Composition of torched crude oil organic particulate emitted by refinery and its similarity to atmospheric aerosol in the surrounding area

The absolute contents and relative distributions of organic aerosols [n-alkanes, n-alkanoic and n-alkenoic acids, nalkan- 2-ones and polycyclic aromatic hydrocarbons (PAH)] were determined in torched gases emitted during the crude oil extraction and in the free atmosphere of the Hassi-Messaoud city (Algeria). Monocarboxylic acids, both saturated and monounsaturated (from 9802to 20 057 ng m3), accounted for the major fraction of the total particulate organic matter identified both in torch exhaust and atmospheric particulate. n-Alkanes were also abundant both in the direct emission (from 460 to 632ng m3) and city atmosphere (462ng m3) and displayed a peculiar fingerprint characterised by the presence of a set of branched congeners around even carbon-numbered homologues and a strong even-to-odd predominance along the whole carbon number range (C16-C34). Whilst n-alkan-2-ones were absent in the city and poor in smokes emitted from the torches (from 31 to 42ng m3), PAH were present at low extents in all sites (from 18 to 65 ng m3). The incomplete thermal combustion of torched crude oil was very likely the main source of these particle- bound organic constituents in the city and its surrounding region.