Source Apportionment of PM2.5 and of its Oxidative Potential in an Industrial Suburban Site in South Italy

Some studies suggested a role of the atmospheric particulate matter (PM) and of its oxidativepotential (OP) in determining adverse health effects. Several works have focused on characterisation ofsource contributions to PM OP, mainly using three approaches: correlation between OP and chemicalmarkers of specific sources; use of OP as input variable in source apportionment with receptor models;and multi-linear regression (MLR) between OP and source contributions to PM obtained from receptormodels. Up to now, comparison of results obtained with different approaches on the same dataset isscarce. This work aims to perform a OP study of PM2.5 collected in an industrial site, located neara biogas production and combustion plant (in southern Italy), comparing different approaches toinvestigate the contributions of the different sources to OP. The PM2.5 samples were analysed fordetermining ions, metals, carbonaceous components, and OP activity with the DTT (dithiotreitol) assay.Results showed that OP normalised in volume (DTTV) is correlated with carbonaceous componentsand some ions (NO3-, and Ca2+) indicating that PM of combustion, secondary, and crustal origin couldcontribute to the OP activity. The source apportionment, done with the Environmental ProtectionAgency (EPA)--Positive Matrix Factorization (PMF5.0) model, identified six sources: secondarysulphate; biomass burning; industrial emissions; crustal; vehicle traffic and secondary nitrate; and seaspray. A MLR analysis between the source's daily contributions and the daily DTTV values showed areasonable agreement of the two approaches (PMF and MLR), identifying the biomass burning andthe vehicle traffic and secondary nitrate as the main sources contributing to DTTV activity