POLYCHLORINATED DIBENZO-P-DIOXINS AND DIBENZOFURANS IN SEDIMENTS AND BIOTA OF THE SAGUENAY FJORD AND THE ST-LAWRENCE ESTUARY

Sediment samples and marine organisms were collected in the Saguenay F jord and at two selected sites in the St Lawrence Estuary in 1991. Tot al PCDDs and total PCDFs ranged from 22 to 352 acid 29 to 188 ng kg(-1 ), respectively in Saguenay sediments, while total PCDFs reached 287 n g kg(-1) in Bale des Anglais, a small and deep bay of the St Lawrence Estuary impacted by PCBs during the 1970s. All biological samples cont ained detectable amounts of chlorinated dibenzodioxins and dibenzofura ns, apart from the North Atlantic cod (Gadus morhua). The highest conc entrations (up to 59.7 ng kg(-1) total PCDFs and 2.54 ng kg(-1) 2,3,7, 8- T4CDD Equivalent (TCDD TEQ)) were observed in crab (Chionoecetes op ilio) caught in Saguenay, and in crab and whelk (Buccinum undatum) col lected in Bale des Anglais. Nordic shrimp (Pandalus borealis) seems le ss contaminated with a maximum total PCDDs and PCDFs concentration of 14.0 ng kg(-1) and TCDD TEQ never exceeding 0.7 ng kg(-1). Greenland h alibut (Reinhardtius hippoglossoides) caught in the Saguenay Fjord con tained only 2,3,7,8 substituted congeners in their tissues leading to a very low average TCDD TEQ of 1.66 ng kg(-1). Based upon this first s eries of results, benthic organisms and fish from the Saguenay Fjord a nd the north shore of the St Lawrence Estuary are exposed to low level s of PCDDs and PCDFs, and carry tissue concentrations well below inter national guidelines for fisheries products.