Air particulate matter characterisation of a rural area in Portugal

An aerosol monitoring of a rural and an urban area was accomplished in the frame of an international project promoted by the IAEA. The Gent PM10 air sampler equipped with Norwegian Institute for Air Research (NILU) stacked filter units (SFU) was used for air particulate matter sampling. Filter loads were measured by gravimetry and elemental concentration analysis carried out with both PIXE and INAA techniques. In this work we report the results obtained in a rural area located at 30 km east of Oporto, near a coal fired power plant. The samples were collected from September 1995 to August 1996 on a twice a week basis. The use of complementary analytical techniques allowed to determine concentrations for 23 elements. Time variations for both total particulate mass and elemental concentrations are presented. Enrichment factors were calculated for the fine (PM < 2 mu m) and the coarse (10 > PM > 2 mu m) fractions. Principal Components Analysis was applied to infer particulate mass emission sources. Another Gent air sampler was installed at the same sampling site but under different working conditions. Time averages obtained with the two systems are also compared. The results obtained with the two collectors operating under different conditions suggest that the statistical distribution of pollutants can be accounted by taking the average of a week and therefore a weekly monitoring of airborne particulate matter is proposed. A factor related to the coal fired power plant emissions has been identified. Since the power plant is going to be converted from coal to natural gas combustion, the results now obtained are important for a future comparison. (C) 1998 Elsevier Science B.V.