Fine particles at a background site in Central France: Chemical compositions, seasonal variations and pollution events.

To expand our knowledge of regional fine particles in Central France (Centre-Val de Loire region), a field observation study of PM2.5 was carried out at Verneuil site (46.81467N, 2.61012E, 180 m.a.s.l.) from 2011 to 2014. The mass concentrations of water-soluble inorganic ions (WSIIs), organic carbon (OC), elemental carbon (EC) and biomass burning tracer (Levoglucosan) in PM2.5 were measured. Annual average PM2.5 mass concentrations were 11.8, 9.5, 12.6 and 10.2 mu g.m(-3) in 2011, 2012, 2013 and 2014, respectively, three of four higher than the WHO guideline of 10 mu g.m(-3). Secondary inorganic aerosol (SIA) and organic matter (OM) appeared to be the major components in PM2.5 in Verneuil, contributing 30.1-41.8% and 36.9-46.3%, respectively. Main chemical species were observed in the following order: winter >= spring > autumn > summer. Backward atmospheric trajectories were performed using Hysplit model and suggested that the PM2.5 pollutants caused by atmospheric transport were mainly originated from European inland, mainly east to north-east areas. During the observation period, five pollution events were reported and indicated that not only the polluted air masses from central Europe but also the biomass burning from East Europe significantly influenced the air quality in Verneuil site. (C) 2017 Elsevier B.V. All rights reserved.