The percentage of wetlands in a catchment accounted for about half of the variance in transformed data for concentrations of dissolved organic carbon (DOC) in 42 Nova Scotian streams draining catchments with 11 different kinds of vegetation. Color increased with DOC, as did total dissolved nitrogen (TDN). The color/DOC and DOC/TDN quotients also rose with increasing DOC, indicating a change in the quality of dissolved organic matter with increasing wetland influence. Dissolved Fe, and to a much lesser extent dissolved A1, showed a strong positive correlation with DOC. Stream pH showed a strong negative correlation with DOC, largely from wetlands, and a strong positive correlation with non-marine Ca ~+ weathered from mineral soils. Non-marine SO4 z-from acid deposition had no apparent influence on stream pH and decreased with increasing streamwater DOC in summer, presumably owing to reduction processes in wetlands that mitigated the effects of acid deposition. Apparently, these reduction processes also produced small amounts of dissolved, non-ionic organic sulfur. Non-marine Ca 2+ was related strongly to the percentage of upland hardwood forests in the catchments. Wetlands exert a profound influence on the chemistry of streams, principally through their export of DOC but also because of reduction reactions in their anerobic peats.

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This paper provides an overview of the results of a study undertaken to provide a basis for predesign evaluation of the effectiveness of options for treatment of municipal surface waters in the province of Nova Scotia. Seasonal samples of raw water were obtained from the fall of 1992 through the fall of 1993 from five sites. Results were compared with a Nova Scotia Department of Health data base of randomly collected samples. For project samples, strong relationships were evident between raw water total organic carbon (TOC) and both colour and trihalomethane formation potential. Laboratory batch tests, supported by plant results, indicated that percentage removals of TOC increase with raw water TOC, and that settling-filtration was more effective than direct filtration for waters with higher raw TOC concentrations. Results of solids settling tests were consistent with TOC results. A treatment optimized for TOC removal also ensured removal of colour. TOC removals by dissolved air flotation followed by filtration exceeded removals by direct filtration or settling-filtration, based on laboratory bench tests, particularly at sites with higher values of raw TOC. Colour removal by dissolved air flotation was consistently higher at all sites. Key words: enhanced coagulation, trihalomethane precursors, total organic carbon, surface water treatment, dissolved air flotation.

Applications of seepage meters in lakes with slight bottom sediments in fractured rock basins have not been reported. A study of the hydrogeology of Long Lake, at Halifax, Nova Scotia, used seepage meters in this situation. Fifteen meters were installed in the 1.7 km2 lake — seven in a line extending from the shore, the remaining eight on the lake periphery. Seepage measurements were made monthly over 1 year. Groundwater levels were measured in boreholes in the fractured granite of the watershed. A positive inflow of groundwater to the lake occurred through the year, seepage flux at the shoreline meters varied from 0.15 to 0.78 mL∙m−2∙s−1, with no consistent seasonal variations. Seepage decreased exponentially with offshore distance. A linear relationship was evident between water levels in a borehole near the shore and rate of seepage at the closest meter. Chloride applied to this borehole was reflected in elevated chloride concentrations in seepage collected by the meter. Key words: seepage meter, groundwater – lake system, fractured rock tracers.