First investigation into occurrence, trophodynamics, and risk implication of polychlorinated naphthalenes and polychlorinated biphenyls in a terrestrial food chain from Tibetan Plateau.

Research on the trophic transfer of Polychlorinated Naphthalenes (PCNs) and Polychlorinated Biphenyls (PCBs) in terrestrial organisms remains preliminary. Due to their structural similarities, it is hypothesized that PCNs and PCBs exhibit comparable trophic transfer behaviors. This study investigated the occurrence and trophic transfer of PCBs and PCNs in a terrestrial food chain (plant-plateau pika-eagle) from the interior Tibetan Plateau. PCB and PCN concentrations ranged from 9.92 to 114 ng/g lipid weight (lw) and 4.93 to 37.3 ng/g lw, respectively. Notably, distinct trophic transfer behaviors were found, with trophic magnification of ∑PCB \[trophic magnification factors (TMF) = 1.95\] and trophic dilution of ∑PCN TMF = 0.363. Unlike most PCN congeners, CN-54, CN-52/60, and CN-66/67 displayed biomagnification potential, and theoretical calculation revealed that quantum electronic effects in their structure played important roles. A model indicated that biotransformation half-life (HL) predominantly influenced trophic transfer in this terrestrial food chain. The maximum estimated toxic equivalent (TEQ) of PCBs in eagles exceeded the toxic reference values for Chinese avian species, while PCN TEQ remained relatively low. This is the first comprehensive investigation on trophic transfer of PCBs and PCNs in the Tibetan Plateau terrestrial ecosystem, highlighting the ecological risks and providing a basis for future research.