A HISTORY OF OCTACHLORODIBENZO-PARA-DIOXIN, 2,3,7,8-TETRACHLORODIBENZOFURAN, AND 3,3',4,4'-TETRACHLOROBIPHENYL CONTAMINATION IN HOWE SOUND, BRITISH-COLUMBIA

Six pulp mills using chlorine bleach discharge effluent into the Strait of Georgia, British Columbia. Fisheries were closed around the mills when dioxins and furans were measured in sediments and edible seafood. We report here the first measurements made for a dioxin (OCDD), a furan (2,3,7,8-TCDF), and a PCB (77) on three dated box cores collected from the region. OCDD is widely distributed, first appears in the sediments in approximately 1940, reaches a maximum in 1970, and probably has an atmospheric source. In contrast, 2,3,7,8-TCDF is concentrated near pulp mills and has been accumulating in the sediments since approximately 1965. PCB 77 correlates well with OCDD and is probably supplied from the atmosphere.