Fine particles sampled at an urban background site and an industrialized coastal site in Northern France—Part 2: Comparison of offline and online analyses for carbonaceous aerosols

<p>Particulate matter was sampled in Northern France during two summer and winter periods at both an urban background site (Douai, DO) and an industrialized coastal site (Grande-Synthe, GS). Ambient levels of particulate carbonaceous species and Polycyclic Aromatic Hydrocarbons (PAH) were measured by real-time measurements and via collection and analysis of offline filters (F). The comparison between online organic matter (OM) measured by an Aerosol Mass Spectrometer (AMS) and organic carbon (OC) determined by an offline thermal-optical method showed good linear trends in wintertime GS (<i>r</i><sup>2</sup> = 0.82 while only 0.50 in summer), and DO (<i>r</i><sup>2</sup> = 0.86 in summer and 0.92 in winter). However, significant differences were observed between analytical methods and sites with OC<sub>AMS</sub>/OC<sub>F</sub> ratios decreasing from 0.80 in DO during winter to ≈0.20 for GS in summer, suggesting that a large part of OM could be in the PM<sub>1</sub>–PM<sub>2.5</sub> fraction. The simultaneous measurements of Black Carbon (BC) and Elemental Carbon (EC) concentrations in PM<sub>2.5</sub> were also well correlated at both sites with <i>r</i><sup>2</sup> = 0.61–0.97 and slopes between 0.6 and 0.8. PAHs were analyzed in PM<sub>2.5</sub> and also measured online by AMS in PM<sub>1</sub>. Their wintertime concentrations were highly correlated in DO (<i>r</i><sup>2</sup> = 0.98) and to a lesser degree in GS (<i>r</i><sup>2</sup> = 0.67). <i>r</i><sup>2</sup> values determined for comparison between online and offline parameters (OC and PAHs) in GS were lower than in DO, probably due to a more complex aerosol composition and a higher variability of the physical and chemical properties resulting from the coastal situation and diversity of emission sources in the vicinity of GS.</p> <p>Copyright © 2017 American Association for Aerosol Research</p>