Studies of air pollution in the municipal district of Sete Lagoas, MG using nuclear techniques / Estudos da poluição do ar do município de Sete Lagoas, MG utilizando técnicas nucleares

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Toxic metals, such as Ni, V, Zn, Cu, Cr, Mn and metalloids as As and Se and their compositions are associated mainly with the smaller diameter particulates present in the atmospheric aerosols. This fact is important, principally, when it concerns public health, because this is considered the breathable fraction of particles that can penetrate deeply into the lungs and cause damage to the alveoli. Once in the atmosphere the concentrations of trace metals, in general, show very low levels, the determination of the elementary composition of those particles requires the use of appropriate analytical techniques such as Particle Induced X-Ray Emission (PIXE), neutron activation analysis (NAA) and of X-rays fluorescence spectrometry (XRF), among others. The main objective of this study was the identification of the generating sources of suspended particles present in the atmospheric aerosols of the municipal district of Sete Lagoas, a medium sized urban center, where different types of industries are found. In order to achieve that, soil samples and of solid wastes generated by the main industries of the area were collected. These include the industries of pig iron production that uses charcoal, the extraction and/or improvement of limestone and the fabrication of concrete and ceramic products, as well as the amount of total suspended particles (TSP) and of PM10 particles (those with an aerodynamic diameter smaller then 10 mm). The measurement of the concentration of trace elements present in each one of the samples was accomplished using the NAA and XRF techniques and the determination of its mineralogical composition was carried out through the technique of X- ray diffraction. The analyses by NAA and XRF of the solid wastes and of soil showed that the predominant chemical elements in these samples are Al, Ba, Ca, Fe, K, Mg, Na, Ti and Zn. The mineralogical composition analysis indicated the outstanding presence of silicate (quartz, microcline) carbonates (calcite) and oxides of iron (hematite) in these samples. High levels of particulate concentrations were measured during the sampling period (01/11/2005 to 02/13/2005). The mass concentration results for TPS indicated that in 76% of the days the air quality was considered Inadequate or Bad. The PM10 results showed that in 53% of the days the air quality was considered Reasonable. The determination of the size distribution of the particles presented in the atmospheric aerosols suggested that approximately 80% of the particles possess smaller aerodynamic diameter than 2.5 m. The results of the neutron activation analysis showed that Al, Fe, Cl, Cu, K, Mg and Na are the predominant chemical elements in the TPS and Na, Cu, Fe, Ba, Cl, Eu and Sm in PM10. The analysis of the mineralogical composition by the method of X-ray diffraction indicated that calcite (>30%) and quartz (10 to 30%) are the most abundant minerals present in both, TPS and PM10. The receptor model used was the Main Component Analysis that identified three profiles of sources for TPS and four profiles for PM10. The results indicated that the pollutant sources that contribute the most for the degradation of the quality of the air in the region are: resuspended soil dust, industrial processes (pig iron production and the fabrication of concrete and ceramic products) and the burning of fossil fuels.

ASSUNTO(S)

aerossóis rejeitos industriais aerosol wastes aerosols sete lagoas poluição do atmosférica meio ambiente sete lagoas environment particles metodos experimentais e instrumentacao para particulas elementares e fisica nuclear material particulado análise por ativação neutrônica air pollution industrial wastes neutron activation analysis

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