The effects of bleached kraft mill effluent on aquatic macrophyte communities in a lake system on the northern shore of Lake Superior

This research focuses on assessing the major effects that bleached kraft mill effluent (BKME) has on aquatic macrophyte communities of inland lakes. Research included three areas, the first involved a survey of water and sediment quality and vegetation distribution, diversity and biomass in three lakes, within the Terrace Bay study area. A comparison of trophic parameters was made between the three lakes, which differ in their exposure to BKME.;The impacts of BKME on lake limnology, included a reduction in available light and dissolved oxygen. The water temperature, conductivity and alkalinity of exposed lakes were elevated while loading of receiving waters and sediments with organic and inorganic nutrients occured. The result is a reduction in total biomass and species diversity and changes in species composition, to favour emergent aquatic macrophytes over submersed and floating leaf species.;The effect of depth on the growth of aquatic macrophytes within a lake that forms part of the effluent stream from the pulp paper mill was investigated. All 8 major aquatic macrophyte species were able to survive transplanting and grow within the exposed lake water and sediment, when propagated in water levels above the average secchi depth of 12 cm.;An investigation was conducted of the levels of congeners of polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated dibenzofuran (PCDF) in the sediment and aquatic vegetation of the two lakes exposed to BKME. Both these organochlorine groups have historically been measured in BKME and widely reported as anthropogenic xenotoxins.;The levels of PCDD/PCDF were found to be elevated in all aquatic macrophytes with higher levels being found in submersed species than emergents.;The PCDD/PCDF homologue profiles were similar for the lake sediments and the aquatic vegetation, with total levels in the three lakes, reflecting the exposure history to BKME.