AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Aerosol Interactions with Fog in Urban and Suburban Sites in Northeastern France: Applications of Carbon Isotopic Analysis
DENISE NAPOLITANO, Olivier Delhomme, Maurice Millet, Pierre Herckes, Arizona State University
Abstract Number: 129 Working Group: There Must be Something in the Water: Cloud, Fog and Aerosol Aqueous Chemistry for Aerosol Production
Abstract The Grand Est region of France experiences autumnal radiation fog that plays an important role in local atmospheric chemistry and the formation of secondary organic aerosol material. Fog and particulate matter studies have been conducted in this region, but the study of the effect of fog on the concentration and composition of particulate matter through tandem sampling of these phases has yet to be deeply explored. Moreover, the analysis of temporal changes in the stable carbon isotopic composition (δ13C) of these phases could provide information on the sources, droplet activation, and reactivity of carbonaceous particulate matter. Samples of fog and particulate matter were collected in the city of Strasbourg and the nearby suburb of Geispolsheim in the fall of 2016 and were characterized for their stable carbon isotopic compositions. In the presence of fog, the stable carbon isotopic composition of aerosols was depleted by up to 0.7‰ in PM2.5 in Strasbourg and up to 1.1‰ in PM10 collected in Geispolsheim. This type of isotopic depletion may be due to source-specific particle activation in which larger particles originating primarily from biogenic sources are preferentially scavenged as condensation nuclei relative to smaller, anthropogenically-derived particles. Additionally, the carbon isotopic composition of fog samples collected in Geispolsheim were enriched relative to interstitial particles by up to 1.7‰. This enrichment may also be attributed to the preferential activation of larger biogenic particles during fog formation, leaving smaller anthropogenic particles in the solid phase. Fog samples were also collected during this season in the neighboring suburb of Erstein. In both Geispolsheim and Erstein, fog samples were enriched in δ13C compared to fog collected in Strasbourg by up to 1.2‰, which may be due to the presence of a higher fraction of biogenic emissions relative to anthropogenic emissions in these areas. Similarly, in 2015, the stable carbon isotopic composition of fog samples collected in Geispolsheim was enriched by an average of 0.6‰ relative to those collected in the city of Metz. This study highlights the potential application of stable carbon isotopic analysis in studying dynamic multi-phase aerosol production processes.