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Survey of metabolically essential trace metals in inland lakes and reservoirs across Canada: What constitutes a low metal system?
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Molot, Lewis A.; Schiff, Sherry; Baulch, Helen M.; Curry, R.Allen; Depew, David C.; Dove, Alice; Higgins, Scott N.; Kidd, Karen A.; Korosi, Jennifer B.; Paterson, Andrew M.; Pick, Frances R.; Venkiteswaran, Jason; Watson, Susan B.; Zastepa, Arthur — 2024-09-16 Trace metals are metabolically essential with many proteins dependent on metals for proper functioning yet little is known about the influence of low concentrations on freshwater microbial productivity and diversity. Dissolved iron (Fe), manganese (Mn), zinc (Zn), molybdenum (Mo), nickel (Ni), cobalt (Co), copper (Cu) and vanadium (V) were surveyed in 39 lakes and reservoirs across Canada representing different geology, dominant land uses, lake depth, trophic status and climatic zones. Concentrations varied considerably and cross-Canada patterns were not uniform among the eight metals, but PCA analysis revealed two major patterns: Co, Cu, Ni and V in one group and Fe and Mn in a second group. Sub-nanomolar concentrations of Co and Mo were common while sub-nanomolar concentrations of Zn, V and Ni were less common. Fe and Mn accumulated in the hypolimnion of the six lakes and reservoirs deep enough to thermally stratify with Co and Zn accumulation less common. Mo, Zn and Fe occasionally exceeded Canadian guidelines for protection of aquatic biota. Genomics and Monod growth kinetics were explored for their potential in identifying low metal environments and metal limitation without using metal enrichment bioassays. Metal concentrations in the cross-Canada survey were probably not low enough to limit growth but the impact of low metals on microbial diversity is unknown.
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Phosphorus-only fertilization rapidly initiates large nitrogen-fixing cyanobacteria blooms in two oligotrophic lakes
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Molot, Lewis A.; Higgins, Scott N.; Schiff, Sherry; Venkiteswaran, Jason; Paterson, Michael J.; Baulch, Helen M. — 2021-06-15 Two small, oligotrophic lakes at the IISD-Experimental Lakes Area in northwestern Ontario, Canada were fertilized weekly with only phosphorus (P) in the summer and early fall of 2019. The P fertilization rates were high enough (13.3 µg L-1 added weekly) to produce dense, month-long blooms of N2-fixing Dolichospermum species in both lakes within 9-12 weeks after fertilization began, turning them visibly green without the addition of nitrogen. P-only fertilization increased average seasonal chlorophyll a concentrations and cyanobacteria biomass well above the pre-fertilization levels of 2017 and 2018. Nitrogen (N) content in the epilimnion of thermally stratified Lake 304 and the water column of shallow Lake 303 doubled and P storage in the water column temporarily increased during the blooms. These whole-lake fertilization experiments demonstrate that large cyanobacteria blooms can develop rapidly under high P loading without anthropogenic N inputs, suggesting that aggressive N control programs are unlikely to prevent bloom formation and that P controls should remain the cornerstone for cyanobacteria management.
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History of DOM & DBP in Drinking Water Sources across the Northwest Territories
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Aukes, Pieter; Venkiteswaran, Jason; Schiff, Sherry; English, Michael; Department of Municipal and Community Affairs — 2020-11-27 This dataset is a compilation of public water quality records from the Department of Municipal and Community Affairs (MACA), Government of Northwest Territories for all communities in the Northwest Territories, 1994-2016. Water quality data includes measures of true colour and concentrations of dissolved organic carbon (DOM) and disinfection by-products (DBP), specifically trihalomethane species. Each record includes community and region information, sampling dates, water sampling source, lab information, and DOM and DBP values. <p><p>Data is derived from MACA records available online at https://www.nwtdrinkingwater.ca/operations/water/water_raw.asp
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Data used in 'Size-Based Characterization of Freshwater Dissolved Organic Matter finds Similarities within a Water Body Type across Different Canadian Ecozones'
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Aukes, Pieter; Schiff, Sherry; Venkiteswaran, Jason; Elgood, Richard; Spoelstra, John — 2020-07-17 Field collection of freshwater surface and groundwater samples from five ecozones across Canada. Concentration and composition (via UV-absorbance and size-exclusion chromatography) of dissolved organic matter were analyzed across all sites and compared across hydrologic compartments to identify similarities in dissolved organic matter (DOM).
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Data used in 'Composition Wheels: Visualizing dissolved organic matter using common composition metrics across a variety of Canadian Ecozones'
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Aukes, Pieter; Schiff, Sherry — 2020-12-11 Field collection of surface and groundwaters across Canada for characterization of dissolved organic matter (DOM). DOM was characterized using UV-visible absorbance, size-exclusion chromatography, and elemental ratios (dissolved organic carbon to dissolved organic nitrogen). Measures were compared in all samples to determine which select measures give us the best representation of DOM composition. These were then used to develop a simple visualization tool (Composition Wheel).

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