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排序方式: 共有421条查询结果,搜索用时 15 毫秒
31.
Colten Craig E. Simms Jessica R. Z. Grismore Audrey A. Hemmerling Scott A. 《Regional Environmental Change》2018,18(2):371-383
Regional Environmental Change - Louisiana faces extensive coastal land loss which threatens the livelihoods of marginalized populations. These groups have endured extreme disruptive events in the... 相似文献
32.
Standard procedures for evaluating environmental impact involve comparison between before and after conditions or scenarios
or between treatment and control site pairs. In many cases, however, endogenous directional change (natural succession) is
expected to occur at a significant rate over the period of concern, particularly for manmade systems such as impoundments.
Static evaluations do not provide an adequate approach to such problems. A new evaluation frame is proposed. Nominal system
behavior over time is characterized by a stochastic envelope around a nominal trajectory. We show that both the state variance
and the sampling variance can change over time. In this context, environmental regulations can be framed as constraints, targets,
or conformance to ideal trajectories. Statistical tests for determining noncompliance are explored relative to process variance,
sample error, and sample size. Criteria are elucidated for choosing properties to monitor, sample size, and sampling interval. 相似文献
33.
Vaughan Shilton Paul Giess David Mitchell Craig Williams 《Water, Air, & Soil Pollution: Focus》2002,2(5-6):237-246
Settled dust has been collected inside the main foyers ofthree University buildings in Wolverhampton City Centre,U.K. Two of the three buildings are located in a streetcanyon used almost exclusively by heavy duty dieselvehicles. The dust was collected on adhesive carbonspectro-tabs to be in a form suitable for analysis byscanning electron microscope and energy dispersive X-rayanalysis. Using these analytical techniques, individualparticle analysis was undertaken for morphology andchemistry. Seasonal variations and variations due tolocation were observed in both the morphologicalmeasurements and chemical analysis. Many of the differencesappear attributable to the influence of road traffic, inparticular, the heavy duty diesel vehicles, travellingalong the street canyon. 相似文献
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Oxygen Release Compound (ORC®) is a patented formulation of intercalated magnesium peroxide that releases oxygen slowly when hydrated. ORC treatment represents a “low intensity” approach to site remediation. It provides a simple, passive, low-cost and long-term acceleration of aerobic natural attenuation and has been shown to cost-effectively reduce time to site closure. ORC is now a proven technology as evidenced by its five years of use on over 5,000 sites in 50 states and 11 countries, and the existence of a full body of independent, peer reviewed literature on its performance. The first applications of ORC were for the treatment of benzene, toulene, ethylbenzene, and xylene (BTEX) and other light petroleum hydrocarbon fractions. Use has now expanded to the treatment of heavier fractions such as heating oil and some of the Polycyclic aromatic hydrocarbons (PAHs). More recently. ORC has been used to bioremediate the highly mobile and problematic gasoline oxygenate methyl tertiary butyl ether (MTBE) and has been applied to sites impacted with nitroaromatics, chloroaromatics, and some of the lower-order chlorinated hydrocarbons that can be treated aerobically—most notably vinyl chloride. Since ORC is an insoluble powder, it can be packaged in material composed of a specially designed filter fabric. These “filter socks” are then contacted with contaminated groundwater via an array of wells or trenches. ORC can also be mixed directly with water to form a slurry for permanent injection applications in the saturated zone or dispersed in powdered form for the in-situ or ex-situ treatment of soil. A broad array of treatment points, in which ORC slurry is backfilled or injected, can be implemented with low-cost, small-bore push-point technologies to directly treat dissolved phase plumes and moderate levels of sorbed contaminants. Powder or slurry is traditionally used in the remediation of residual contamination at the bottom of contaminated soil excavations. © 1999 John Wiley & Sons, Inc. 相似文献
36.
Relative to manufacturing, service activities are often considered by planners and officials to generate considerably less environmental pollution. This hypothesis is tested by means of an examination of the economic linkages of both manufacturing and service activities and of the resulting direct and indirect emissions of five air pollutants per dollar of output in the California statewide air basin and in four regional basins within the state. Overall acceptance or rejection of the hypothesis depends in part on the particular pollutant and air basin considered but, most importantly, on the judgement as to what activities are to be considered as service activities.This paper is based on research sponsored by the California Air Resources Board under Agreement A7-143-30. 相似文献
37.
Polyacrylamide preparations for protection of water quality threatened by agricultural runoff contaminants 总被引:11,自引:0,他引:11
Entry JA Sojka RE Watwood M Ross C 《Environmental pollution (Barking, Essex : 1987)》2002,120(2):191-200
Waste streams associated with a variety of agricultural runoff sources are major contributors of nutrients, pesticides and enteric microorganisms to surface and ground waters. Water soluble anionic polyacrylamide (PAM) was found to be a highly effective erosion-preventing and infiltration-enhancing polymer, when applied at rates of 1-10 g m(-3) in furrow irrigation water. Water flowing from PAM treated irrigation furrows show large reductions in sediment, nutrients and pesticides. Recently PAM and PAM + CaO and PAM + Al(SO4)3 mixtures have been shown to filter bacteria, fungi and nutrients from animal wastewater. Low concentrations of PAM [175-350 g PAM ha(-1) as PAM or as PAM + CaO and PAM + Al(SO4) mixture] applied to the soil surface, resulted in dramatic decreases (10 fold) of total, coliform and fecal streptococci bacteria in cattle, fish and swine wastewater leachate and surface runoff. PAM treatment also filtered significant amounts of NH4, PO4 and total P in cattle and swine wastewater. This points to the potential of developing PAM as a water quality protection measure in combination with large-scale animal feeding operations. Potential benefits of PAM treatment of animal facility waste streams include: (1) low cost, (2) easy and quick application. (3) suitability for use with other pollution reduction techniques. Research on the efficacy of PAM for removal of protozoan parasites and viruses and more thorough assessment of PAM degradation in different soils is still needed to completely evaluate PAM treatment as an effective waste water treatment. We will present analysis and feasibility of using PAM, PAM + Al(SO4)3, and PAM + CaO application for specific applications. Our results demonstrate their potential efficacy in reducing sediment, nutrients and microorganisms from animal production facility effluents. 相似文献
38.
Richard A. Pircon MD Craig V. Towers Manuel Porto Stephen E. Gocke Thomas J. Garite 《黑龙江环境通报》1989,9(10):701-707
Fetal triploidy is commonly found in early pregnancy. The majority of these pregnancies spontaneously abort in the first trimester. Occasionally, the pregnancy progresses to the second and third trimesters. We reviewed the maternal serum alpha-fetoprotein (MSAFP), amniotic fluid alpha-fetoprotein (AFP), amniotic fluid acetylcholinesterase (ACHE), fetal pathology, and placental pathology in sex second-trimester pregnancies complicated by fetal triploidy. Four of these patients had MSAFP values greater than 7.5 multiples of the median (MoM). Five of six pregnancies had MSAFP values greater than 2.25 MoM. All five of these patients had a partial mole. Four patients had amniotic fluid AFP values greater than 2.0 MoM. Two fetuses had associated neural tube defects. These were the only patients with positive amniotic fluid ACHE. None of the other patients had fetuses with anomalies that are known to be associated with an elevated MSAFP. The elevated MSAFP appeared to be related to the presence of a partial mole. Two of the five cases with an MSAFP greater than 2.25 MoM did not have sonographic evidence of a significant anomaly. Therefore, karyotyping can be of benefit in evaluating patients with elevated MSAFP. 相似文献
39.
Craig Emerson 《Natural resources forum》1980,4(2):123-145
A wide range of fiscal measures for natural resource based projects are analyzed in this paper. Maximizing government revenue involves taxing heavily any rents generated in the project while retaining the incentive to invest. Recovery efficiency must also be preserved. Based upon the principles of resource economics and project appraisai a series of tests are derived and applied to alternative tax schemes in order to assess their efficiency in maximizing the present value of government revenues. The tests indicate that of the ten schemes examined, the most likely to achieve revenue maximization is a progressive resource rent tax incorporating a safeguard tapering provision and superimposed upon normal corporate income tax. Many commonly applied taxes are demonstrated to have serious distortionary effects on the investment decision and to fail to capture a large proportion of rents generated. Cet article analyse une gamme variée de mesures fiscales applicables aux projets concernant les ressources naturelles. L'optimisation des recettes de l'Etat implique une lourde imposition des revenus provenant du projet tout en continuant à encourager les investissements. L'efficacité de la relance doit aussi être maintenue. Sur la base des principes de l'économie des ressources et de l'évaluation des projets, une série de tests a été conçue et appliquée à des systèmes fiscaux alternatifs afin de permettre l'évaluation de leur efficacité en ce qui concerne l'optimisation de la valeur actuelle des recettes de l'Etat. Les tests indiquent que sur les dix systèmes examinés, le plus susceptible d'optimiser les recettes semble être un impôt progressif sur les revenus provenant des ressources qui incorpore une clause de garantie dégressive et qui vient s'ajouter à l'impôt sur le revenu des sociétés habituel. L'article démontre que de nombreux impôts habituellement appliqués présentent de sérieux effets de distortion ayant un impact sur la décision d'investir et qu'une grande proportion des revenus de ces projets échappe à l'imposition. En este artículo se analiza una gama amplia de medidas fiscales sobre proyectos relacionados con recursos naturales. Maximizar los ingresos fiscales requiere imponer fuertes impuestos sobre las rentas generadas por el proyecto manteniendo al mismo tiempo el incentivo para la inversión. Debe mantenerse también la eficiencia en la recuperación de los recursos en cuestión. Basado en principios de la economía de recursos y de evaluación de proyectos se derivan una serie de pruebas sobre esquemas alternativos de aplicación de impuestos con el objeto de evaluar la eficiencia de dichos esquemas en la maximización del valor presente del ingreso del gobierno por concepto de impuestos. Las pruebas indican que de los diez esquemas examinados, el que con mayor probabilidad va a maximizar el ingreso del gobierno es el impuesto progresivo sobre la renta del recurso con un provisión de salvaguarda la reducción de dicho impuesto, más un impuesto simultáneo sobre el ingreso de la empresa. Muchos de los esquemas de imposición comúnmente aplicados tienen serios efectos distortionadores sobre las decisiones de inversión y consecuentamente impiden la colección de una gran parte de las rentas generadas. 相似文献
40.