Using the C-13/C-12 carbon isotope ratio to characterise the emission sources of airborne particulate matter: a review of literature

Particulate matter (PM) from atmospheric aerosols contains carbons that are harmful for living organisms and the environment. PM can originate from vehicle emissions, wearing of vehicle components, and dust. Size and composition determine PM transport and penetration depth into the respiratory system. Understanding PM emission characteristics is essential for developing strategies to improve air quality. The number of studies on carbon isotope composition (C-13/C-12) of PM samples to characterise emission factors has increased. The goal of this review is to integrate and interpret the findings from C-13/C-12 carbon isotope ratio (delta C-13, parts per thousand) analyses for the most common types of emission sources. The review integrates data from 25 studies in 13 countries. The range of delta C-13 of PM from vehicle emissions was from -28.3 to -24.5 parts per thousand and for non-vehicle anthropogenic emissions from -27.4 to -23.3 parts per thousand. In contrast, PM ranges for delta C-13 from biomass burning sources differed markedly. For C-3 plants, delta C-13 ranged from -34.7 to -25.4 parts per thousand and for C-4 plants from -22.2 to -13.0 parts per thousand. The C-13/C-12 isotope analysis of PM is valuable for understanding the sources of pollutants and distinguishing vehicle emissions from biomass burning. However, additional markers are needed to further distinguish other anthropogenic sources.