Use of Chemical Signature to Trace the Impact of Emission Sources

Abstract

\n The composition of organic fraction associated to particulate emissions depends on their nature as well as on contour conditions. Therefore, many Authors have investigated the chemical signature of airborne particulate matter and dusts with the goal of identifying the pollution sources and assessing their impact on the environment and health. Usually, Authors use three complementary tools for this goal; they are specific source markers, concentration ratios of pairs of congeners, and percent distributions of homologues within a group. After the presentation of the state-of-the-art about non-polar aliphatic (alkanes and alkenes), aromatic (PAHs, Nitro-PAHs) and polar (fatty acids, organic halides, polysaccharides) compounds associated to emissions, this paper provides new information with regard to chemical signature non-polar fraction, suitable to trace the impact of sources on airborne particulate matter and settled dust. Non-polar organic fraction comprises short/medium-chain alkenes and alkanes (with carbon numbers ranging from 12 to 23), which display distinct relative abundances in petrol-derived exhausts, microorganism residues and high vegetation leaf debris. Meanwhile, long-chain alkanes associated to tobacco smoke show a peculiar iso/anteiso/normal homologues fingerprint as well as n-hentriacontane percentages higher than other emissions. Based on this particular alkane distribution, two indexes (ATSR and AICR) have tentatively identified and tested though comparing their rates in some sets of particulate samples. Until now, the study of molecular signature has overall limited to qualitative purposes and seldom exploited to achieve quantitative estimates of contributions of sources to air pollution. Future investigations will reach this goal through further clarifying the nature and behavior of organic contaminants associated to airborne and settled particulate matters.