowing question: now that the Commission has succeeded in bringing the world to its doorstep, does its bureaucratic division still serve a useful purpose?
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Mode of access: Internet.