On the influence of VOCs on new particle growth in a Continental-Mediterranean region

Abstract

A field campaign has been performed in the Madrid region to study the VOC influence in the growth of new particles in ambient air. A number of instruments have been deployed to characterize the main pollutant gases and particle properties and composition. The measurements were performed simultaneously at three sites (rural, urban background and urban traffic influenced) in the period 1–17 July 2019. The sites: Tres Cantos (rural), CIEMAT (urban background) and Leganés (urban traffic) were located within the Madrid airshed. Particle size distributions, mass concentrations at fractions PM10, PM2.5 and PM1, black carbon, VOCs species and gaseous pollutants (NOx and O3) were obtained in the sites. Some supplementary measurements were obtained in at least one of the sites: meteorological parameters, non-refractory submicron aerosol species and vertical profiles of aerosol optical properties. It has been observed that the new particle formation (NPF) events, nucleation and subsequent growth, happened at a regional scale, although differently among the sites. In the rural site, fewer events than expected were observed because of the high temperatures that affected the BVOC emissions. In the urban background site, the highest number of events was reached. In this station, it is common to receive air masses from the nearby forest and from the urban area, producing a mix of conditions with high BVOC and AVOC concentrations. In the urban traffic site, several NPF cases appeared, being a site dominated by AVOCs. Among the BVOCs measured in the three stations, the most common were α-Pinene and Limonene. Among the AVOCs measured, aromatics and linear hydrocarbon compounds for C10 and above were found. The linear group was found to be predominant during the NPF event days in the urban background site. This work provides new insights about the aerosol-forming precursors and growth of new particles in the Madrid region.