Instrument package development for urban aerosol fast chemical measurements : study of Paris and Beijing aerosols.

The continuous population growth in urban area is accompanied by an increasing number of megacities especially in South East Asia. These urban regions form intense pollution spots with a particular concern for atmospheric particles. To evaluate their impact on climate, environment or human health, studies to document main sources and fast transformations of pollutants are mandatory. This may be obtained by quasi real time measurements of chemical composition. In this context, the present work shows the development and the qualification of a field instrumental package that has been built to retrieve aerosol chemistry on short duration scales. The package is composed of a PILS-IC (Particle-Into-Liquid-Sampler) for ion measurement, a thermo-optical analyser for EC and OC (EC-OC Sunset Field Analyzer), a PILS-TOC for water soluble OC measurements and a TEOM-FDMS for artefact free mass measurement. Optimisation and qualification of the instrument package are presented, followed by an evaluation of its potential using results of two field campaigns Paris (June 2007) and Beijing (August 2007) conducted at two different stages of its development. This package now allows PM2.5 mass and optical reconstructions on one-hour basis and provides data able to help for source identification (local vs regional, primary vs secondary) and a better understanding of organic aerosol properties (water solubility).