Spatial and seasonal variability of the contribution of sources to PM2.5, PM10 and their oxidative potential in different sites in a central Mediterranean area

Oxidative potential (OP) is a potential indicator of negative health effects of particulate matter (PM). To address mitigation strategies, there is need of understanding how natural and anthropogenic sources influence OP at different sites. This work investigates spatial and seasonal variabilities of PM_2.5 and PM₁₀ concentrations, composition, and oxidative potential (OP^DTT_V, obtained with DTT assay), simultaneously at 22 sites in a central Mediterranean area in south Italy. Source apportionment using PMF5 allowed to evaluate the contributions of eight sources: traffic, biomass burning (BB), nitrate, sulphate-rich, marine, crustal, carbonates/construction, and industrial (only for PM_2.5). Nitrate, traffic, and BB had larger contributions during the cold season and presented spatial variability with exclusion of nitrate. Industrial contributions did not have relevant seasonal or spatial variability. The other sources had an opposite trend with larger values during the warm season but only sulphate-rich had non-negligible spatial variability. OP^DTT_V had relevant spatial variability only during the cold season. Four sources had statistically significant contributions to OP^DTT_V: traffic, BB, sulphate-rich, and crustal (in descending order). The use of soluble and insoluble fractions of OC and Ca in PMF5 allowed a better separation between traffic and BB sources and allowed to determine the role of local construction works. The results may have implications in future policies for mitigation strategies of OP targeting specific sources categories.