Brian G. Brownlee

Contaminant sources, distribution and fate in the Athabasca, Peace and Slave River Basins, Canada

Northern river ecosystems worldwide are under increasing environmental stress from degrading developments that influence water quality and associated ecological integrity. In particular, contaminant-related threats to these systems are rising from enhanced industrial and municipal effluent discharges along with elevated non-point source inputs related to land-use activities such as forestry, agriculture, mining and long-range atmospheric transport. In this regard, the contaminants program of the Northern River Basins Study (NRBS) in western Canada identified key contaminant sources to the Athabasca, Slave and Peace river basins (particularly related to pulp-mill developments) and assessed their environmental fate and distribution in water and sediments. The study also developed and employed new analytical approaches and generated improved models to predict contaminant transport and fate in the aquatic environment and related food webs. Consequently the study focused on those contaminant families identified in characterization studies as arising from key point- and non-point sources within the basins or as being of greatest toxicological significance. These included resin acids, polychlorinated dioxins and furans, polychlorinated biphenyls, chlorinated phenolics, polyaromatic hydrocarbons and selected heavy metals such as mercury. Low or non-detectable concentrations of a number of contaminant groups were found in the ambient water phase including chlorinated phenolics, some chlorinated dioxins and furans and some resin acids. For both suspended and depositional sediments, significant declines were observed over the study period for the major chlorinated contaminant groups tested, correlating directly with the implementation of improved effluent treatment in many of the pulp mills located in the basins. In general, the environmental levels of chlorinated organic and metal contaminants in water or sediments were low and within Canadian health or environmental guidelines. It is hoped that the approaches used and lessons learned from the NRBS will be of use to others assessing contaminant and multiple stressor issues in other large river ecosystems.

Occurrence of the Odor Compounds, 2-Methylisoborneol and Geosmin in Eastern Lake Ontario and the Upper St. Lawrence River

Abstract Unpleasant tastes and odors in drinking water from the upper St. Lawrence River were investigated in the fall of 1996 and 1997 as the result of increasing taste and odor events in recent years. Taste and odor events resulted in widespread public reaction to the earthy/musty tasting water produced and a need for accurate information to assist water treatment efforts. The presence of geosmin, (trans, trans-1,10-dimethyl-9-decalol) and 2-methylisoborneol (MIB2, 1,2,7,7-tetramethyl-exobicyclo[2.2.1]heptan-2-ol), the most common causes worldwide of earthy and musty odors in water, were investigated in eastern Lake Ontario and the upper St. Lawrence River. Gas chromatography-mass spectrometry was used for quantitation and confirmation of the presence of these compounds in water samples. Both geosmin and MIB2 were detected in river water samples at concentrations ranging from 5 to 20 ng/L and 2 to 25 ng/L, respectively. The compounds were also detected in southern coastal lake water which serves as a source to the St. Lawrence River, but not in mid-lake samples. Similar levels of geosmin and MIB2 were detected in untreated Lake St. Lawrence water, in samples taken following pre-chlorination for zebra mussel control, and in samples taken following conventional treatment at a water filtration plant.

Is Lake Ontario the Source of Taste and Odor Compounds to the Upper St. Lawrence River

Abstract The south and east coastal currents of Lake Ontario were investigated to determine if they serve as the major source of the common odour compounds, 2-methylisoborneol (MIB) and geosmin (GM), to the St. Lawrence River (SLR). MIB and GM at low parts per trillion levels produce earthy-musty off-tastes in drinking waters. Previous investigations in 1996 and 1997 identified the presence of GM and MIB in SLR and in the southern coastal jet of Lake Ontario, which contributes the bulk of the summertime flow to the St. Lawrence River. Water samples were collected in July and September 1998 during cruises of Lake Ontario and the SLR, extracted shipboard and analyzed for MIB and GM. In July, both compounds were detected only in the SLR, but were found in both Lake Ontario and SLR stations in September. However, MIB and GM were found at higher levels in the St. Lawrence River (17 to 60 ng/L and 2 to 18 ng/L, respectively) than in samples from the Lake Ontario coastal current (0.5 to 10 ng/L and