Lead emissions

Other Le d Smeltings Processes. Stricter regulations concerning lead emissions and ambient lead in ak levels (see Airpollution), and the necessity to reduce capital and operating costs have encouraged the development of alternative lead smelting processes to replace the sinter plant—blast furnace combination. 

The emissions from a gasoline-powered vehicle come from many sources. Figure 6-12 illustrates what might be expected from an uncontrolled (1960 model) automobile and a controlled (1983 or later model) automobile if it complies with the 1983 federal standards (7). With most of today s automobiles using unleaded gasoline, lead emissions are no longer a major concern. 

Lead is an element used in many industrial processes and also has been used in fuels and coatings. Tetraethyl lead was added to gasoline to improve performance as a motor fuel, and elemental lead was extensively used in paints and coatings to improve coverage and durability until the 1970s, when phase-out efforts began to reduce lead emissions to the environment. 

Relatively few countries report annual lead emission estimates. Of those that have, declining trends In lead emissions have occurred, such as In the US where total lead emissions have been reduced by 75% (26). 

The primary source of lead in the environment has historically been anthropogenic emissions to the atmosphere. In 1984, combustion of leaded gasoline was responsible for approximately 90% of all anthropogenic lead emissions. EPA phased out the use of lead alkyls in gasoline, however, and by 1990, auto emissions accounted for only 33% of the annual lead emissions (EPA 1996h). Use of lead additives in motor fuels was totally banned after December 31, 1995 (EPA 1996f). The ban went into effect on February 2, 1996. Atmospheric deposition is the largest source of lead found in soils. Lead is transferred... 

Between 1976 and 1995, ambient concentrations of lead in the United States declined by 97%. Between 1994 and 1995, national average lead concentrations remained unchanged at 0.04 pg/m3 even though lead emissions declined 1% (EPA 1996h). 

In 1982-1983, the baseline value for daily intake of lead by inhalation in a nonurban environment was estimated to be 0.5 pg/day for a 2-year-old child. The baseline value was based on an average atmospheric lead concentration of 0.1 pg/m3 and an indoor/outdoor lead concentration ratio of 0.5. In an urban environment, the indoor/outdoor ratio was assumed to be approximately 0.8 (EPA 1986a). Drastic reductions in the lead content of gasoline since 1986 have resulted in a 64% decrease in lead emissions to the atmosphere (see Section 5.4.1). 

Dalpra L, Tibiletti MG, Nocera G, et al. 1983. SCE analysis in children exposed to lead emission from a smelting plant. MutRes 120 249-256. 

In order to illustrate how the results finally mm out, examples for external costs induced by lead emissions and environmental and human health end points are presented here. The example presenting the external costs of lead emissions is more elaborate so as to give the reader an opportunity to follow a typical line of reasoning, while the generic table on typical external costs can be used as examples of final results from economic valuation studies. 

Table 14 Predicted lead emissions via leachate from Guiyu dumps, based on van Oers [33] ...

The assessment of lead contamination in Kazakhstan and Kyrgyzstan is based on the global lead emission inventory for 1990 (Pacyna et al., 1995), the only available dataset at the moment. Despite the fact that lead emissions have considerably changed worldwide in the last fourteen years, the outcomes of the assessment can illustrate the general character of the long-range trans-boundary lead pollution in the countries under consideration. 

Tetra-ethyl lead became the chosen fuel additive. Over many decades, lead emissions from car exhausts accumulated in urban ponds and water systems. Many waterfowl that live in urban areas experience lead poisoning. Lead is also dangerous to human health. 

Table 28.9 Sources. Global Lead Emission from Natural and Anthropogenic...

The migration of PAEs from the polymers leads emissions to the environment during their production, transport, storage, manufacture, use, and disposal [8, 15, 40, 69]. Once in the different environmental compartments phthalates are subject to photo degradation, biodegradation, aerobic and anaerobic degradation and, thus, generally do not persist in the outdoor environment [8, 70]. 

Consider the following direct quotation that describes lead concentrations in ice cores and hrn (loosely compacted granular snow) taken from a glacier at the Swiss-Italian border. Convert the direct quote into a summary of the work as it might appear in the Introduction section of a journal article on lead emissions in... 

Schwikowski, M. Barbante, C. Doering, T. Gaeggeler, H. W. Boutron, C. Schotterer, U. Tobler, L. Van de Velde, K. Ferrari, C. Cozzi, G. Rosman, K. Cescon, P. Post-17th-Century Changes of European Lead Emissions Recorded in High-Altitude Alpine Snow and Ice. Environ. Sci. Technol. 2004, 38, 957-964. 

The ban on the use of leaded gasoline in the 1970s produced one of the most successful episodes in the search for the control of air pollutants. As already noted, the concentration of lead in the air dropped dramatically and to very low levels within a matter of years after the ban was put into place. Currently, efforts to control lead emissions focus on improving the methods used to remove lead from air and water wastes of smelters, metal processing plants, and other such plants. The most common systems currently used are variations of traditional waste control techniques in which physical devices (such as baghouses) or chemical systems (such as precipitation reactions) are used to extract particles of lead from wastes. 

The residence time estimated from lead emissions and lead atmospheric concentrations was 11 hours. 

The relative contribution of primary and secondary carbon to urban aerosol is discussed in this paper. Some data from the ACKEX study in Los Angeles have been reexamined using new values for the carbon and lead emissions. Data on total carbon, elemental carbon and lead in fine particle samples collected in St. Louis are presented. Lead and elemental carbon have been shown to be useful tracers of primary carbonaceous aerosol. It is concluded that secondary carbon is most likely to be a significant portion of the urban carbonaceous aerosol in the summer and in the middle of the day. Secondary carbon can best be measured with short time resolution sampling (At 6h). 

More recently Cass, Boone and Macias constructed a very detailed carbon inventory for Metropolitan Los Angeles in order to estimate the amount of primary elemental and organic carbon in this urban area ( ). Over 50 source types were included in this emission Inventory. A particulate lead emission inventory was also constructed and used as a tracer for primary automotive exhaust. They compared the ratio of organic carbon to elemental carbon and lead from the emission estimates to that measured in the atmosphere during winter mornings. In that study the sampling time and location were chosen in order to measure... 

FIGURE 2.16 (a) Contribution of various sources to total anthropogenic Pb emissions in the United States in 1996. (b) Trend in lead emissions in the United States (from EPA, 1995, 1997). 

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