Toxic effects of complex mixed organic compounds in aerosols on

Considering the complexity of organic components in aerosols, this study aimed to compare the toxic effects of mixed PAHs and the highly toxic benzo[a]pyrene on Skeletonema costatum (S. costatum). To achieve this, weakly polar organic compounds containing PAHs (TSP-PAHs) were extracted from winter aerosols collected in Qingdao, China. The study then assessed and compared the toxicity of TSP-PAHs (the exposure concentrations were set at 0.15 - 1 μg/L) and a single PAH (1 μg/L benzo[a]pyrene) on S. costatum. Results showed that both TSP-PAHs and benzo[a]pyrene inhibited S. costatum growth, with TSP-PAHs exhibiting a stronger dose-dependent inhibitory effect. On the fourth day, growth inhibition in TSP-PAHs groups ranged from 58.8% to 96%, while benzo[a]pyrene caused only 15% inhibition. This suggests that mixed PAHs impose greater toxicity than a single PAH, likely due to synergistic effects and oxidative stress mechanisms.