Polycyclic aromatic compounds (PACs) pose a significant threat to human health and ecological security. Despite the cross-media transport of PACs is a key phenomenon regulating their environment distribution and fate, its mechanism remains poorly understood. This study combined field observations with gas chromatography tandem high-resolution mass spectrometry, owing to its high sensitivity and selectivity for the determination of PACs in complex environmental samples, to investigate their concentrations and cross-media transport. Results show that the distribution of PACs in the environment is constrained by their molecular weight, with 2-3 ring PACs being more likely to exist in the gas phase and dissolved phase. Besides, terrestrial transport, upwelling and ocean fronts associated with seasonal ocean currents jointly regulate the spatial distribution of PACs in the atmosphere, seawater, and sediment. Low molecular weight (LMW) PACs and alkylated PACs have a high tendency to volatilize from seawater to atmosphere due to their high Henry's law constants. High wind speed promotes PACs volatilization while biodegradation, biological pumps and particle sedimentation promote the transport of PACs from the atmosphere to seawater and sediment. Sediments may not be the final sink for PACs, and pore water in sediment can serve as a dynamic source of PACs in seawater. On the global scale, the cross-media transport of PACs is regulated by the latitude distribution of environmental variables, presenting an overall spatial pattern of high latitude (> 30°S, > 30°N) sedimentation and low latitude (30°S to 30°N) volatilization. These findings highlight the joint regulation of PACs cross-media transport by molecular weight, environmental parameters, PACs type, and demonstrate that global scale monitoring and biological process parameterization are critical for quantifying global PACs fluxes.
 

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