A multivariate approach to polycyclic aromatic hydrocarbon source apportionment in Connecticut, USA using compound-specific isotopic compositions

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants of concern due to their mutagenic/carcinogenic properties—identifying the source and transport of these compounds in the environment poses a significant challenge. Molecular distributions and stable isotopic compositions of PAHs vary as a function of both source and production/degradation processes, providing an opportunity to delineate origin and transport through the environment. This study utilizes a multivariate approach to examine spatial variations in PAH distributions and isotopic compositions (δ¹³C and δD) among soils and sediments in Connecticut, USA. Data show that, despite large variations in industrial activity and land use history as well as total PAH abundance within sediment sample, the distribution of PAHs is relatively consistent across sites—on average, 9.2% 2–3 ring, 48.1% 4 ring, 33.7% 5 ring, and 9.0% 6 ring compounds. This distribution indicates a mixture of sources primarily produced by pyrogenesis. Marine samples plot in a unique dual diagnostic ratio space of the PAHs, indicating a different source of combustion materials for maritime industry. In addition, they exhibit significantly lower proportions of low molecular weight PAHs due to solubility effects and remobilization. Fluvial samples mimic terrestrial signals, suggesting predominant sources of airborne deposition and terrestrial runoff. Compound-specific δ¹³C and δD are highly variable, ranging from −27.4 to −20.6‰ and −132 to −33‰, respectively. Based on established endmember isotopic compositions, PAHs collected from Connecticut reflect a mixture of three main sources: liquid fossil fuel combustion, low temperature coal combustion, and high temperature industrial processes.