Near real-time PM1 chemical composition measurements at a French urban background and coastal site under industrial influence over more than a year: Temporal variability and assessment of sulfur-containing emissions

Near real-time measurements of submicron particulate matter (PM1) were carried out at an industrial and coastal site in Dunkirk (Northern France) over a 14-month period (July 2013–September 2014). This is surrounded by various plants (metallurgy, petrochemistry, food processing, power plant, etc.) characterized intense ship traffic (~700–800 per day along the English Channel) harbour surroundings. The non-refractory (NR) particles (organics, sulfate, nitrate, ammonium chloride) black carbon measured Aerosol Chemical Speciation Monitor (ACSM) Aethalometer, respectively. Concomitant monitoring CO2, SO2, meteorological parameters was also performed. Both seasonal (five seasons including two summers) spatial (four identified sectors emissions: marine, urban, industrial-urban industrial) variabilities investigated. We present descriptive analysis PM1 composition, whose ambient concentrations ranged from less than 1 ?g m?3 up to approximately 100 during few pollution events. Gaseous SO2 SO4 systematically observed high (up 310 48.2 m?3, respectively) when plumes reached site. conversion ratio (Sp) total (Stot) sulfur relatively constant 0.1 RH ranges 30 70% but reaches average value 0.3 (90–100%). reflects enhancement SO2-to-SO4 gas-particle processes resulting increase aerosol acidity as shown comparison between predicted NH4 concentrations. An impact vertical mixing on using turbulence (?w) parameter. Indeed, (Sp/Stot) found be reduced under conditions due dilution effects.