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621.
A comprehensive technological copper cycle treating a series of life stages (mining and processing, fabrication, utilization, and end of life) has been constructed for sixteen countries on the European continent for the year 1994. In this paper we draw on that information to present country-level copper cycles for a sampling of the countries. We then compare the countries on the basis of their relative and absolute copper production, import/export, usage, recycling, and losses to the environment, and go on to produce per capita assessments of flow and stock changes. Among the results of particular interest are: (1) country-level copper budgets possess features often different from the continental budgets of which they are a part. For example, Europe extracted only slightly more copper from mines than it deposited in landfills, while the mine to landfill flow ratio was about 11:1 in Poland and near zero in the United Kingdom; (2) Germany led all other countries in the group of sixteen in the absolute magnitude of every major copper flow (production, import, export, consumption, and waste generation, and in per capita flows of copper entering use and waste management), while the Benelux countries led all others in per capita flows for all other categories; (3) citizens of essentially all the countries discarded 1–3 kg Cu/year, mostly in obsolete electronics and end-of-life vehicles.  相似文献   
622.
In this paper, a field study was carried out to examine the effect of flue gas desulfurization (FGD) by-product on water quality at an underground coal mine in central-eastern Ohio. Flue gas desulfurizalion by-product was injected into the down-dip portions of the Robert-Dawson mine in an attempt to seal major seeps exiting the mine and to coat exposed pyritic surfaces. Immediately following grout injection, significant increases in acidity, iron, aluminum, sulfur, and calcium were observed at most surface and ground water locations near where grouting was carried out. Following this initial flush of elements, concentrations of most constituents have decreased to near pre-grouting levels. Data from the site and geochemical modeling suggest that an increase in water level or rerouting of drainage flow resulted in the dissolution of iron and aluminum sulfate salts and ferrihydrite. Dissolution of the FGD grout material resulted in increases in calcium and sulfate concentrations in the drainage waters. Water within the mine voids was saturated with respect to calcium sulfate and gypsum immediately following grout injection. Based on an analysis of core samples obtained from the site, acid mine drainage (AMD) was in contact with at least some portions of the grout and this resulted in grout weathering. Subsequent transport of calcium and sulfate to the underclay, perhaps by fracture flow, has resulted in the deposition of gypsum and calcium sulfate solids.  相似文献   
623.
In order to prevent salinisation of the streams of the Riverine Plain of the Murray-Darling Basin in southern Australia, evaporation basins are used to dispose of saline irrigation drainage water. Local on-farm (individual landholder) and community (shared between multiple landholders) basins are increasingly being used to prevent export of salt outside irrigation districts. There are questions regarding the availability of land suitable for these basins and their impact on the surrounding environment. We describe the use of currently available spatial data to assist in regional planning for the environmentally safe use of these basins. A GIS-based approach was developed using suitability criteria expected to minimise the risk of off-site effects of basin leakage. The criteria were proximity to surface water features, urban areas and infrastructure, water table depth and salinity, and soil hydraulic conductivity. The approach was applied to all of the major irrigation districts at 1:250,000, the scale at which data are available over the entire Riverine Plain. Confidence in well-defined parameters such as proximity to infrastructure, urban areas and surface water features was higher than for those involving interpolated point data such as water table depth, salinity, and hydraulic conductivity. Most critically, hydraulic conductivity, the most important factor for basin leakage, was found to be unreliable at this scale. Use of higher resolution data (up to 1:100,000) available for two of the irrigation districts improved confidence in both water table depth and salinity but not in hydraulic conductivity. Despite these limitations, it was found that: (i) on-farm basins can only be used on an opportunistic basis in the eastern irrigation districts, but can be widely used in the western districts; (ii) community basins can be used anywhere there is suitable land; and (iii) the results raise serious questions as to whether there is enough suitable land in the eastern districts to dispose of all of the drainage water that is produced.  相似文献   
624.
Adopting a new paradigm for natural resource and environmental policy that emphasises continuous change, adaptation and learning demands a new approach to evaluation to enable improvements in the way these initiatives contribute to sustainable resource use. Evaluation is fundamental to identifying change, supporting an adaptive approach that is flexible enough to meet the challenge of change, and enabling learning at individual, community, institutional and policy levels. Based on a consideration of changing approaches to natural resource management (NRM) policy and observations and experiences in the practical assessment of on-the-ground initiatives, the authors develop a set of principles for evaluation in NRM that: (a) addresses evaluation from a systems perspective, (b) links objective to consequence, (c) considers the fundamental assumptions and hypotheses that underpin core policy or program objectives, (d) is grounded in the natural resource, policy/institutional, economic, socio-cultural and technological contexts of implementation in practice, (e) establishes practical and valid evaluation criteria by which change can be monitored and assessed, (f) involves methodological pluralism including both quantitative and qualitative methods to ensure rigour and comprehensiveness in assessment, and (g) integrates different disciplinary perspectives (i.e. social, economic, environmental, policy and technological). The paper develops a systems-based evaluation framework that incorporates these principles and also recognises the multiple levels and nested nature of NRM policy, namely: problem characterisation, policy formulation and intent, program logic, and on-ground implementation. Finally, we demonstrate its utility through application to three contrasting Australian case studies: a community-based Integrated Catchment Management policy implementation; a resource information delivery system; and the development of a Decision Support System.  相似文献   
625.
Contemporary approaches to natural resources and environmental decision-making typically draw on a “systems” perspective to assess and improve management strategies. This paper describes the early genesis of the systems analysis approach. It concentrates on a period between the mid-19th to early 20th centuries. During the early part of this period, George Marsh's Man and Nature and related works laid out an approach to problem-solving that recognized the relationship among physically disperse elements in the environment, the need to balance benefits against costs, the potential for using quantitative modeling to understand management options, and the importance of integrating human and natural components into solutions. In the early 20th century, the Miami Conservancy District project brought this approach to fruition with its use of complex simulation and optimization modeling, detailed cost–benefit analysis, and its linking of economics, engineering, science, and law into a far-reaching solution to a complex water resources problem. The objective of this paper is to describe the early development and application of this conceptual approach to problem-solving. An examination of the origins of natural resources systems analysis can broaden one's perspective of the contemporary field to understand its roots as a philosophy for environmental problem-solving.  相似文献   
626.
The Macrouridae are the most common fish caught in demersal trawls on the continental slope and rise of the Rockall Trough. They represented 41% of all fish caught, with Coryphaenoides rupestris amounting to 28% of the catch. No previous study of the trophic interaction of these fish has been made over a wide bathymetric range. Samples were obtained at 250-m intervals of depth between 400 and 2 900 m in the period 1975 to 1981. The stomachs of 5 326 fish belonging to 12 species were examined to define their diets. Eight species are primarily benthopelagic feeders while four are primarily epibenthic feeders. The bathymetric centres of distribution of the populations of the benthopelagic feeding Trachyrhynchus murrayi, Malacocephalus laevis, Coryphaenoides rupestis, C. guentheri, Nematonurus armatus, Chalinura brevibarbis, C. leptolepis and C. mediterranea are different from each other. Similar differences in bathymetric distribution occurred among the epibenthic feeding Nezumia aequalis, Coelorhynchus coelorhynchus, C. occa and Lionurus carapinus. These differences decrease competition among species that exploit similar resources.  相似文献   
627.
Most of the starch in starch-polyethylene-co-acrylic acid (EAA)-polyethylene (PE) composites prepared by injection molding was not accessible to starch-hydrolyzing enzymes. Even when these composites were treated with enzyme in the presence of Triton X-100 for 96 h, little starch hydrolysis was observed. However, when the starch-plastic material was pulverized, both the extent and the rate of starch hydrolysis increased dramatically, with about 70% hydrolysis of the starch within 18 h. Reactions carried out for up to 96 h showed that, while the enzyme was active, the reaction reached a plateau, achieving a total of 80% starch hydrolysis. Fourier transform infrared (FTIR) spectroscopy revealed that only starch, and not EAA or PE, was affected by enzyme in pulverized samples. Results indicated that while 80% of the starch in these composites was transiently inaccessible, perhaps due to EAA and PE forming an impermeable barrier to the enzyme, the other 20% remained inaccessible to enzymes. Also, the rate of starch digestion as determined by solubilized reducing sugar correlated with the particle size of the pulverized material, suggesting that a large available surface area is critical for rapid starch degradation in such composites.The mention of firms names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over the firms or similar products not mentioned. All programs and services of the U.S. Department of Agriculture are offered on a nondiscriminatory basis without regard to race, color, national origin, religion, sex, marital status, or handicap.  相似文献   
628.
629.
The effects of phosphate (P) and zeolite (Z) -built detergents on leaching of N and P through sand columns simulating septic system drainfields were examined in laboratory columns. To simulate mound septic system drainfields, paired sets of columns were dosed intermittently with septic tank effluent from households using P- or Z-built detergent. Two other paired sets of columns were flooded with P- or Z-effluent to simulate new conventional septic system drainfields; after clogging mats or “crusts” developed at infiltration surface, the subsurfaces of the columns were aerated to simulate mature (crusted) conventional septic system drainfields. NO3 loading in leachate was 1.1 times higher and ortho-P loading was 4.3 times lower when columns were dosed with Z- than with P-effluent. Dosed columns removed P poorly; total phosphorus (TP) loading in leachate was 81 and 19 g m−2 yr−1 with P- and Z-effluent, respectively. In flooded columns 1.3, 2.0 and 1.8 times more NH4, organic nitrogen (ON) and total nitrogen (TN) respectively, were leached with Z- than with P-effluent; NO3 leaching was similar. Flooded columns removed P efficiently; TP leached through flooded systems was 2.5 and 1.4 g m−2 yr−1 with P- and Z effluent, respectively. Crusted columns fed Z-effluent leached 1.2, 2.6, 1.4 and 2.1 times more NH4, NO3, ON and TN, respectively, than those with P-effluent but 1.8 times less TP. Crusted columns removed P satisfactorily: 8.2 and 4.6 g m−2 yr−1 TP with P- and Z-effluent, respectively. The P-built detergent substantially improves the efficiency of N removal with satisfactory P removal in columns simulating conventional septic system drainfield. Simultaneous removal of N and P under flooded conditions might be explained by precipitation of struvite-type minerals. Dosed system drainfields were less efficient in removing N and P compared to flooded and crusted system drainfelds.  相似文献   
630.
Environmental monitoring activities are examined from a perspective which focuses on the political, economic and social factors which shape what we know and do not know about local environments. A UK urban case study is used to examine the range of influences that can operate on local level monitoring and comparisons are then made with the situation in three other European cities. Conclusions are drawn which debate the appropriate balance between local discretion and national and international direction in the collection of environmental information. It is argued that scrutiny of and revisions to the quality of current environmental monitoring in the UK and wider debate over questions of purpose, scope and resource commitment are needed.  相似文献   
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