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131.
Windblown dust is known to impede visibility, deteriorate air quality and modify the radiation budget. Arid and semiarid areas with unpaved and unvegetated land cover are particularly prone to windblown dust, which is often attributed to high particulate matter (PM) pollution in such areas. Yet, windblown dust is poorly represented in existing regulatory air quality models. In a study by the authors on modeling episodic high PM events along the US/Mexico border using the state-of-the-art CMAQ/MM5/SMOKE air quality modeling system [Choi, Y.-J., Hyde, P., Fernando, H.J.S., 2006. Modeling of episodic particulate matter events using a 3D air quality model with fine grid: applications to a pair of cities in the US/Mexico border. Atmospheric Environment 40, 5181–5201], some of the observed PM10 NAAQS exceedances were inferred as due to windblown dust, but the modeling system was incapable of dealing with time-dependent episodic dust entrainment during high wind periods. In this paper, a time-dependent entrainment parameterization for windblown dust is implemented in the CMAQ/MM5/SMOKE modeling system with the hope of improving PM predictions. An approach for realizing windblown dust emission flux for each grid cell over the study domain on an hourly basis, which accounts for the influence of factors such as soil moisture content, atmospheric stability and wind speed, is presented in detail. Comparison of model predictions with observational data taken at a pair of US/Mexico border towns shows a clear improvement of model performance upon implementation of the dust emission flux parameterization. 相似文献
132.
Spalinger SM von Braun MC Petrosyan V von Lindern IH 《Environmental monitoring and assessment》2007,130(1-3):57-72
House dust has been identified as a major exposure medium for lead (Pb) in children. High levels of Pb in soil and house dust
have been recorded at the Bunker Hill Superfund Site (BHSS) in northern Idaho, an historic mining and smelting district. Soil
and dust remediation at the site was required; however, regional background soil and dust Pb levels had not been well characterized.
The objective of this survey was to determine background house dust Pb levels and to compare those levels with concentrations,
and dust and Pb loading rates measured at the BHSS. Soil and house dust samples were collected in five towns demographically
similar to the BHSS but unaffected by the mining industry. The background concentrations and loading rates were significantly
lower than those observed at the site. House age was a significant factor affecting background soil and house dust Pb concentrations
and loading rates. 相似文献
133.
机动车零部件产品通过防尘试验来验证产品质量的可靠性能,本文简单介绍了国内外机动车零部件产品IP防尘等级试验的基本要求,对防尘试验设备选型方面做出了一点探讨. 相似文献
134.
焊接车间烟尘特性及治理措施 总被引:6,自引:0,他引:6
焊接生产会产生烟尘,焊接烟尘给人体带来的危害是比较严重的,焊接烟尘的治理方法有多种,合理选用可使焊接生产变成绿色环保型作业. 相似文献
135.
García-Nieto PJ 《Journal of environmental management》2006,79(4):372-382
This paper studies the scavenging efficiencies of aerosol emissions from coal-fired power plants under different removal mechanisms (coagulation, heterogeneous nucleation and gravitational settling) as a function of time. It also analyses the ‘health impact’ of the aerosol before and after the above dynamic mechanisms by comparing the respirable dust fractions. The well-known equations of evolution are applied to an average PSD that represents the exhaust particulate emissions from coal-fired power plants (i.e. Aboño power plant in Asturias that belongs to Hidrocantábrico Group, S.A.). From this study it is inferred that respirable dust is scavenged with the greatest difficulty and when compared with the initial volume of respirable dust, roughly 20% remains after 18 h of gravitational settling. Therefore, gravitational settling is the main removal mechanism of respirable dust compared to condensation and coagulation. 相似文献
136.
137.
When aluminum magnesium alloy dust floats in the air, a certain ignition energy can easily cause an accidental explosion. To prevent and control the occurrence of accidental explosions and reduce the severity of accidents, it is necessary to carry out research on the explosion suppression of aluminum magnesium alloy dust. This paper uses a vertical glass tube experimental device and a 20 L spherical explosive experimental device to carry out experimental studies on the suppression of the flame propagation and explosion overpressure of aluminum magnesium alloy dust with melamine polyphosphate (MPP) and Al(OH)3. With increasing MPP and Al(OH)3 concentrations, the flame brightness darkened, the flame velocity and propagation distance gradually decreased, and Pmax and (dp/dt)max decreased significantly. When the amount of MPP added reached 60%, the flame propagation distance decreased to 188 mm, which is a decrease of 68%, and the explosion overpressure decreased to 0.014 MPa, effectively suppressing the explosion of aluminum magnesium alloy dust. The experimental results showed that MPP was more effective than Al(OH)3 in inhibiting the flame propagation and explosion overpressure of the aluminum magnesium alloy dust. Finally, the inhibitory mechanisms of the MPP and Al(OH)3 were further investigated. The MPP and Al(OH)3 endothermic decomposition produced an inert gas, diluted the oxygen concentration and trapped active radicals to terminate the combustion chain reaction. 相似文献
138.
为了对比径向外喷和轴向喷雾下的低阻文丘里振弦栅耦合除尘效果,以除尘效率和系统阻力为参照,选定喉管气速、振弦栅数、纤维丝间隙和喉管液气比进行单因素实验。结果表明2种喷雾方式的除尘效率和系统阻力的变化趋势相同。利用SPSS软件进行4因素3水平正交实验设计,在特定参数条件下,2种喷雾方式的因素影响排序相同,除尘效率为纤维栅数>纤维丝间隙>喉管气速>喷雾量;系统阻力为喉管气速>纤维栅数>纤维丝间隙>喷雾量;径向外喷最佳配置为喉管气速24 m/s、喷雾量2.3 L/min、2块间隙为0.8 mm纤维栅板;轴向喷雾为喉管气速28 m/s、喷雾量2.4 L/min、2块间隙为0.8 mm纤维栅板;在最优配置下的除尘性能为径向外喷>轴向喷雾。 相似文献
139.
140.
分析了沥青混凝土搅拌设备的构成以及生产沥青混凝土的工艺及烟尘特点;通过应用工程实例,指出袋式除尘器是沥青混凝土搅拌设备最理想的除尘系统之一。 相似文献