Sources and geographical origins of fine aerosols in Paris (France)

Abstract

Abstract. The present study aims at identifying and apportioning the major sources of fine aerosols in Paris (France) – the second largest megacity in Europe –, and determining their geographical origins. It is based on the daily chemical composition of PM2.5 characterised during one year at an urban background site of Paris (Bressi et al., 2013). Positive Matrix Factorization (EPA PMF3.0) was used to identify and apportion the sources of fine aerosols; bootstrapping was performed to determine the adequate number of PMF factors, and statistics (root mean square error, coefficient of determination, etc.) were examined to better model PM2.5 mass and chemical components. Potential Source Contribution Function (PSCF) and Conditional Probability Function (CPF) allowed the geographical origins of the sources to be assessed; special attention was paid to implement suitable weighting functions. Seven factors named ammonium sulfate (A.S.) rich factor, ammonium nitrate (A.N.) rich factor, heavy oil combustion, road traffic, biomass burning, marine aerosols and metals industry were identified; a detailed discussion of their chemical characteristics is reported. They respectively contribute 27, 24, 17, 14, 12, 6 and 1% of PM2.5 mass (14.7 μg m−3) on the annual average; their seasonal variability is discussed. The A.S. and A.N. rich factors have undergone north-eastward mid- or long-range transport from Continental Europe, heavy oil combustion mainly stems from northern France and the English Channel, whereas road traffic and biomass burning are primarily locally emitted. Therefore, on average more than half of PM2.5 mass measured in the city of Paris is due to mid- or long-range transport of secondary aerosols stemming from continental Europe, whereas local sources only contribute a quarter of the annual averaged mass. These results imply that fine aerosols abatement policies conducted at the local scale may not be sufficient to notably reduce PM2.5 levels at urban background sites in Paris, suggesting instead more coordinated strategies amongst neighbouring countries. Similar conclusions might be drawn in other continental urban background sites given the transboundary nature of PM2.5 pollution.

Sources of atmospheric aerosol from long-term measurements (5years) of chemical composition in Athens, Greece

“…This sea salt profile contains non-negligible concentrations of NO 3 − and SO 4 −2 , which are however not typical of sea-spray aerosols. Consequently, the sea profile seems to be enriched by anthropogenic compounds during their transport to the studied urban background site, in agreement with other reported sites Bressi et al, 2013). The estimated contribution of this source is 6% (Fig.…”

“…Biomass burning is identified through the presence of noticeable proportions of potassium (nss-K + ), POM, SO 4 −2 , NH 4 + and Cl − , while it is worth noting that there is no contribution from NO 3 − . This finding suggests that this biomass burning aerosol is freshly emitted near the studied site and has undergone no substantial atmospheric aging (Bressi et al, 2013). The contribution of this factor to the PM 2.5 mass is on average 7% (Fig.…”

Comparison of ionic and carbonaceous compositions of PM2.5 in 2009 and 2012 in Shanghai, China

“…The 75th percentiles of PM 2.5 and its carbonaceous components were selected, which meant that only the higher 25% of the samples were used for defining the potential source regions (Bressi et al, 2014;Waked et al, 2014). In order to reduce the effects of artifacts usually linked to the small numbers of endpoints, the PSCF values were multiplied by an arbitrary weight function W ij to better reflect the uncertainties in the values for these cells (Polissar et al, 1999).…”

Elucidating carbonaceous aerosol sources by the stable carbon δ13CTC ratio in size-segregated particles

“…Fine atmospheric particles (D p b 1.0 μm) have become a major public health concern (Kan et al, 2012;Lazaridis et al, 2002;Sheppard et al, 1999). Sea spray, dust, wildfires, secondary biogenic organic and secondary inorganic matter are the dominant aerosol types on a global scale (Bauer et al, 2004;Hoyle et al, 2011;Kaufman et al, 2002;Spracklen et al, 2009;Vignati et al, 2010;Voutsa et al, 2014), while in urban areas, one of the main primary sources of atmospheric PM is road traffic (Byčenkienė et al, 2014;Bressi et al, 2014;Cao et al, 2011;Huang et al, 2014;Wehner et al, 2002;Zhu et al, 2002), with diesel vehicles in particular being associated with higher emissions of fine and ultrafine particles. Numerous studies demonstrated that biomass burning, either of wildfire or domestic fuel origin, can be a significant contributor to the primary sources as well (Alves et al, 2011;McMeeking et al, 2009;Puxbaum et al, 2007;Ryu et al, 2007;Ulevicius et al, 2010).…”