Recherche

Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Survey of metabolically essential trace metals in inland lakes and reservoirs across Canada: What constitutes a low metal system?
Borealis
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.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Phosphorus-only fertilization rapidly initiates large nitrogen-fixing cyanobacteria blooms in two oligotrophic lakes
Borealis
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.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Data for: Quantifying arsenic post-depositional mobility in lake sediments impacted by gold ore roasting in sub-arctic Canada using inverse diagenetic modelling
Borealis
Leclerc, Émilie; Couture, Raoul-Marie; Venkiteswaran, Jason — 2021-09-09 The extraction of gold from arsenopyrite at Giant Mine, near Yellowknife, generated arsenic trioxide between 1940 and 2004. This contamination went beyond the immediate mining sites via emission to the atmosphere and subsequent deposition on soils and lakes. At present, the extent of this legacy is poorly known. Yellowknife is in the subarctic area, one of the most rapidly warming areas in the world. As climate warms, the permafrost melts and the decomposition rates for organic matter accelerates. This increases the load of dissolved organic matter, promotes greenhouse gas emissions and increases the mobility of contaminants in the water.<p><p> The objectives of this research project were to determine the extent and history of arsenic contamination in eight lakes along an 80 km transect northwest from the mine, using the sediments as an environmental archive. Because arsenic is mobile in sediment, the mobility of arsenic and its possible remobilisation in water were assessed. <p><p>The water content (porewater) of sediment samples was analysed by inductively coupled plasma mass spectrometry (ICP-MS) for metals and metalloids. Acid volatile sulfides (AVS) were analysed by ultraviolet-visible spectroscopy after extractions. Comparison of the concentration profile obtained for different elements allows speculating on the reactions that occur in the sediment. <p><p>Finally, inverse diagenetic modelling was performed to determine arsenic reaction rates and the fluxes. This information was then used to discriminate between natural and anthropogenic arsenic sources, and to quantify its mobility in sediments and its probabilities of remobilization to lake water.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Bathymetric and hypsographic data for IISD-ELA Lakes L438, L627, and L628
Borealis
Atkins, Jordyn; Venkiteswaran, Jason — 2020-12-08 Bathymetric and hypsographic data and maps for IISD-ELA Lakes L438, L627, and L628. Field data were collected with a Humminbird HELIX 5 CHIRP GPS G2 Shapefiles and bathymetric maps were generated in ReefMaster 2. These lakes did not previously have bathymetric and hypsographic data available for them. These lakes are part of a lake-size survey and the L626 Diversion project.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Data for: Evaluating spatiotemporal patterns of arsenic, antimony, and lead deposition from legacy gold mine emissions using lake sediment records
Borealis
Jasiak, Izabela; Wolfe, Brent; Hall, Roland; Venkiteswaran, Jason — 2021-09-09 In the absence of long-term environmental monitoring prior to and during resource development, identifying the extent of pollution is challenging but important for assessing risks to ecosystem health. Legacy pollution from Giant Mine in the Northwest Territories is a concern because while gold smelting operations ceased in the late 1990s, the fine, toxic dust arsenic trioxide dispersed into the atmosphere, potentially creating repositories in the surrounding landscape. Lake water surveys and the sampling of surficial sediment have identified a confined emissions footprint within a 30-km radius of the mine. However, these measurements may not capture the range of aerial deposition of emissions from the mine, particularly peak emissions released during the 1950s. Paleolimnological studies from far-field locations have shown evidence of arsenic enrichment coinciding with the timing of peak mine emissions during the 1950s, suggesting further research is needed to characterize stores of legacy metals derived from Giant Mine pollution.<p><p>To address this need, as part of the Sub-Arctic Metal Mobility Study, temporal patterns of metals (arsenic, antimony, and lead) deposition and hydrological conditions were reconstructed from sediment cores collected from eight lakes along an 80-km transect northwest of Yellowknife, following the prevailing wind direction. Two sediment cores were collected from each lake by using a Uwitec gravity corer fitted with PVC tubes (86-mm internal diameter). These lake sediment cores provide further characterization of the Giant Mine emission footprint, and the depositional and post-depositional history of arsenic and other metals in sub-arctic lakes and their catchments.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Data for: Blooms and flows: effects of variable hydrology and management on reservoir water quality
Borealis
Painter, Kristin; Venkiteswaran, Jason; Baulch, Helen M. — 2023-02-10 Flow management has the potential to significantly affect water quality. Shallow lakes in arid regions are especially susceptible to flow management changes which can have important implications for the formation of cyanobacterial blooms. Here, we reveal water quality shifts across a gradient of managed source water inflow regimes. Using in situ monitoring data, we studied a seven-year time span during which inflows to a shallow, eutrophic drinking water reservoir transitioned from primarily natural landscape runoff (2014 to 2015) to managed flows from a larger upstream reservoir (Lake Diefenbaker; 2016 to 2020) and identified significant changes in cyanobacteria (as phycocyanin) using generalized additive models to classify cyanobacterial bloom formation. We then connected changes in water source with shifts in chemistry and the occurrence of cyanobacterial blooms using principal components analysis. Phycocyanin was greater in years with managed reservoir inflow from mesotrophic Lake Diefenbaker (2016 to 2020) but dissolved organic matter (DOM) and specific conductivity, important determinants of drinking water quality, were greatest in years when landscape runoff dominated lake water source (2014 to 2015). Most notably, despite changing rapidly, it took multiple years for lake water to return to a consistent and reduced level of DOM after managed inflows from upstream Lake Diefenbaker were resumed, an observation that underscores how resilience may be hindered by weak resistance to change and slow recovery. Environmental flows for water quality are rarely defined yet here it appears trade-offs exist between poor water quality via elevated conductivity and DOM, and higher bloom risk. Taken together, our findings have important implications for water managers who must protect water quality while adapting to projected hydroclimatic change.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
History of DOM & DBP in Drinking Water Sources across the Northwest Territories
Borealis
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
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Data for: Early and late cyanobacterial bloomers in a shallow, eutrophic lake
Borealis
Painter, Kristin; Venkiteswaran, Jason; Simon, Dana F.; Duy, Sung Vo; Sauvé, Sébastien; Baulch, Helen M. — 2022-07-14 This dataset contains data and code for <a href="https://doi.org/10.1002/essoar.10510183.2">"Early and Late Cyanobacterial Bloomers in a Shallow, Eutrophic Lake"</a>, published in <i>Earth and Space Science Open Archive</i>, 2022. Cyanobacterial blooms present challenges for water treatment, especially in regions like the Canadian prairies where poor water quality intensifies water treatment issues. Buoyant cyanobacteria that resist sedimentation present a challenge as water treatment operators attempt to balance pre-treatment and toxic disinfection by-products. Here, we used microscopy to identify and describe the evolution of cyanobacterial species in Buffalo Pound Lake, a key drinking water supply. We used indicator species analysis to identify temporal grouping structures throughout two sampling seasons from May to October 2018 and 2019. Our findings highlight two key cyanobacterial bloom phases – a mid-summer diazotrophic bloom of Dolichospermum spp. and an autumn Planktothrix agardhii bloom. Dolichospermum crassa and Woronchinia compacta served as indicators of the mid-summer and autumn bloom phases, respectively. Different cyanobacterial metabolites were associated with the distinct bloom phases in both years: toxic microcystins were associated with the mid-summer Dolichospermum bloom and some newly monitored cyanopeptides (anabaenopeptin A and B) with the autumn Planktothrix bloom. Despite forming a significant proportion of the autumn phytoplankton biomass (> 60%), the Planktothrix bloom had previously not been detected by sensor or laboratory-derived chlorophyll-a. Our results demonstrate the power of targeted taxonomic identification of key species as a tool for managers of bloom-prone systems. Moreover, we describe an autumn Planktothrix agardhii bloom that has the potential to disrupt water treatment due to its evasion of detection. Our findings highlight the importance of identifying this autumn bloom given the expectation that warmer temperatures and a longer ice-free season will become the norm.
Wilfrid Laurier University Dataverse Translation missing: fr.blacklight.search.logo
Data used in 'Size-Based Characterization of Freshwater Dissolved Organic Matter finds Similarities within a Water Body Type across Different Canadian Ecozones'
Borealis
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).

Instructions pour la recherche cartographique

1.Activez le filtre cartographique en cliquant sur le bouton « Limiter à la zone sur la carte ».
2.Déplacez la carte pour afficher la zone qui vous intéresse. Maintenez la touche Maj enfoncée et cliquez pour encadrer une zone spécifique à agrandir sur la carte. Les résultats de la recherche changeront à mesure que vous déplacerez la carte.
3.Pour voir les détails d’un emplacement, vous pouvez cliquer soit sur un élément dans les résultats de recherche, soit sur l’épingle d’un emplacement sur la carte et sur le lien associé au titre.
Remarque : Les groupes servent à donner un aperçu visuel de l’emplacement des données. Puisqu’un maximum de 50 emplacements peut s’afficher sur la carte, il est possible que vous n’obteniez pas un portrait exact du nombre total de résultats de recherche.

(source : Wilfrid Laurier University Dataverse) AND (auteur : Venkiteswaran, Jason)

Limiter par :

Effacer tout

au