Congener-specific distribution of dioxin-like compounds and their potential source-related influences in coniferous needles and deciduous leaves across South Korea.

In this study, the levels and congener profiles of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), and polychlorinated naphthalenes (PCNs) were assessed in coniferous needles and deciduous leaves across South Korea, and their potential source-related influences were examined, using specimens archived in the National Environmental Specimen Bank. The mean concentrations of Σ17 PCDD/Fs, Σ30 PCBs, and Σ42 PCNs were significantly higher in coniferous needles (3.72, 408, and 73.9 pg/g dw, respectively) than in deciduous leaves (0.34, 120, and 6.71 pg/g dw, respectively). Toxic equivalents (TEQs) were markedly higher in coniferous needles than in deciduous leaves, with PCDD/Fs dominating the TEQ in coniferous needles and dl-PCBs in deciduous leaves, reflecting differences in detection frequency, seasonal exposure time, and compound-specific partitioning behavior. Dominant congeners included OCDD among PCDD/Fs, CB-118 among PCBs, and CN-73 among PCNs. Lipid content showed strong positive correlations with all pollutant groups, indicating lipid-driven accumulation in leaves, although lipid normalization revealed compound-specific differences in partitioning behavior. The observed source-related patterns were consistent with influences from industrial combustion and diffuse atmospheric inputs. Comparison with atmospheric data showed consistent spatial distributions and congener profiles, indicating that foliar burdens reflect regional airborne contamination. These findings indicate that contamination levels in South Korea are comparable to those reported for moderately industrialized regions worldwide and underscore the utility of vegetation as a cost-effective tool for long-term monitoring of airborne POPs.