Leaded gasoline consumption

Figure 4 presents the important EPA emissions data on a five-year time scale from 1970 to 1995. In the 1970s and 1980s, it is clear that leaded gasoline consumption was the overwhelming... 

As with dry precipitation, a number of factors govern the rate of wet deposition lead removal rates. These include particle size, seasonality, altitude, amount of precipitation, and thermal inversion (Conko et al., 2004 Davidson and Rabinowitz, 1992 Miller and Friedland, 1994). Input rates of lead to the atmosphere affect rainwater lead content. Table 5.4 presents water lead levels for various areas over a broad time frame. There is a clear trend to lower levels with lower anthropogenic impact, and a clear trend with time. Compared to the 1960s and 1970s when leaded gasoline consumption was at a maximum in the United States, later years showed dramatic drops in lead content. 

The U.S. air lead levels are presented here for later periods as well. These later periods generally reflect decline in consumption of lead and consequently production of lead (U.S. EPA, 1986a, 2006). There was the major decline in leaded gasoline consumption due to regulatory restrictions leading to, first, a phasedown of the amounts of antiknock additive permitted in fuels in the 1980s and early 1990s, followed by an eventual phaseout. The numbers of point source lead emissions from primary and secondary lead smelters markedly declined as well. 

These data for U.S. locations with elevated roadway/outside dust lead residues in the era of high leaded gasoline consumption were largely replicated for non-U.S. findings in developed areas around the world with relatively large vehicular fleets and densely populated urban areas. Table 6.25 shows the case for locales in Europe, Asia, Canada, etc. 

TABLE 6.23 Illustrative U.S. Roadside Dust Lead Concentrations (tig/g) in the Period of High Leaded Gasoline Consumption ... 

The major focus on leaded gasoline consumption in controlling air Pb levels in... 

In 1978, 90% of the 1, 2-dibromoethane produced went into leaded gasoline for this purpose (Santodonato et al. 1985). Due to the increased regulation of leaded gasoline, the production and consumption of 1,2-dibromoethane has been and will continue to decrease in the future (Fishbein 1980 Santodonato et al. 1985). 

Figure 2-I2b shows the lead concentration as a function of depth in the same lake in this instance the large industrial source revealed by the high concentrations near a 60-cm depth in the core is superimposed on another source that rises gradually until approximately a 20-cm depth, and then declines steadily. This other source is believed to be lead deposition from leaded gasoline, whose consumption increased steadily from its introduction in the 1930s until it was phased out in the United States during the 1970s and 1980s.

Lead (Pb) is one of the ancient metals and has been used by humans for several thousand years. Lead plays an important role in the economy of all industrialized countries in the world. In the U.S., the industrial consumption of Pb is estimated to be about 1.3 million tons per year, with a concomitant annual emission of about 600,000 tons of Pb into the environment (NAS 1980). Additional amounts are added through mining, smelting, manufacturing, disposal, and recycling processes. Furthermore, until recently, huge amounts of Pb and its compounds had been emitted into the atmosphere as a result of leaded gasoline combustion. Consequently, lead is ubiquitous in our environment. 

The information presented in this paper is directed to those individuals concerned with the fuel consumption benefits associated with the use of leaded gasoline and the reduction of lead emissions to the atmosphere through the use of automotive lead traps. 

If the use of leaded gasoline is increased in Canada to obtain improved refinery efficiency and lower automotive fuel consumption, automotive lead traps offer a viable means to control lead emissions into the environment, if such control is considered necessary. 

Fig. 3 shows the effect on energy consumption of reducing the lead content of gasoline whilst maintaining constant gasoline consumption/production (i.e. 1,000 tons). This corresponds to a situation where permissible gasoline lead levels are restricted without any measures to reduce the octane requirements of the vehicle population. The curves for 0.60, 0.40 and 0.15 Pb/L are taken from the original CONCAWE report (2). If the lead is not added to the latter case, than the curve will be displaced to the left by 3 RON. 

With information from the para-state Mexican oil company, Petroleos Mexi-canos (PEMEX), Bravo (1987) estimated that just in the area of Mexico City and surroundings (Metropolitan Zone of Mexico City, or MZMC) and due to the use of leaded gasoline (known as nova ), more than 32 metric tons of lead per day (approximately 12,000 metric tons per year) were emitted to the air. Before 1981, an annual emission of 19,600 tons/year of lead was calculated for the same area corresponding to a consumption of leaded gas of 20 million mVyr (Bruaux and Svartengren 1985). These authors estimated the emission of lead for 1982 in 12,800 metric tons and, based on the controls on lead in gas that were supposed to be established at that time, predicted that this amount would be reduced to 4000 metric tons/yr by 1984. 

As is frequent in many countries, coastal waters in Mexico are the final destination of all wastewaters generated upstream of the rivers and on the land close to the coasts. In general, lead can be found in higher concentrations in estuarine areas this is due mainly to the disposal of industrial wastes and to the consumption of leaded gasoline. 

Virtually all lead consumed in leaded gasoline production becomes lead dispersed to the atmosphere as part of vehicular exhaust. That dispersal does not allow for any economic reclamation and the dispersed lead remains in the atmosphere or is transported into and out of other environmental compartments (next chapter). In the case of lead consumption in lead fuel additives, there is close overlap in the near term between lead consumed for additive production and lead dispersed to the atmospheric environment from actual use in gasoline. Lead fallout through dry and wet precipitation processes transports lead to other media. This topic is addressed in Chapters 5 and 6. 

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