Source apportionment of airborne particulate matter using magnetic parameters as tracers in addition to chemical tracers on the biomonitoring of a petrochemical complex in the Metropolitan Area of São Paulo, Brazil

The Metropolitan Area of São Paulo (MASP), situated in the Southeast region of Brazil, is among the ten largest megacities in the world, and largely impacted by air pollution due to the mobile emission of a fleet of more than 7 million vehicles and industrial sources. Several methodologies have been used to determine the pollutants' composition in order to characterize and estimate the impact of different particulate matter sources. The current methodologies use trace element concentrations, ionic compound and organic compound analysis. Recently, studies applying magnetic techniques at different metropolis in the world have proved to be effective in spatial monitoring of particulate matter concentrations, with advantage of being a fast and non-destructive method, bringing important complementary information. These studies of environmental magnetism use leaves, tree barks, soil samples, dust collected directly from the automotive roads and standard aerosol filters as substrates. In the present research, tree bark samples collected as part of a previous environmental monitoring work in the region around a Petrochemical Complex, in the Southeast MASP, were analyzed. Sixty-five tree barks samples of two tree species were collected around the petrochemical complex in an area of approximately 40 km². The magnetic parameters measured were: initial magnetic susceptibility, anhysteretic remanent magnetization, saturation isothermal remanent magnetization and parameters associated with superparamagnetic particles. These measurements combined with the elemental concentration previously analyzed were successful in the separation of anthropogenic and natural sources using Factor Analysis as Receptor Model. Also, spatial correlation was found between the magnetic parameters and the petrochemical complex plume. This study shows that the application of magnetic parameters as particulate matter sources' tracers is useful to improve the source apportionment of biomonitoring researches.