Optical Properties, Chemical Composition and the Toxicological Potential of Urban Particulate Matter

This paper discusses the diurnal variation and the interdependences between the physical, chemical and toxicological characteristics of atmospheric carbonaceous particulate matter (CPM) and co-emitted gaseous components. Measurements were carried out at two different urban sites during a 2-month period. On-line measured parameters were optical absorption coefficients (OAC), total number concentration (TNC), mass concentration of CPM and the concentration of gaseous species (CO, NOx and BTEX). Off-line analyses were carried out on filters collected with 6-hour time resolution. The concentrations of elemental carbon (EC), organic carbon (OC), total carbon (TC), levoglucosan (LG) and polycyclic aromatic hydrocarbons (PAH) were determined. The ecotoxicity of CPM was assessed by the Vibrio Fischeri marine bioluminescence inhibition bioassay (ISO 21338: 2010). We found (r > 0.498) positive and wavelength dependent correlation between the CPM related parameters based on optical response (OAC, AAE) and thermal stability (TC, EC, OC, OC/ TC). We also revealed weak (r = 0.309) or moderate (r = 0.448) correlation between the AAE and the ecotoxicity data indicating that carbonaceous fraction of the ambient particulate matter has ecotoxicological impact. Based on the determined correlations, we propose the applicability of the AAE determined by multi wavelength photoacoustic measurements as a possible candidate for first-screening the toxicological impact of optically active carbonaceous ambient particulate matter. The strengths and the limitations of this methodology are both discussed here.