Source identification of PAHs in soils based on stable carbon isotopic signatures

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the environment and some exhibit carcinogenic and mutagenic toxicity. Three methods have been used for identification of PAHs sources in soils, including molecular diagnostic ratios, receptor models, and stable C isotopic signatures, with stable C isotopic ratios based on delta C-13 values being underutilized. Isotopic fractionation effects occur after environmental transportation of PAHs such as deposition and burial. This characteristic makes this method useful in source identification. Here, we provided a comprehensive review of tracing sources of soil PAHs using stable C isotopic fingerprinting technique. Fractionation of C isotopes occurs during formation and degradation processes of PAHs, making them useful tools to trace sources of PAHs in soils. The fundamentals of delta C-13 measurement and compound-specific isotopic analysis to trace sources of soil PAHs are summarized. Furthermore, for the first time, the biogeochemical cycle and contamination source evaluation based on delta C-13 signatures for soil PAHs are proposed. In addition, radioactive C isotope and stable H isotope ratios of PAHs are also briefly introduced as supplementary techniques. In short, these methods offer much promise, but still need work to fill in knowledge gaps. Establishing a C isotopic signature database to expand the utilization of this technique for tracing PAHs in soils is needed.