Understanding the behavior and fate of PAHs in karst systems is crucial, as their distinctive geological features could facilitate rapid pollutant transport and complex source-sink dynamics. Previous studies have predominantly concentrated in PAHs transport at the sediment-water interface using fugacity theory, but these lack an integrated approach that couples multiple environmental factors to further quantify the source-sink transformation processes of PAHs. In this study, PAHs in sediment and water of a typical karst wetland were determined during both wet and dry seasons. Results suggested that average PAHs concentrations increased by 10.6 % in water and by 46.0 % in sediment from wet seasons to dry seasons. A significant difference was also observed between the two seasonal source apportionments, suggesting that transport processes of PAHs in multiphase media should be integrated with source estimates. Increased secondary release potential of PAHs (3 rings and 4 rings) at the sediment-water interface was captured in dry seasons by linear mixed effect models. PAHs transport was strongly affected by seasonal effects and the presence of labile organic carbon. From wet to dry seasons, PAHs in sediment shifted from acting a “sink” to “secondary source” as suggested by a Bayesian Gaussian regression and Bayesian network modeling. This study provides valuable insights into the source - sink dynamics processes of PAHs in a typical karst wetland.