The global phase-out of conventional polybrominated diphenyl ethers (PBDEs) has led to the rapid production and widespread use of novel brominated flame retardants (NBFRs), particularly decabromodiphenyl ethane (DBDPE). However, their environmental fate and ecological risks in marine systems remain poorly understood. The Bohai Sea, a semi-enclosed shallow sea strongly influenced by terrestrial inputs and complex hydrodynamics, provides an ideal setting for investigating the environmental behavior of these emerging contaminants.
Surface water samples collected during three seasonal cruises (autumn 2021, spring 2022, and summer 2022) were analyzed for fifteen legacy and novel brominated flame retardants in dissolved and particulate phases. Combined with high-resolution CTD observations and nutrient measurements, these data were used to investigate their spatiotemporal distributions and controlling environmental processes.
Two major contamination hotspots were identified in Laizhou Bay and the outer Yellow River Estuary, reflecting industrial emissions and riverine suspended matter inputs, respectively. BDE209 and DBDPE dominated the contaminant profiles, indicating a regional transition from legacy PBDEs to alternative flame retardants. More than 95% of the target compounds occurred in the particulate phase, consistent with their strong hydrophobicity. Seasonal variations showed that particulate BDE209 was strongly influenced by spring sediment resuspension and summer river discharge, whereas DBDPE exhibited relatively stable concentrations, suggesting sustained atmospheric deposition and continuous point-source emissions. Correlations with turbidity and chlorophyll-a further revealed that suspended particulate matter and phytoplankton-driven biological pumping play key roles in regulating particle partitioning and vertical transport of hydrophobic flame retardants.
These findings improve understanding of the transport and fate of legacy and emerging brominated flame retardants in coastal seas and provide a scientific basis for ecological risk assessment and contaminant management in the Bohai Sea.
Keywords: Brominated flame retardants; Phase partitioning; Multi-seasonal dynamics; Bohai Sea