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Aerosol CHEMICAL PROCESSES IN THE ENVIRONMENT_P2

A compilation of the most important aerosol chemical processes involved in known scientific and technological disciplines, Aerosol Chemical Processes in the Environment serves as a handbook for aerosol chemistry. Aerosol science is interdisciplinary, interfacing with many environmental, biological and technological research fields. Aerosols and aerosol research play an important role in both basic and applied scientific and technological fields. Interdisciplinary cooperation is useful and necessary. Aerosol Chemical Processes in the Environment uses several examples to show the impact of aerosol chemistry in several different fields, mainly in basic and atmospheric research. The book describes the most important chemical processes involved. | 20 Analysis of Atmospheric Aerosols in Large Urban Areas with Particle Induced X-ray Emission Javier Miranda CONTENTS Introduction.405 Urban Aerosols.406 Basic Principles of PIXE Analysis.406 Sampling Procedures.408 PIXE Studies and Results.408 Conclusions.411 References.412 INTRODUCTION Air pollution in urban areas is a growing problem due to the increase in their dimensions and the effects it may have on public health other living species buildings and visibility. Moreover there is a worldwide tendency toward having larger cities. Thus according to the World Almanac1 1994 there were 45 cities with more than 4 million inhabitants in 1985 going up to 52 in 1991. This process gives origin to a reinforcement in health problems as the number of pollutant sources becomes greater in concentrated areas and more people are exposed to the emissions of those sources. The pollutants produced in large urban areas are also transported to surrounding zones or even remote sites thus worsening the air quality in those places also. Among air pollutants atmospheric aerosols are a special kind that is receiving increased attention because besides the aforementioned effects they may be responsible for a global temperature decrease produced by radiation reflection.2 In particular fine aerosols those having dimensions below 2.5 pm are capable of scattering solar radiation efficiently while additionally they can enter the respiratory tract and be deposited deeply in the lungs. Atmospheric aerosols are normally studied with one or more analytical techniques 3 which include atomic absorption spectrometry AAS ion chromatography IC neutron activation analysis NAA inductively-coupled plasma spectrometries ICP X-ray fluorescence XRF and particle-induced X-ray emission PIXE . None of them is individually capable of giving full characterization of the aerosols. However for analysis of elements having atomic numbers larger or equal to 13 i.e. heavier than Mg PIXE is the most suitable technique.4