Polycyclic aromatic compounds in soils from a petrochemical-contaminated site in eastern China: Target and non-target...

The contamination characteristics and risks associated with polycyclic aromatic contaminants (PACs) remain insufficiently understood. This study investigated co-occurrence patterns of 16 polycyclic aromatic hydrocarbons (PAHs) and 36 of their derivatives in soils collected from a petrochemical contaminated area in eastern China. The total concentration range of PAHs was 48.7-29,600 ng/g; while that for oxidized PAHs, nitrated PAHs, brominated PAHs, and chlorinated PAHs was 2.13-1940 ng/g, 58.0-801 ng/g, 1.99-462 ng/g; and 0.998-46.1 ng/g, respectively. Non-target screening using gas chromatography coupled with high-resolution mass spectrometry enabled the tentative identification of 82 PACs at varying confidence levels. Structural assignments were supported by relative retention indices and spectral matching, with 18 compounds further confirmed using reference standards. The semi-quantitative total concentration of these newly identified PACs was 0.500 ng/g-10,700 ng/g. Notably, 24 compounds, such as 13H-dibenzo[a,h]fluorene, and 9,10-dihydro-benzo(e)pyrene, were reported for the first time in the soil environment, highlighting the complexity of PAC contamination beyond conventionally measured PAHs. Additionally, screening-level ecological risk prioritization (prioritization index analysis) revealed that 16.4% of target and identified PACs posed potential risk to soil organisms, with 2-methylchrysene showing the highest risk priority. These findings significantly enhance the understanding of the environmental occurrence, diversity, and ecological risks of PACs and their derivatives in contaminated soils.