Contamination Status of Dioxins in Sediments from Saigon River Estuary, Vietnam

Abstract—Concentrations of dioxins in surface sediments and a sediment core from the coast of southern Vietnam were determined. In surface sediments, concentrations of both PCDD/DFs and coplanar-PCBs were higher in inland than in offshore samples. However, proportion of PCDFs in total PCDD/DFs was higher in inland than in the marine area samples, and it can be presumed that some combustion source might exist in inland acting as a source of PCDD/ DFs to this region. On the other hand, coplanar-PCBs were specifically high in particular locations of inland and marine area, indicating that scattered hotspots may be present both in inland and the marine areas. Various technical PCBs can be suspected as pollution sources depending on the isomer profiles of different commercial mixtures. In core sediment analysis, no temporal trend either in total concentration or isomer profile was observed. 2,3,7,8-TCDD, which was present in chemical defoliants, was not detected in any of the layers analyzed. 2,3,7,8-TCDD which is present in chemical defoliants might have diffused in the ocean or remain in deeper layers than in the depth of from which the sample for the present study was collected. Abbreviations Used: PCDD, polychlorinated dibenzo-p-dioxin; PCDF, polychlorinated dibenzofuran; PCB, polychlorinated biphenyl; TEF, toxic equivalent factor; I-TEQ, toxic equivalent calculated using TEF proposed by NATO in 1988; WHO-TEQ, toxic equivalent calculated using TEF proposed by WHO in 200