Preliminary insights into the chemical composition and emissions of urban VOCs in the East Mediterranean
Abstract
The Mediterranean region is an area where polluted air masses coming from Eastern and Central Europe increase air pollution, particularly during stagnation periods, together with intense solar radiation. It was demonstrated that the eastern coast of the Mediterranean Sea suffers from this kind of phenomena. Favorable weather conditions, remote sources, high urban and biogenic emissions lead to the formation of secondary pollutants (ozone and secondary organic aerosols, SOA), which may have significant impacts on health and climate. However, data are sparse in this region. The ECOCEM (Emission and Chemistry of Organic Carbon in the East Mediterranean - Beirut) project aims to improve our understanding of air pollution in this area by studying the composition of the gaseous and particulate phases in Beirut (Lebanon). Beirut is located on the eastern border of the Mediterranean basin. The goal of the project, which is taking place over two intensive field campaigns (July 2011 and February 2012), is to provide valuable observations on the composition and the temporal evolution of organics (summer versus winter),to identify and quantify the relative importance of sources of volatile organic compounds (VOCs) and aerosols (SOA) and to study the role of VOCs in the first oxidation steps of SOA formation. For that purpose, a large suite of primary and secondary VOCs (>60) were measured during the summertime campaign (July 2nd to July 17th 2011) at one suburban site in Beirut. Techniques encompass off-line sampling on carbonaceous sorbent tubes (2-hour time resolution) and liquid coil scrubbing (1-hour time resolution), an on-line GCFID (1-hour time resolution) and a PTR-MS (4-min time resolution). We will discuss here the atmospheric composition of VOCs in relation with their emissions. In particular, these data provide useful constraints to evaluate the first temporally and spatially resolved national emission inventory that was built for the year 2010. Preliminary results show that the summer mixing ratios of anthropogenic VOCs (aromatics and light alkanes) and secondary VOCs (acetaldehyde) mixing ratios could be 2 to 4 times higher than northern latitude megacities (Paris and Los Angeles). While traffic seems to control the diurnal variability of primary VOCs, other significant sources are suspected to contribute to aromatics and light alkane levels.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2011
- Bibcode:
- 2011AGUFM.A41B0066S
- Keywords:
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- 0345 ATMOSPHERIC COMPOSITION AND STRUCTURE / Pollution: urban and regional;
- 0365 ATMOSPHERIC COMPOSITION AND STRUCTURE / Troposphere: composition and chemistry