Size-segregated urban particulate matter: mass closure, chemical composition, and primary and secondary matter content.

Abstract

Forty-nine components of ambient particulate matter (PM) in size-fractionated PM were investigated at an urban background site in Katowice (Silesian Agglomeration in Southern Poland) in the non-heating season of 2012. PM was analyzed for two groups of carbon compounds (organic (OC) and elemental (EC) carbon, Lab OC-EC Aerosol Analyzer), five major water-soluble ions (NH4+, Cl−, SO42−, NO3−, and Na+ contents in PM water extracts, ion chromatography), 26 elements (X-ray fluorescence spectrometry), and 16 polycyclic aromatic hydrocarbons (PAHs, gas chromatography). The distributions of the masses of these components among 13 basic PM fractions were determined, and chemical mass closure was checked for each of these fractions separately. The particles having their aerodynamic diameters in the interval 0.03–0.26 μm, the fraction PM0.03–0.26, contributed about 13 % to the total PM mass. This PM fraction consisted of primary particles predominantly composed of various inorganic compounds, primary organic compounds, and, in lesser amounts, of elemental carbon, secondary ions, and secondary organic compounds. The second particle fraction, PM0.26–1.6, consisted mainly of secondary matter, and its mass contribution to the total PM mass was about 59 %. The third fraction, PM1.6–40, was a fraction of coarse particles composed of mineral/soil and organic matter and elemental carbon. It contributed to the PM mass about 28 %. For each of PM0.03–0.26, PM0.26–1.6, and PM1.6–40, the health hazard from its 16 PAH contents was determined by computing toxicity factors. PM0.26–1.6 posed the greatest health hazard from the mixture of the 16 PAHs that it contained, PM1.6–40 was the next, and the hazard from the PM0.03–0.26-bound 16 PAHs was the smallest. The molecular diagnostic ratios computed for these three fractions were specific for coal and wood combustion; some indicated the road traffic effects.