Chemical composition and oxidative potential of atmospheric particles heavily impacted by residential wood burning in the alpine region of northern Italy

The main objective of this study was to estimate the contribution of emissions from wood burning (WB) combustion to particulate matter (PM10) oxidative potential (OP) in relation to its chemical composition. A sampling campaign was carried out at an Alpine rural site during winter 2016–2017, when wood is largely used as fuel for domestic heating and therefore WB is a prevalent PM emission source. PM10 samples were analyzed for their chemical constituents, including metals and trace elements, water soluble total carbon (WSTC), sugars, and Polycyclic Aromatic Hydrocarbons (PAHs), with specific concern to anhydrosugars, K+ and Rb, as markers of WB. The OP was measured by the dithiothreitol (DTT) and ascorbic acid (AA) acellular assays and the volume normalized responses were investigated, OPDTTV and OPAAV, respectively. On average, the two assays measured similar values, even though the mean OPDTTV response was significantly higher than OPAAV, i.e., 0.33 ± 0.07 nmol min−1 m−3 and 0.28 ± 0.08 nmol min−1 m−3, respectively. To identify the species mostly contributing to the PM10 OP, a series of statistical analyses was performed, namely Pearson correlation analysis, multiple linear regression, hierarchical cluster and partial least squares regression analyses. Results from this study indicated that the PM10 redox activity was strongly correlated with the characteristic components of WB emissions, namely WSTCnet, the net water-soluble carbonaceous component, total concentrations of anhydrosugars (Σanhydr) and of Polycyclic Aromatic Hydrocarbons (ΣPAHs).