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1.
Nonlinear programming techniques are frequently used to design optimum monitoring networks. These mathematically rigorous techniques are difficult to implement or cumbersome when considering other design criteria. This paper presents a more pragmatic approach to the design of an optimal monitoring network to estimate human exposure to hazardous air pollutants. In this approach, an air quality simulation model is used to produce representative air quality patterns, which are then combined with population patterns to obtain typical exposure patterns. These combined patterns are used to determine ‘figures of merit’ for each potential monitoring site, which are used to identify and rank the most favorable sites. The spatial covariance structure of the air quality patterns is used to draw a ‘sphere of influence’ around each site to identify and eliminate redundant monitoring sites. This procedure determines the minimum number of sites required to achieve the desired spatial coverage. This methodology was used to design an optimal ambient air monitoring network for assessing population exposure to hazardous pollutants in the southeastern Ohio River valley.  相似文献   

2.
Continuous in-situ measurements of NMHCs at Mace Head, Ireland during two full annual cycles from January 2005 to January 2007 were used to investigate NMHC emission sources and transport including dilution and photochemical oxidation. The Mace Head research station is ideally located to sample a wide range of air masses including polluted European transport, clean North Atlantic and Arctic air masses and the ultra-clean, Southern Atlantic air masses. The variety in air mass sampling is used to investigate interaction of emissions, transport, dilution and photochemistry. Variability of long-lived hydrocarbon ratios is used to assess and estimate typical transport times from emission source to the Mace Head receptor. Seasonality in the ratios of isomeric alkane pairs (for butane and pentanes) are used to assess the effects of atmospheric transport and photochemical ageing. Finally, the natural logarithms of NMHC ratios are used to assess photochemical oxidation.  相似文献   

3.
为促进我国锌锰废电池集中资源化处理,开发了一种高温回收废电池中锰的新工艺.废电池分选后,破碎和筛分,其中二氧化锰与还原剂碳制成球团,烧结后在感应炉中还原锰,制成锰钢.实验表明,球团中不加表面活性剂的二氧化锰还原率为34%,球团中加入硫化物表面活性剂促进二氧化锰在钢中的还原率,达到80%,钢液中锰含量可达3.97%,本实验条件下,还原最佳时间为20 min.在铸钢生产中可以直接应用该工艺处理废电池.  相似文献   

4.
Bioaugmentation of contaminated sites with microbes that are adapted or genetically engineered for degradation of specific toxic compounds is an area that is currently being explored as a clean-up option. Biomarkers have been developed to track the survival and efficacy of specific bacteria that are used as inocula for bioremediation of contaminated soil. Examples of biomarkers include the luc gene, encoding firefly luciferase and the gfp gene, encoding the green fluorescent protein (GFP). The luc gene was used to tag different bacteria used for bioremediation of gasoline or chlorophenols. The bacteria were monitored on the basis of luciferase activity in cell extracts from soil. The gfp gene was also used to monitor bacteria during degradation of chlorophenol in soil, based on fluorescence of the GFP protein. Other biomarkers can also be used for monitoring of microbial inocula used for bioaugmentation of contaminated sites. The choice of biomarker and monitoring system depends on the particular site, bacterial strain and sensitivity and specificity of detection required.  相似文献   

5.
This paper describes the results of three experiments performed with Continuously Regenerating Traps (CRTs®) in a controlled laboratory setting to elucidate the effects of fuel sulfur content, filter age, and storage and release effects on particle concentration. In the first experiment, a new CRT was tested using near zero sulfur Fischer-Tropsch fuel and low sulfur lubricating oil (420 ppm). The objective was to measure particle emissions from an emission control device that had not previously been exposed to sulfur under a variety of operating and dilution conditions. Next, a used CRT was evaluated using the same fuel and lubricating oil. Finally, the used uncatalyzed Diesel particulate filter (DPF) from the used CRT was replaced with a new, uncatalyzed DPF. The emissions from the used Diesel oxidation catalyst (DOC) + new DPF were evaluated and compared to those of the used CRT.Our laboratory results show that particle number emissions from the new CRTs are 99.9% lower than equivalent used CRT data collected on-road at an exhaust temperature of 370 °C. Even as the new CRT temperature was increased to almost 400 °C, emission levels were still at background levels for roadway aerosol and no nucleation mode was observed. With the used CRT, the nucleation mode particle number concentration increased sharply at an exhaust temperature of about 380 °C and remained high for the duration of the test. Mass emissions were estimated and found to exceed US EPA on-road standards. The used DOC + new DPF led to essentially the same number emissions as the used CRT, suggesting that these emissions arise mainly from release of sulfates stored by the DOC and not the uncatalyzed DPF.  相似文献   

6.
Used engine oils contain metals, which upon entering soils may pose risks to human health or the environment. In this study, previously published concentrations of 23 metals in 213 used engine oil samples from the early 1970s to the mid-1990s are statistically evaluated. Neat (100%) used engine oils were found to contain relatively high concentrations of lead, calcium, and zinc, attributable to piston blow-by of leaded gasoline, calcium salt detergent additives, and zinc-bearing anti-corrosion/anti-oxidation additives, respectively. Wear metal concentrations were lower. The lead concentration in used engine oils in the U.S. declined between the 1970s and early 1990s, potentially providing a basis to constrain the “age” of used engine oil(s) in soils. The concentrations of 23 metals in used engine oils were compared to soil risk benchmarks in 15 representative jurisdictions in the U.S., Canada, Australia, and Europe. The maximum concentrations in neat (100%) used engine oil of eight metals – Be, Co, Fe, Mn, Ni, Se, Ag, and Ti – were lower than their collective minimum benchmarks in soils for the jurisdictions surveyed, indicating their concentrations in soils could not be reasonably expected to exceed any soil benchmarks. Nine metals (As, Ba, Cd, Cr, Cu, Pb, Sn, V and Zn), but particularly arsenic, cadmium, lead, tin, and zinc, were identified as potential contaminants of concern (PCOC) for soils from locations impacted with used engine oils, owing to their higher median concentrations (i.e., 2.5, 1.4, 1038, 5.0, and 922 mg/kg in oil, respectively) relative to most soil benchmarks. Site-specific benchmarks and metal concentrations at reasonable oil in soil concentrations require consideration when developing the suite of PCOC metal analytes for conducting site assessments of soils impacted by used engine oil.  相似文献   

7.
Back trajectory analyses are often used for source attribution estimates in visibility and other air quality studies. Several models and gridded meteorological datasets are readily available for generation of trajectories. The Big Bend Regional Aerosol and Visibility Observational (BRAVO) tracer study of July to October 1999 provided an opportunity to evaluate trajectory methods and input data against tracer concentrations, particulate data, and other source attribution techniques. Results showed evidence of systematic biases between the results of different back trajectory model and meteorological input data combinations at Big Bend National Park during the BRAVO. Most of the differences were because of the choice of meteorological data used as input to the trajectory models. Different back trajectories also resulted from the choice of trajectory model, primarily because of the different mechanisms used for vertical placement of the trajectories. No single model or single meteorological data set was found to be superior to the others, although rawinsonde data alone are too sparse in this region to be used as the only input data, and some combinations of model and input data could not be used to reproduce known attributions of tracers and simulated sulfate.  相似文献   

8.
汽车尾气净化催化剂的净化转化效果及其耐久性,与催化剂涂层的涂覆量以及涂层和载体的结合强度密切相关。本文研究了几种不同类型表面活性剂对浆料固体含量、涂层涂覆量以及涂层结合强度的影响。研究结果表明,不使用表面活性剂时,30%为最佳的固体含量;在使用表面活性剂的情况下,浆料的固体含量可以提高至35%。非离子型表面活性剂有助于提高催化剂涂层涂覆量,而使用离子型表面活性剂的浆料球磨过程中产生大量泡沫,无法涂覆。使用非离子型表面活性剂的催化剂涂层的结合强度最好。  相似文献   

9.
Sulfur hexafluoride (SF6) tracer was used in a series of the experiments to simulate emissions of benzene, toluene, ethyl-benzene, and xylenes (BTEX) from a refinery wastewater basin. The ratio of the measured tracer release to the ambient tracer concentration established a dilution factor which was then used to calculate the mass flux of BTEX from the wastewater basin using the ambient BTEX concentration data. Measured fluxes of BTEX varied from 7 g/min to 70 g/min.

The CHEMDAT7 air emissions model was then used to predict emissions for comparison with the emissions measured using the tracer flux simulation. CHEMDAT7 typically overpredicted total measured BTEX emissions by factors of twelve to seventeen. The degree of overprediction varied both by the individual compound and the module of CHEMDAT7 used to predict emission fluxes.  相似文献   

10.
汽车尾气净化催化剂的净化转化效果及其耐久性,与催化剂涂层的涂覆量以及涂层和载体的结合强度密切相关.本文研究了几种不同类型表面活性剂对浆料固体含量、涂层涂覆量以及涂层结合强度的影响.研究结果表明,不使用表面活性剂时,30%为最佳的固体含量;在使用表面活性剂的情况下,浆料的固体含量可以提高至35%.非离子型表面活性剂有助于提高催化剂涂层涂覆量,而使用离子型表面活性剂的浆料球磨过程中产生大量泡沫,无法涂覆.使用非离子型表面活性剂的催化剂涂层的结合强度最好.  相似文献   

11.
Environmental Science and Pollution Research - Camphor leaf (CL) was widely used to extract camphor oil and thus led to abundant forestry waste. In order to reduce pollution, the waste CL was used...  相似文献   

12.
Setback distance has been used as an effective tool to avoid odor nuisance from livestock operations. Many setback distances were guidelines that were determined by empirical methods that are considered to be lack of science base. Air dispersion models have been used to determine setback distances; however, these models do not consider the short-time fluctuations of odor. A livestock odor dispersion model (LODM) was developed to consider the short-time variations of odor and predict occurrence frequency for certain levels of odor. In this study, this model was used to predict the occurrence frequency for various levels of odor in the vicinity (10 km) of a swine farm. Using selected odor criteria, setback distances between the swine farm and nearby communities were defined. Results indicate that the LODM can be used as an effective tool to determine setback distances.  相似文献   

13.
14.
Soybean processing plants are typical of facilities in which solvent extraction is the major unit operation employed. Hexane solvent is used to treat soybeans, producing both a vegetable oil and a residue meal product. The hexane solvent is separated from the oil and the meal, recycled and used again in a closed loop fashion. At several points in the process vent streams are produced resulting in the atmospheric discharge of hexane vapor. This represents an air pollution problem and facilities are required to eliminate the problem. An economic analysis of pollution abatement requirements for soybean plants indicates that thermal incineration is the optimum system that can be used. However, at high levels of hexane content in the vent streams, a combination of activated carbon adsorption of the smaller stream plus thermal incineration of the larger stream should prove the most desirable form of pollution abatement. The analysis given in this report can be used to determine which pollution abatement system should be used, depending upon the hexane content of the vent streams.  相似文献   

15.
利用鄂尔多斯盆地白垩系的方沸石岩样,通过提纯和改性等处理制成多孔方沸石球,用于处理含氟水。用过的方沸石球经再生处理也用于处理含氟水。实验结果表明,多孔方沸石球和再生方沸石球都有明显的除氟效果。对于100mL浓度5.00 mg/L的含氟水,多孔方沸石球较佳的水处理工艺条件为:用量3.0 g,搅拌后静置48 h。对于浓度3.00 mg/L的含氟水,一次水处理就能将F-浓度降到国家标准以内,除氟效率达60%。对于浓度5.00 mg/L的含氟水,2次水处理可以将F-浓度降到国家标准以内,除氟效率达80%。多孔方沸石球对氟离子的吸附符合Langmuir等温式,吸附速度符合斑厄姆公式。再生方沸石球对氟离子的吸附也符合Langmuir等温式,吸附速度也符合斑厄姆公式。多孔方沸石球和再生方沸石球的饱和吸附量相当,这说明用过的方沸石球经再生处理后活性基本恢复,可循环用于含氟水的处理。  相似文献   

16.
To establish the quality of waters it is necessary to identify both point and non-point pollution sources. In this work, we propose the combination of clean analytical methodologies and chemometric tools to study discrete and diffuse pollution caused in a river by tributaries and precipitations, respectively.During a two-year period, water samples were taken in the Guadalquivir river (selected as a case study) and its main tributaries before and after precipitations. Samples were characterized by analysing nutrients, pH, dissolved oxygen, total and volatile suspended solids, carbon species, and heavy metals. Results were used to estimate fluvial and atmospheric inputs and as tracers for anthropic activities.Multivariate analysis was used to estimate the background pollution, and to identify pollution inputs. Principal Component Analysis and Cluster Analysis were used as data exploratory tools, while box-whiskers plots and Linear Discriminant Analysis were used to analyse and distinguish the different types of water samples.  相似文献   

17.
Dechlorinating agents and pH adjustment are often used to preserve wastewater samples for cyanide analysis. The effects of four approved preservation protocols on the results of the total cyanide analysis of effluents from four water reclamation plants were examined. The results differed widely, and a clear pattern emerged. Immediate analysis without pH adjustment generally gave total cyanide concentrations below the reporting limit of 5 microg/L, irrespective of the dechlorinating agents used. When the pH was adjusted to > or =12, a slight increase in the measured total cyanide concentration was observed when thiosulfate was used to dechlorinate the samples, and a significant increase (>10 microg/L) was observed when arsenite was used as the dechlorinating agent. These results provide evidence that approved preservation protocols may give rise to cyanide formation in chlorinated wastewater effluent matrices.  相似文献   

18.
The regulatory agencies and the industries have the responsibility for assessing the environmental impact from the release of air pollutants, and for protecting environment and public health. The simple exemption formula is often used as a criterion for the purpose of screening air pollutants. That is, the exemption formula is used for air quality review and to determine whether a facility applying for and described in a new, modified, or revised air quality plan is exempted from further air quality review. The Bureau of Ocean Energy Management’s (BOEM) air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. If a facility is not exempt after completing the air quality review, a refined air quality modeling will be required to regulate the air pollutants. However, at present, the scientific basis for BOEM’s exemption formula is not available to the author. Therefore, the purpose of this paper is to provide the theoretical framework and justification for the use of BOEM’s exemption formula. In this paper, several exemption formulas have been derived from the Gaussian and non-Gaussian dispersion models; the Gaussian dispersion model is a special case of non-Gaussian dispersion model. The dispersion parameters obtained from the tracer experiments in the Gulf of Mexico are used in the dispersion models. In this paper, the dispersion parameters used in the dispersion models are also derived from the Monin-Obukhov similarity theory. In particular, it has been shown that the total amount of emissions from the facility for each air pollutant calculated using BOEM’s exemption formula is conservative.

Implications:?The operation of offshore oil and gas facilities under BOEM’s jurisdiction is required to comply with the BOEM’s regulations. BOEM’s air quality regulations are used to regulate air emissions and air pollutants released from the oil and gas facilities in the Gulf of Mexico. The exemption formulas have been used by BOEM and other regulatory agencies as a screening tool to regulate air emissions emitted from the oil and gas and other industries. Because of the BOEM’s regulatory responsibility, it is important to establish the scientific basis and provide the justification for the exemption formulas. The methodology developed here could also be adopted and used by other regulatory agencies.  相似文献   

19.
The electronic computer has had a profound effect upon air pollution research activities. This paper discusses some of the ways in which Public Health Service scientists routinely make use of the computer. It is used as a data processor to handle the large volumes of data resulting from continuous air monitoring devices. More importantly, it is used to perform the very complex computations involved in various statistical analyses and mathematical model building. In future years computers may be used on a real-time basis to control the sources which emit pollutants to the atmosphere.  相似文献   

20.
The past 50 years have seen rapid development of new building materials, furnishings, and consumer products and a corresponding explosion in new chemicals in the built environment. While exposure levels are largely undocumented, they are likely to have increased as a wider variety of chemicals came into use, people began spending more time indoors, and air exchange rates decreased to improve energy efficiency. As a result of weak regulatory requirements for chemical safety testing, only limited toxicity data are available for these chemicals. Over the past 15 years, some chemical classes commonly used in building materials, furnishings, and consumer products have been shown to be endocrine disrupting chemicals – that is they interfere with the action of endogenous hormones. These include PCBs, used in electrical equipment, caulking, paints and surface coatings; chlorinated and brominated flame retardants, used in electronics, furniture, and textiles; pesticides, used to control insects, weeds, and other pests in agriculture, lawn maintenance, and the built environment; phthalates, used in vinyl, plastics, fragrances, and other products; alkylphenols, used in detergents, pesticide formulations, and polystyrene plastics; and parabens, used to preserve products like lotions and sunscreens. This paper summarizes reported indoor and outdoor air concentrations, chemical use and sources, and toxicity data for each of these chemical classes. While industrial and transportation-related pollutants have been shown to migrate indoors from outdoor sources, it is expected that indoor sources predominate for these consumer product chemicals; and some studies have identified indoor sources as the predominant factor influencing outdoor ambient air concentrations in densely populated areas. Mechanisms of action, adverse effects, and dose–response relationships for many of these chemicals are poorly understood and no systematic screening of common chemicals for endocrine disrupting effects is currently underway, so questions remain as to the health impacts of these exposures.  相似文献   

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