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排序方式: 共有110条查询结果,搜索用时 15 毫秒
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The objective of this study was to estimate the contribution of a facility that processes steel production slag into raw material for cement production to local outdoor particle deposition in Camden, NJ. A dry deposition sampler that can house four 37-mm quartz fiber filters was developed and used for the collection of atmospheric particle deposits. Two rounds of particle collection (3-4 weeks each) were conducted in 8-11 locations 200-800 m downwind of the facility. Background samples were concurrently collected in a remote area located -2 km upwind from the facility. In addition, duplicate surface wipe samples were collected side-by-side from each of the 13 locations within the same sampling area during the first deposition sampling period. One composite source material sample was also collected from a pile stored in the facility. Both the bulk of the source material and the < 38 microm fraction subsample were analyzed to obtain the elemental source profile. The particle deposition flux in the study area was higher (24-83 mg/m2 x day) than at the background sites (13-17 mg/m2day). The concentration of Ca, a major element in the cement source production material, was found to exponentially decrease with increasing downwind distance from the facility (P < 0.05). The ratio of Ca/Al, an indicator of Ca enrichment due to anthropogenic sources in a given sample, showed a similar trend. These observations suggest a significant contribution of the facility to the local particle deposition. The contribution of the facility to outdoor deposited particle mass was further estimated by three independent models using the measurements obtained from this study. The estimated contributions to particle deposition in the study area were 1.8-7.4% from the regression analysis of the Ca concentration in particle deposition samples against the distance from the facility, 0-11% from the U.S. Environmental Protection Agency (EPA) Chemical Mass Balance (CMB) source-receptor model, and 7.6-13% from the EPA Industrial Source Complex Short Term (ISCST3) dispersion model using the particle-size-adjusted permit-based emissions estimates.  相似文献   
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We conducted an online survey (n = 3321) followed by five focus groups with Forest Service employees involved in compliance with the National Environmental Policy Act (NEPA) to explore agency views of how NEPA should be implemented within the agency. We filter these perceptions through the lenses of different functional groups within the agency, each with its own role in agency compliance with NEPA and its own suite of perceived accountabilities. In doing so, we uncover areas of consensus regarding valued practices as well as tensions between employees with different roles in NEPA compliance. General consensus exists regarding the importance of the effective functioning of interdisciplinary teams, but opinions about what constitutes an effective team vary. Findings suggest that NEPA serves as a playing field for competing accountabilities felt by line officers, disciplinary specialists, and advisory personnel within the agency, as each attempts to exert influence over NEPA processes and their outcomes.  相似文献   
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To understand contaminant transport in aquatic systems, it is essential to define the physical characteristics of the primary particulate carriers. The distribution of organic pollutants with particle-size class and particle morphology in a freshwater embayment (Hamilton Harbor, western Lake Ontario) was studied using a sequence of novel sample preparation and characterization techniques. Water samples (24 L) were fractionated according to particle-size distribution using differential cascade sedimentation and centrifugation methods. These size fractions were subsequently subjected to a physicochemical characterization using scanning transmission electron microscopy and energy-dispersive spectroscopy to identify flocs and individual colloidal particles in the size range of 1 nm to 1 mm in diameter. Analytical chemical analyses were performed to identify organic contaminants in extracts prepared from particle-size classes, including polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). The contaminant distribution trends were very similar for all compound classes studied; contaminants were primarily associated with fractions containing particles less than 2 mum in diameter. Morphological characterization of these fractions showed the majority of the particulates to be humic fractals. The results of this study show that contaminants in aquatic systems can be preferentially associated with specific types of particle carriers, the characteristics of which can be clearly defined in terms of size and morphology.  相似文献   
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Stern S  Sonesson U  Gunnarsson S  Oborn I  Kumm KI  Nybrant T 《Ambio》2005,34(4-5):402-407
To study future, sustainable production systems, a step-wise method was used to create three future scenarios for pig production based on different sustainability goals. The first scenario focused on animal welfare and the natural behavior of the animals. The second targeted low impacts on the environment and the efficient use of natural resources. The third scenario aimed at product quality and safety. Each scenario fulfilled different aspects of sustainability, but there were goal conflicts because no scenario fulfilled all sustainability goals. The scenarios were then parameterized. The environmental impact was calculated using the life-cycle assessment (LCA) methodology, and the economic cost was calculated from the same data set. The cost per kilo of pork was highest for the animal welfare scenario and similar for the other two scenarios. The environmental scenario had the lowest environmental impact, and the product-quality scenario the highest. The results are discussed based on different future priorities.  相似文献   
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Ecuadorian shrimp farmers suddenly found themselves in a contentious triangle with environmentalists and banana growers in a conflict that was crippling the Ecuadorian economy. The controversy concerned the Taura Syndrome, a disease allegedly caused by banana pesticides which was killing shrimp in the Gulf of Guayaquil. The shrimp farmers had responded by venturing into new areas to get out of the way of the pesticide runoff. The new areas happened to be populated by sensitive mangrove trees, which enraged the environmentalists. The dispute intensified when the parties lobbied other governments to ban one another's products. An innovative Ecuadorian dispute resolution organization intervened to help the parties think of the problem in a new way. They worked with the parties to pool their resources, so that they were working toward the same ends, rather than fighting against one another. The intervention succeeded in institutionalizing a new relationship between the shrimp farmers, banana growers, and environmentalists that has allowed the parties to resolve their conflict and to handle others over the long-term.  相似文献   
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A test method for masonry fireplaces has been evaluated during testing on six masonry fireplace configurations. The method determines carbon monoxide and particulate matter emission rates (g/h) and factors (g/kg) and does not require weighing of the appliance to determine the timing of fuel loading.The intralaboratory repeatability of the test method has been determined from multiple tests on the six fireplaces. For the tested fireplaces, the ratio of the highest to lowest measured PM rate averaged 1.17 and in no case was greater than 1.32. The data suggest that some of the variation is due to differences in fuel properties.The influence of fueling protocol on emissions has also been studied. A modified fueling protocol, tested in large and small fireplaces, reduced CO and PM emission factors by roughly 40% and reduced CO and PM rates from 0 to 30%. For both of these fireplaces, emission rates were less sensitive to fueling protocol than emission factors.  相似文献   
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