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

Daniele Contini,Eva Merico,Stefano Decesari,Franco Belosi,Francesco Manarini,Fabio Massimo Grasso,Francesca Volpi,Paola De Nuntiis,Matteo Rinaldi,Andrea Gambaro,Daniela Cesari,Elisa Morabito

doi:10.3390/atmos10120758

Abstract

Some studies suggested a role of the atmospheric particulate matter (PM) and of its oxidative potential (OP) in determining adverse health effects. Several works have focused on characterisation of source contributions to PM OP, mainly using three approaches: correlation between OP and chemical markers 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 receptor models. Up to now, comparison of results obtained with different approaches on the same dataset is scarce. This work aims to perform a OP study of PM2.5 collected in an industrial site, located near a biogas production and combustion plant (in southern Italy), comparing different approaches to investigate the contributions of the different sources to OP. The PM2.5 samples were analysed for determining ions, metals, carbonaceous components, and OP activity with the DTT (dithiotreitol) assay. Results showed that OP normalised in volume (DTTV) is correlated with carbonaceous components and some ions (NO3−, and Ca2+) indicating that PM of combustion, secondary, and crustal origin could contribute to the OP activity. The source apportionment, done with the Environmental Protection Agency (EPA)—Positive Matrix Factorization (PMF5.0) model, identified six sources: secondary sulphate; biomass burning; industrial emissions; crustal; vehicle traffic and secondary nitrate; and sea spray. A MLR analysis between the source’s daily contributions and the daily DTTV values showed a reasonable agreement of the two approaches (PMF and MLR), identifying the biomass burning and the vehicle traffic and secondary nitrate as the main sources contributing to DTTV activity.

Highlights

Several studies worldwide have identified particulate matter (PM), and especially its fine fraction, as a critical parameter responsible for adverse health effects [1,2,3]
This work aims to perform a study of OP of the water-soluble fraction of PM2.5 collected at an industrial site located near a biogas plant in the background area of Sarno territory (Campania region, South of Italy) and to estimate the contribution of PM2.5 sources to the measured oxidative potential
The constraint was applied to the “vehicular traffic and secondary nitrate” profile, setting the ratio: organic carbon (OC)/elemental carbon (EC) = 2.3, obtained as the average value of the OC/EC ratios calculated on the traffic profiles present in the European database SPECIEUROPE DATABASE

Summary

Introduction

Several studies worldwide have identified particulate matter (PM), and especially its fine fraction, as a critical parameter responsible for adverse health effects [1,2,3]. Atmosphere 2019, 10, 758 oxidative potential (OP) of particulate matter, which leads to high concentrations of reactive oxygen species (ROS), chemical species capable of causing damage at the cellular level. These ROS trigger an oxidative stress response involving several proinflammatory cascades that result in pathology [6,7]. For this reason, in the international scientific community, the OP of atmospheric particulate has started to be considered as a general indicator of risks for human health due to atmospheric particulate matter [8]. Several studies were focused to develop/apply biological and chemical assays to quantify the oxidative potential of atmospheric aerosol and cellular oxidative stress response [9] leading to a variety of cellular [10,11] and acellular methods to evaluate OP

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Results

Conclusion