Exhaust emissions particles

The major focus on the effects of exhaust emissions has been on the HC1 component and its role in ozone depletion and on the A1203 particles, which could provide a surface for the heterogeneous conversion of HC1 to active forms of chlorine. It has been proposed that if the HC1 were converted to photochemically active forms relatively rapidly, a mini ozone hole could form in the flight path of the vehicle (Aftergood, 1991 McPeters et al., 1991 Karol et al., 1992). 

Pt-Rh/AROs catalysts are widely used in automotive-exhaust emission control. In these systems, Pt is generally used for the oxidation of CO and hydrocarbons and Rh is active for the reduction of nitric oxide to N2. HRTEM and AEM show two discrete particle morphologies and Pt-Rh alloy particles (Lakis et al 1995). EM studies aimed at understanding the factors leading to deactivation, surface segregation of one metal over the other and SMSI are limited. There are great opportunities for EM studies, in particular, of surface enrichment, and defects and dislocations in the complex alloy catalysts as sites for SMSI. 

Road traffic emissions consist of particulate (PM) and gaseous emissions, with active carbonaceous products present in both phases. Particles contain potentially toxic components, such as polycyclic aromatic compounds (PAHs) and trace metallic elements [4-6], which are related to acute and chronic cardiovascular and respiratory diseases [7]. Some studies suggest that especially diesel exhaust emissions are responsible for cardiac hospital admissions [8] and for asthma and chronic bronchitis development in children [9] in densely populated cities. Also fine and coarse particles from non-exhaust sources have been associated with short-term mortality and morbidity [10-13]. 

Particles in nucleation mode are generally formed due to condensation of the vapour present in the exhaust gases and nucleation (gas-to-particle conversion) in the atmosphere after rapid cooling and dilution of exhaust emissions [31,32]. These particles originate mainly from unbumed fuel and lubricating oil consisting of sulphates, nitrates and organic compounds [33]. 

Transportation sources, particularly automobiles, are a major source of air pollution and include smoke, lead particles from tetraethyl lead additives, CO, nitrogen oxides, and hydrocarbons. Since the mid-1960s there has been significant progress in reducing exhaust emissions, particularly with the use of low-lead or no-lead gasoline as well as... 

Carraro, E., Locatelli, A. L., Ferrero, C., Fea, E., and Gilli, G. 1997. Biological Activity of Particle Exhaust Emissions from Light-Duty Diesel Engines. J. Environ. Pathol., Toxicol. Oncol, 16,101-109. 

Experimental. The sediment used in this study was obtained from Colma Creek, at Serramonte Boulevard between El Camino Real and Junipero Serra Boulevard, in the city of Colma, San Mateo County, California. Colma Creek was chosen because its entire course occurs within an area of urbanization, and the sediments are therefore of the type which normally come in contact with lead and other heavy metals. The main sources of lead, atmospheric fallout and rainfall runoff contain particulate matter from automobile exhaust emissions. Several shovels full of the bottom material were placed in a plastic container. In the laboratory, several kilograms of the material were wet-sieved, and the fraction passing through a 200-mesh sieve (particle diameter less than 74 ym) was placed in a 1-liter graduated cylinder containing a 1 M sodium phosphate solution. The silt fraction settles in this medium while the finer clay particles remain suspended. After several hours, this clay suspension was then decanted and a portion of the material saved for X-ray diffraction, as were portions of the sand and silt fractions. 

Sjogren, M., Li, H., Barmer, C., Rafter, J., Westerholm, R. and Rarmug, U. (1996) Influence of physical and chemical characteristics of diesel fuels and exhaust emissions on biological effects of particle extracts a multivariate statistical analysis of ten diesel fuels. Chem. Res. Toxicol., 9, V)1—2(T]. 

Zayed J., Bande H. and Gilles L. E., 1999. Characterization of manganese-containing particles collected from rile exhaust emissions of automobiles running with MMT additive. Environmental Science and Technology, 33 3341-3346. 

Composition and size distribution of the emitted particles depend on the contribution of the individual emission sources related with road traffic—in particular combustion and non-tail-pipe emissions. Tailpipe emissions are vehicle exhaust emissions which are produced during fuel combustion (including additives) and released through the vehicle tailpipe (Rogge et al. 1993 Cadle et al. 1999). The particles derived from tail-pipe emissions are mainly composed of EC and OC, thus average total carbon emission rates are usually very close to the PM mass emission rates. Inorganic anions account for some percent of total tail-pipe emissions, the contribution of the elemental fraction is also in the order of few percent. 

Typical dryer exhaust emissions are sulfur compounds such as hydrogen sulfide, carbon disulfide, carbonyl sulfide, and methyl and n-propyl mercaptans. In addition to ammonia, the only amine present is trimethyl amine. Since the emissions from the dryers contain considerable moisture at temperature of about 95°C, necessary means should be provided to remove most of this moisture and to cool the air before further odor treatment. Also, there may be dust particles in the cyclone exhanst that shonld be removed before effective odor measnres can be applied. This is normally... 

Rauch et al. [69] used LDI-MS to investigate the speciation of the platinum group elements (PGEs Rh, Pd, Pt) present in automobile emission particles, as well as in road dust and river sediments. Automobile exhaust releases particles contaminated with PGEs from the catalytic converters. LDI-MS could show the presence of PGEs in all the samples investigated at parts per trillion concentration levels. In addition, a clear association of the PGEs with cerium was found. Cerium is also a constituent of catalytic converters. 

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