The importance of compound-specific radiocarbon analysis in source identification of polycyclic aromatic hydrocarbons: A critical review

As unavoidable by-products of the combustion of organic matter, the sources of carcinogenic polycyclic aromatic hydrocarbons (PAHs) are an area of great research interest in environmental monitoring, environmental forensics, and organic geochemistry. Molecular diagnostic ratios, receptor models, and stable isotope analysis are the most widely used methods to identify the sources of PAHs. However, some studies have demonstrated that these conventional methods have several disadvantages including overlapping end-members (or “non-uniqueness”), unexpected “blending,” secondary reaction and degradation, which lead to ambiguous PAH source results. At the end of the last century, compound-specific radiocarbon analysis (CSRA) focusing on the molecular level radiocarbon signatures was introduced for PAH source identification, because of its effectiveness in avoiding uncertainties of the conventional methods. CSRA has an excellent ability to distinguish the fractional contributions of fossil fuels and biomass burning. Here, by reviewing the merits and limitations of conventional methods, we point out that their unquestioning application needs to be criticized in PAH source identification, and further highlight the particular advantages of CSRA. Specifically, we summarize the application and prospects of CSRA in PAH source identification. We conclude that CSRA provides a powerful tool to accurately quantify the sources of aromatic pollutants, to reveal their sedimentary radiocarbon records, and to elucidate regional energy structure and fuel consumption. In doing so, we provide a critical resource to expand the application of CSRA in environmental science. To the best of our knowledge, this is the first comprehensive review of the application of CSRA for PAH source identification.