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Poster De Conférence Année : 2021

Speciation of the PM2.5 carbonaceous fraction in two urban industrial areas in the East Mediterranean

Résumé

Fine particulate matter has been shown to contribute to many environmental problems and might cause serious effects on the human health. The carbonaceous fraction contributes to a large fraction of PM and is divided into organic (OC) and elemental (EC) carbon. The former is a complex mixture of organic compounds that can be partitioned into primary (POC) and secondary (SOC) organic carbon while the latter is emitted by primary incomplete combustion processes. PM2.5 samples were collected for a year in two urban sites under industrial influence in Lebanon: Zouk Mikael region (ZK) and Fiaa region (FA). ZK is characterized by the biggest power plant in the country which runs on heavy fuel oil, a high density of population along with high number of diesel private generators and traffic. FA is surrounded by chemical industries such as the cement plants along with their corresponding quarries, and a sulfuric acid and phosphate fertilizer industry with less traffic than ZK and lower number of generators. OC and EC average mass concentrations in PM2.5 were 4.6 and 1.3 µg/m3 at ZK, and 1.3 and 0.5 µg/m3 at FA respectively, resulting in a OC/EC ratio of 4.0 at ZK and 7.3 at FA indicating a predominance of anthropogenic sources. The higher ratio observed at FA indicates higher secondary organic aerosols formation due to the surrounding forest lands. SOC was also estimated and contributes to 47% and 57% of total OC at ZK and FA, respectively. Within the organic fraction, n-alkanes and Polycyclic Aromatic Hydrocarbons (PAHs) are investigated. Similar concentrations were found for n-alkanes at both sites and are mainly emitted by anthropogenic activities as shown by the carbon preference index values close to unity and low wax percentages. The profiles shift to high molecular weight alkanes (>C26) during summer indicating a higher contribution of natural activities compared to winter. The sum of the 16 investigated PAHs at ZK is 2.56 ng/m3, three times higher than the one at FA (0.95 ng/m3) especially for indeno[1,2,3-c,d]pyrene linked to the presence of the power plant at ZK. A diagnostic ratio for indeno[1,2,3-c,d]pyrene/(indeno[1,2,3-c,d]pyrene + benzo[g,h,i] perylene) was proposed in the range of 0.8-1.0 for heavy fuel oil combustion from the power plant. Other diagnostic ratios for PAHs are also used to identify PAHs sources in both sites. The use of diagnostic tools is essential to identify emission sources in the areas. However, further investigations are needed such as source apportionment methods to quantify the contribution of the different sources as well as health risk assessment studies in order to highlight the effect of these compounds on human health.

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Dates et versions

hal-04407390 , version 1 (20-01-2024)

Identifiants

  • HAL Id : hal-04407390 , version 1

Citer

Marc Fadel, Frédéric Ledoux, Mariana Farhat, Adib Kfoury, Konstantina Oikonomou, et al.. Speciation of the PM2.5 carbonaceous fraction in two urban industrial areas in the East Mediterranean. European Aerosol Conference (EAC 2021), Aug 2021, Birmingham (Online), United Kingdom. ⟨hal-04407390⟩
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