Source apportionment of PM2.5 oxidative potential in an East Mediterranean site

Marc Fadel; Dominique Courcot; Gilles Delmaire; Gilles Roussel; Charbel Afif; Frédéric Ledoux

doi:10.1016/j.scitotenv.2023.165843

Source apportionment of PM_2.5 oxidative potential in an East Mediterranean site

Sci Total Environ. 2023 Nov 20:900:165843. doi: 10.1016/j.scitotenv.2023.165843. Epub 2023 Jul 27.

Authors

Marc Fadel¹, Dominique Courcot², Gilles Delmaire³, Gilles Roussel³, Charbel Afif⁴, Frédéric Ledoux⁵

Affiliations

¹ Emissions, Measurements, and Modeling of the Atmosphere (EMMA) Laboratory, CAR, Faculty of Sciences, Saint Joseph University, Beirut, Lebanon; Unité de Chimie Environnementale et Interactions sur le Vivant, UCEIV UR4492, Université du Littoral Côte d'Opale (ULCO), Dunkerque, France.
² Unité de Chimie Environnementale et Interactions sur le Vivant, UCEIV UR4492, Université du Littoral Côte d'Opale (ULCO), Dunkerque, France.
³ Laboratoire d'Informatique Signal et Image de la Côte d'Opale (LISIC), Université du Littoral Côte d'Opale, F-62228, Calais, France.
⁴ Emissions, Measurements, and Modeling of the Atmosphere (EMMA) Laboratory, CAR, Faculty of Sciences, Saint Joseph University, Beirut, Lebanon; Climate and Atmosphere Research Center, The Cyprus Institute, Nicosia, Cyprus.
⁵ Unité de Chimie Environnementale et Interactions sur le Vivant, UCEIV UR4492, Université du Littoral Côte d'Opale (ULCO), Dunkerque, France. Electronic address: frederic.ledoux@univ-littoral.fr.

PMID: 37516168
DOI: 10.1016/j.scitotenv.2023.165843

Abstract

This study aimed to evaluate the oxidative potential (OP) of PM_2.5 collected for almost a year in an urban area of the East Mediterranean. Two acellular assays, based on ascorbic acid (AA) and dithiothreitol (DTT) depletion, were used to measure the OP. The results showed that the mean volume normalized OP-AA_v value was 0.64 ± 0.29 nmol·min^-1·m^-3 and the mean OP-DTT_v was 0.49 ± 0.26 nmol·min^-1·m^-3. Several approaches were adopted in this work to study the relationship between the species in PM_2.5 (carbonaceous matter, water-soluble ions, major and trace elements, and organic compounds) or their sources and OP values. Spearman correlations revealed strong correlations of OP-AA_v with carbonaceous subfractions as well as organic compounds while OP-DTT_v seemed to be more correlated with elements emitted from different anthropogenic activities. Furthermore, a multiple linear regression method was used to estimate the contribution of PM_2.5 sources, determined by a source-receptor model (Positive Matrix Factorization), to the OP values. The results showed that the sources that highly contribute to the PM_2.5 mass (crustal dust and ammonium sulfate) were not the major sources contributing to the values of OP. Instead, 69 % of OP-AA_v and 62 % of OP-DTT_v values were explained by three local anthropogenic sources: Heavy Fuel Oil (HFO) combustion from a power plant, biomass burning, and road traffic emissions. As for the seasonal variations, higher OP-AA_v values were observed during winter compared to summer, while OP-DTT_v did not show any significant differences between the two seasons. The contribution of biomass burning during winter was 33 and 34 times higher compared to summer for OP-AA_v and OP-DTT_v, respectively. On the other hand, higher contributions were observed for HFO combustion during summer.

Keywords: Correlation analysis with chemical composition; Multiple linear regression; PM oxidative potential; Seasonal variations; Source apportionment.