This study investigates four classes of persistent organic pollutants, specifically PCDD/Fs, PBDD/Fs, dl-PCBs, and PBDEs in 20 sediment samples collected from Daya Bay. All target compounds were extracted and analyzed via GC-HRMS. Source identification was performed using PCA and PMF on congener concentration data, supplemented by comprehensive information on pollution sources within and around Daya Bay. The results reveal PCDD/F concentrations were notably high, primarily deriving from the historical application of sodium pentachlorophenol in the surrounding area to control the snail oncomelania. In contrast, PBDD/Fs were detected at relatively low concentrations, with multiple distinct sources identified: thermal and combustion processes, atmospheric photochemical degradation of PBDEs, and potential biosynthesis of tetra- and penta-PBDDs by marine algae. dl-PCBs were present at low concentrations, attributed to thermal processes involving commercial PCB-containing products. PBDEs concentrations showed substantial variability, linked to commercial formulations of penta-BDE, octa-BDE, and deca-BDE. TOC and PAHs in sediments were determined. The correlation analysis of target pollutants, PAHs and TOC concentrations in sediments shows PCDD/Fs closely associated with TOC, and PAHs well interrelated with PCBs, supporting above source interpretations. The total toxic equivalent concentrations of PCDD/Fs, PBDD/Fs, and dl-PCBs were generally below the thresholds associated with high risk to mammals, as defined by the U.S.EPA. For PBDEs, all sampling sites exhibited low to moderate ecological risk. To our knowledge, this study is the first comprehensive report on the concentrations of PCDD/Fs, PBDD/Fs, and dl-PCBs in Daya Bay sediments, providing valuable insights for the environmental management and protection of Daya Bay.
Keywords: PBDD/Fs; PBDEs; PCDD/Fs; Sediments; The Daya Bay; dl-PCBs.
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