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 Fjord and at two selected sites in the St Lawrence Estuary in 1991. Total 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 ng 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 contained detectable amounts of chlorinated dibenzodioxins and dibenzofurans, apart from the North Atlantic cod (Gadus morhua). The highest concentrations (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 opilio) caught in Saguenay, and in crab and whelk (Buccinum undatum) collected in Bale des Anglais. Nordic shrimp (Pandalus borealis) seems less 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 halibut (Reinhardtius hippoglossoides) caught in the Saguenay Fjord contained 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 series of results, benthic organisms and fish from the Saguenay Fjord and the north shore of the St Lawrence Estuary are exposed to low levels of PCDDs and PCDFs, and carry tissue concentrations well below international guidelines for fisheries products.