Abstract
This article presents the distribution of the dithiothreitol-based (DTT) redox activity of water-soluble airborne particulate matter (PM) from two urban sites in the city of Thessaloniki, northern Greece in four size ranges (<0.49, 0.49–0.97, 0.97–3.0 and >3 μm). Seasonal and spatial variations are examined. The correlations of the mass-normalized DTT activity with the content of PM in water-soluble organic carbon (WSOC) and non-water-soluble carbonaceous species, such as organic and elemental carbon, as well as with solvent-extractable trace organic compounds (polycyclic aromatic hydrocarbons and nitro-derivatives, polychlorinated biphenyls, organochlorines, polybrominated biphenyl ethers) and polar organic markers (dicarboxylic acids and levoglucosan), are investigated. Our study provides new and additional insights into the ambient size distribution of the DTT activity of the water-soluble fraction of airborne PM at urban sites and its associations with organic PM components.
Highlights
Exposure to particulate matter (PM) has been linked to adverse health effects such as respiratory and cardiovascular diseases and neurological disorders [1,2]
Water-soluble DTT activity was measured in size-segregated PM samples from an urban traffic (UT) and an urban background (UB) site during the cold and the warm season
Overall, excepting summertime particle fractions 3 μm, that exhibited higher DTT activity at the UT site, suggesting the dominant contribution of traffic-related emissions, in all other PM samples, DTT activity was higher at the UB site that is characterized by increased biomass burning
Summary
Exposure to particulate matter (PM) has been linked to adverse health effects such as respiratory and cardiovascular diseases and neurological disorders [1,2]. Effects were linked to PM10 or PM2.5 mass concentrations. Oxidative stress, resulting when the generation of reactive oxygen species (ROS), or free radicals, exceeds the available antioxidant defenses, has been suggested as an important underlying mechanism of action by which exposure to PM may lead to adverse health effects [5]. Oxidative potential of PM (i.e., the ability of particles to generate ROS), integrates various biologically relevant properties, including size, surface, and chemical composition; it may provide a more health-based exposure measure than PM mass alone and may be a better measure of the biologically effective dose that drives adverse health effects [6,7]. The electron transfer from DTT to oxygen is monitored by the rate at which DTT is consumed under a standardized set of conditions, and the rate is proportional to the concentration of the redox-active species in the PM sample [14,15]
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