Intercomparison of source apportionment approaches within the EU‐MED APICE project

The EU-MED APICE project (Common Mediterranean strategy and local practical Actions for the mitigation of Port, Industries and Cities Emissions; www.apiceproject.eu) aims to quantify the impact of harbour and harbour related activities to PM concentration observed in 5 Mediterranean harbours: Barcelona (Spain), Marseille (France), Genoa (Italy), Venice (Italy) and Thessaloniki (Greece). For that purpose, long term monitoring campaigns are currently underway in these 5 harbours by each of the local scientific partner of the project. In order to intercompare source apportionment approaches used by each partner and to harmonize the methodologies between areas under study, a 6 weeks intercomparison campaign has been conducted in Marseille during winter 2011. Marseille is the most important harbour of the Mediterranean Sea. It handles twice the traffic compared to Genoa, and nearly three times the traffic of Barcelona or Valencia. A huge petrochemical area, among other industrial plants (steel mill, coke plant...), is also located close to Marseille, the second most populated city in France with more than 1 million inhabitants. Industrial and shipping emissions of PM are generally among the least well known sources in the field of atmospheric research and largely merit in depth studies in this context. Furthermore, this intercomparison campaign is also the ideal framework to test our ability to apportion such specific sources among many others in a densely populated area. Comprehensive chemical characterization of PM2.5 and PM10 have been performed by each partner on the same 24h basis during this 6 week-long campaign, including measurements of major ions, OC/EC, metals/elements and organic markers (hopanes, levoglucosan, PAHs, n-alkanes, fatty acids, resin acids, methoxy phenol,..). Independent results from each partner are now intercompared. High temporal resolution measurements were also achieved with high-resolution time-of-flight aerosol mass spectrometers (HR-ToFAMS), aethalometer, multi-angle absorption photometer ( AAP), scanning mobility particle sizer (SMPS) and proton transfer reaction mass spectrometer (PTR-MS) for VOC measurements. Positive Matrix Factorization (PMF) and Chemical Mass Balance (CMB) were used to apportion sources. Preliminary example of source apportionment is presented with figure 1. In this presentation, we will compare several source apportionment approaches: - CMB with organics markers and elements/metals, - PMF with elements/metals and major aerosol fractions (OC/EC, major ons), - PMF with elements/metals, organic markers and major aerosol fractions (OC/EC, major ions) (figure 1), - AMS/PMF. Combination of CMB and PMF has also been performed (i.e. factors derived from PMF analysis have been injected as source profiles in CMB calculation). This combined approach is particularly interesting for sources such as mineral or road dust, for which no source profile exists or presents too much variability between environments to be considered as scientifically sounded).