Fine particles sampled at an urban background site and an industrialized coastal site in Northern France — Part 1: Seasonal variations and chemical characterization

Abstract

The chemical composition of particulate matter sampled at two French Northern sites (Douai, DO – urban background; Grande-Synthe, GS – industrialized coastal site) was investigated during two summer and winter field campaigns at each site. Measurements of the major chemical species (organic, sulfate, nitrate, ammonium, chloride) in the non-refractory submicron aerosols (NR-PM1) were carried out by a High Resolution Time-of-Flight Aerosol Mass Spectrometer. Black Carbon in PM2.5 was monitored using an Aethalometer, while the OC and EC fractions and some targeted chemical organic families (polycyclic aromatic hydrocarbons, PAHs; dicarboxylic acids, DCAs) were quantified by the simultaneous collection of PM2.5 on filters followed by offline analyses. The seasonal trends and winter-to-summer (W/S) concentration ratios are discussed in this paper. Results indicate that the total average mass concentrations of PM2.5 varied between 20.5μgm−3 and 32.6μgm−3 in DO and between 10.6μgm−3 and 29.9μgm−3 in GS during summer and winter, respectively. Similar concentration patterns were found for PAHs and Organic Carbon (OC, representing ~80% of the total carbon) with highest concentrations in winter at the urban site. DCA concentrations showed less seasonal variations, although the highest value also appeared during winter. Total NR-PM1 presented concentrations in summer lower by a factor of 4 (for DO) and 10 (for GS) than those observed in winter. Organics and nitrates dominated the NR-PM1 in DO for both seasons and during winter in GS while sulfates and nitrates were the most dominant species in summer in GS. Average chloride concentrations were slightly more important in GS than those in DO related to its use in industrial processes and no significant seasonal trend was observed. The size-resolved chemical composition showed that aerosols sampled in DO in winter are more aged than those collected in GS where fresh emissions of sulfate from the industrial sector were observed.