Atmospheric lead transport

Chapter 6 was concerned, with determining the probability of various failures leading to insufficient core cooling of a nuclear reactor. This chapter describes how the accident effects are calculated as the accident progresses from radionuclide release, radionuclide migration within the plant, escape from retaining structures, atmospheric radionuclide transport and the public health effects. 

A significant amount of lead emitted in a country is transported beyond the national borders contributing to the trans-boundary transport. In 2002 as much as 4.8 kt (around 60% of total anthropogenic emission) of atmospheric lead, emitted in Europe were involved in transport across state borders. Absolute magnitudes of lead transported outside countries vary substantially from country to country. It was calculated as difference between national emission and deposition to the country. This magnitude depends on national emission, size of the territory, climatic conditions and spatial distribution of emission sources within the country. 

The highest amount of lead transported across the state borders, is coming from Russia, followed by Turkey and Italy. This can be explained mainly by the significant absolute values of lead atmospheric emissions in these countries. About 1500 t of lead was transported from the European Union. It should be noted that more than 75% of lead mass involved in the trans-boundary transport is emitted by 10 major countries-contributors. 

As shown in Table 28.9, human activities are presently responsible for most of the lead transported to the atmosphere, rivers, and oceans. The majority of this lead is mobilized by the burning of leaded gasoline, the refining of ores, and the burning of coal. More than 90% of environmental Pb is a result of past anthropogenic activities. Although... 

This figure depicts fate and transport among environmental compartments for a chemical element. Lead, being an element, cannot be destroyed or created in its environmental lifetime, and its relative mobility has little effect on its overall environmental survival. Consequently, significant movements of atmospheric lead to receiving compartments such as soils during past years are stiU relevant for today s lead exposure assessments regardless of marked declines in current air lead emissions and lead deposition to soils. 

EPA, 2006). Reentrainment of lead in particulate back into the atmosphere from dusts and soils after initial deposition of lead from the atmosphere also occurs due to atmospheric mobilization (Cowherd et al., 1985 U.S. EPA, 2006). The range of lead transport via the atmosphere can be many miles for the smallest size particles to as short as meters for reentrained dust particles at roadways for heavy traffic or for large lead paint particles, as occurs with weathering and flaking of lead-painted surfaces in older buildings where particles are mobilized to nearby soil surfaces, around the drip line."... 

Our own approach is somewhat different and emphasizes spectra produced by thermal emission from planetary atmospheres, especially as observed from space platforms. In order to demonstrate the connection between the thermal radiation giving rise to these spectra and the physical state of the atmosphere under consideration, it is necessary to examine how the transport of this radiation is effected. Only then is it possible to have a clear understanding of how the structure of an atmosphere leads to its spectral appearance, a topic considered at length in Chapter 4. Once this is accomplished a reversal of the procedure is feasible, and in Chapters 6 through 9 we demonstrate how the observed characteristics of the radiation field imply the underlying physical structure and the state of the interacting atmosphere. 

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