HR: 0830h
AN: GP41B-0048    [PDF]
TI: The magnetic way of quantifying road traffic pollution in atmospheric particulate matter
AU: * Spassov, S
EM: simo@spassov.ch
AF: Department of Geophysics, School of Geology P.O. Box 353-1 Aristotle University of Thessaloniki, Thessaloniki, 54124 Greece
AU: Egli, R
EM: egli@mag.ig.erdw.ethz.ch
AF: Institute of Geodesy and Photogrammetry, ETH Honggerberg, Zurich, 8093 Switzerland
AU: Heller, F
EM: heller@mag.ig.erdw.ethz.ch
AF: Institute of Geophysics, ETH Honggerberg, Zurich, 8093 Switzerland
AB: The steadily increasing number of motor vehicles requires continuous air quality monitoring in large urban and sub-urban areas. We present a fast and simple method for analysing samples of atmospheric particulate matter (PM) based on magnetic measurements, which is suitable for systematic pollution monitoring of extensive areas at low costs. Representative samples have been collected in Switzerland at sites with variable exposure to pollution sources. Atmospheric PM consists of natural and of anthropogenic components which both contain magnetic mineral fractions with specific magnetic properties. Our method relies on the analysis of the remanent magnetisation of PM samples. Detailed demagnetisation curves of anhysteretic remanent magnetisation (ARM) of these samples have been modelled using a linear combination of appropriate model functions, which represent the contribution of different magnetic mineral sources to the total magnetisation. Two magnetic components C1 and C2 with well-defined magnetic properties have been identified in all samples. The low-coercivity component C1 predominates in less polluted sites, whereas the concentration of the higher coercivity component C2 is large in urban areas. Once the coercivity distributions of C1 and C2 have been characterised, a simple method has been developed to quantify C1 and C2. This method is based on four-step demagnetisation curves, which can be measured in 12 minutes using a 2G cryogenic magnetometer with an in-line AF degausser. Our results are confirmed by independent chemical investigations at the same sites. The magnetic contribution of C2 is shown to be proportional to the chemically estimated total PM10 mass contribution of exhaust emissions. The mass concentration of traffic related elements in PM10 such as Fe, Ba, Cu, Mo, Br and elemental carbon also correlates with our results. Traffic is the most important PM pollution source in Switzerland: it includes exhaust emissions and abrasion products released by vehicle brakes. The good correlation found between component C2 and traffic-related PM sources underlines the usefulness of the fast and non-destructive magnetic methods for the quantitative estimation of urban pollution as a low-cost alternative to chemical analysis.
DE: 1512 Environmental magnetism
DE: 1519 Magnetic mineralogy and petrology
DE: 1540 Rock and mineral magnetism
DE: 1594 Instruments and techniques
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting