Pieters R.,University of British Columbia |
Coedy W.,Indian and Northern Affairs Canada |
Ashley K.I.,Ken Ashley and Associates Ltd. |
Lawrence G.A.,University of British Columbia
Canadian Journal of Civil Engineering | Year: 2014
We describe the artificial circulation (destratification) of a pit lake at the Colomac mine site, 220 km north of Yellowknife, NWT, Canada. The pit lake, with a surface area of 17 ha and depth of 110 m, contained relatively saline water contaminated with the mining-related cyanide by-products, thiocyanate and ammonia. As a result of snow and ice melt, the pit lake was intermittently meromictic and cycling of contaminants through the oxygenated surface layer would have taken many years. To accelerate the oxidation process, the pit was artificially circulated using two air diffusers at a depth of 57 m. The pit lake was circulated during the open-water season, from 12 July 2006 for 57 days, and from 17 June 2007 for 89 days. After the first 12 h of operation of the circulation system, the top 37 m of the pit lake was mixed completely; after 34 h, the pit lake was mixed to the depth of the diffusers (57 m); and after approximately 6.5 days, the pit lake was mixed to the bottom. Upon complete mixing, the temperature and conductivity remained uniform during operation of the circulation system, and the concentration of oxygen in the deep water of the pit lake increased significantly. All thiocyanate was oxidized by the end of the first summer, producing ammonia that was depleted after the second summer of circulation. © 2014, NRC Research Press.
Riget F.,University of Aarhus |
Bignert A.,Swedish Museum of Natural History |
Braune B.,Carleton University |
Stow J.,Indian and Northern Affairs Canada |
Wilson S.,Arctic Monitoring and Assessment Programme AMAP Secretariat
Science of the Total Environment | Year: 2010
A statistically robust method was applied to 316 time-series of 'legacy' persistent organic pollutants (POPs) in Arctic biota from marine, freshwater and terrestrial ecosystems with the purpose of generating a 'meta-analysis' of temporal trend data collected over the past two to three decades for locations from Alaska in the west to northern Scandinavian in the east. Information from recently published temporal trend studies was tabulated and comparisons were also drawn with trends in arctic air. Most of the analysed time-series of legacy POP compounds showed decreasing trends, with only a few time-series showing significantly increasing trends. Compounds such as α-HCH, γ-HCH and ΣDDT had a relatively high proportion of time-series showing significantly decreasing trends; ΣCHL had the lowest proportion. β-HCH was an exception, where long-range transport through the ocean, and not the atmosphere, may explain several increasing trends that were detected in the Canadian Arctic. Moving east from the Canadian Arctic there was a trend towards a greater proportion of significantly decreasing trends. Several time-series for DDE and ΣDDT showed significantly non-exponential trends, most often with a period of relative stability followed by a decrease. The median 'minimum detectable annual change within a 10-year period' for all of the time-series considered was 12% which did not meet the desirable level of statistical power capable of detecting a 5% annual change with a significance level of 5% within a 10-year period. The trends observed in the biota were consistent with decreasing trends of legacy POPs reported for Arctic air which appear to follow historic decreases in emissions. However, recent decreases in air are also starting to show signs of levelling off which may be an indication that atmospheric concentrations and, consequently those in the biota, are being less driven by primary sources and more by environmental processes and degradation. © 2009 Elsevier B.V.
Gibson J.J.,Alberta Research Council |
Reid R.,Indian and Northern Affairs Canada
Journal of Hydrology | Year: 2010
Stable isotopes of water, oxygen-18 and deuterium, were measured at biweekly to monthly intervals during the open-water season in a small, headwater lake (Pocket Lake, 4.8 ha) near Yellowknife Northwest Territories, and concurrently in a nearby string-of-lakes watershed (Baker Creek, 137 km2) situated in the subarctic Precambrian Shield region. As measured in water samples collected over a 12 year period (1997-2008), the levels of evaporative isotopic enrichment in both lake and watershed outflow were differentially offset, and seasonal variations were found in both to be driven by variations in open-water evaporation. Systematic differences measured in the magnitude of the offset between the lake and watershed outflow are interpreted as being caused by changes in the effective drainage area contributing to runoff. Based on the observed and extremely consistent relationship between isotopic compositions of lake water and watershed outflow (r2 = 0.849, p < 0.001) we extend the analysis of open-water evaporation losses and effective drainage areas back to 1991 when less-frequent water sampling at the sites commenced. This 18-year record serves to demonstrate for the first time the expected variability in the evaporation and transpiration partitioning, upper limits on the effective drainage area, and isotopic signals transferred downstream in a typical shield drainage system within the Mackenzie Basin. © 2009 Elsevier B.V.
Chang W.,McGill University |
Dyen M.,McGill University |
Spagnuolo L.,Indian and Northern Affairs Canada |
Simon P.,Qikiqtaaluk Environmental |
And 2 more authors.
Chemosphere | Year: 2010
This study evaluates the feasibility of landfarming biotreatment of petroleum-contaminated soils obtained from a sub-Arctic site at Resolution Island, Nunavut, Canada, and evaluates the changes in composition of the semi- and non-volatile petroleum hydrocarbon fractions during the biotreatment. Pilot-scale landfarming experiments were conducted in a laboratory in soil tanks under temperature profiles representative of the 3-year site air temperatures in July and August where temperature varied uniformly between 1°C and 10°C over 10d. The site soils were acidic and N-deficient, but contained indigenous populations of hydrocarbon-degrading microorganisms. Biostimulation with nitrogen and phosphorus nutrient amendments to achieve CTPH:N:P molar ratio of 100:9:1, and CaCO3 amendment at 2000mgKg-1 for maintaining neutral pH, and periodic 10-day tilling, reduced total petroleum hydrocarbon (TPH) concentrations by up to 64% over a 60-day period. The rate and extent of semi-volatile (F2: >C10-C16) and non-volatile (F3: >C16-C34) petroleum hydrocarbon fractions in the landfarms containing higher initial TPH levels (∼2000mgKg-1) and lower TPH levels (∼1000mgKg-1) were compared. Significant biodegradation of the F2 and F3 fractions occurred in both of those systems. First-order biodegradation rate constants of up to 0.019±0.001d-1 were determined for the F3 hydrocarbon fraction and were similar to the F2 fraction biodegradation rate constants of up to 0.024±0.005d-1. Biodegradation profiles of the C14, C16 and C18 alkanes revealed that at TPH concentrations above 1000mgKg-1 these compounds are degraded concurrently, whereas below 1000mgKg-1 the higher-molecular weight alkanes are preferentially degraded. After the 60-day treatment period, the TPH concentration was approximately 500mgKg-1, and the residual TPH mass was largely associated with particles and aggregated particles with diameters of 0.6-2mm, rather than the larger or finer particles and aggregates. © 2010 Elsevier Ltd.
Spence C.,Environment Canada |
Guan X.J.,University of Saskatchewan |
Phillips R.,University of Saskatchewan |
Hedstrom N.,Environment Canada |
And 2 more authors.
Hydrological Processes | Year: 2010
Storage heterogeneity effects on runoff generation have been well documented at the hillslope or plot scale. However, diversity across catchments can increase the range of storage conditions. Upscaling the influence of small-scale storage on streamflow across the usually more heterogeneous environment of the catchment has been difficult. The objective of this study was to observe the distribution of storage in a heterogeneous catchment and evaluate its significance and potential influence on streamflow. The study was conducted in the subarctic Canadian Shield: A region with extensive bedrock outcrops, shallow predominantly organic soils, discontinuous permafrost and numerous water bodies. Even when summer runoff was generated from bedrock hillslopes with small storage capacities, intermediary locations with large storage capacities, particularly headwater lakes, prevented water from transmitting to higher order streams. The topographic bounds of the basin thus constituted the maximum potential contributing area to streamflow and rarely the actual area. Topographic basin storage had little relation to basin streamflow, but hydrologically connected storage exhibited a strong hysteretic relationship with streamflow. This relationship defines the form of catchment function such that the basin can be defined by a series of storing and contributing curves comparable with the wetting and drying curves used in relating tension and hydraulic conductivity to water content in unsaturated soils. These curves may prove useful for catchment classification and elucidating predominant hydrological processes. Copyright © 2009 John Wiley & Sons, Ltd and Her Majesty the Queen in right of Canada.
Spence C.,Environment Canada |
Kokelj S.V.,Indian and Northern Affairs Canada |
Ehsanzadeh E.,Environment Canada
IAHS-AISH Publication | Year: 2011
Autumn runoff events rivalling the size of the spring freshet peak as well as sustained winter streamflow have become more common in the northwestern Canadian Shield since the mid 1990s. Previous circumpolar and large regional-scale studies have implied these phenomena are due to increased water inputs from thawing permafrost. However, results from an investigation of the precipitation and temperature trends provide an alternate explanation for this region. A shift from a nival to a combined nival/pluvial streamflow regime, particularly in small watersheds, can be attributed to trends in the timing and state of autumn precipitation. Because these trends are subtle, careful consideration of hydrological processes, and the temporal and landscape context in which they operate, is important when attempting to explain the observed shifts in regional streamflow. It is important to correctly explain why streamflow regimes are changing because of close relationships with variations in ground thermal conditions and aquatic chemistry, which are of significance to society. These relationships are discussed. Copyright © 2011 IAHS Press.
Parsons M.A.,University of Colorado at Boulder |
Godoy O.,Norwegian Meteorological Institute |
Ledrew E.,University of Waterloo |
De Bruin T.F.,Netherlands Institute for Sea Research |
And 3 more authors.
Journal of Information Science | Year: 2011
Much attention has been given to the challenges of handling massive data volumes in modern data-intensive science. This paper examines an equally daunting challenge-the diversity of interdisciplinary data, notably research data, and the need to interrelate these data to understand complex systemic problems such as environmental change and its impact. We use the experience of the International Polar Year 2007-8 (IPY) as a case study to examine data management approaches seeking to address issues around complex interdisciplinary science. We find that, while technology is a critical factor in addressing the interdisciplinary dimension of the data intensive science, the technologies developing for exa-scale data volumes differ from those that are needed for extremely distributed and heterogeneous data. Research data will continue to be highly heterogeneous and distributed and will require technologies to be much simpler and more flexible. More importantly, there is a need for both technical and cultural adaptation. We describe a vision of discoverable, open, linked, useful, and safe collections of data, organized and curated using the best principles and practices of information and library science. This vision provides a framework for our discussion and leads us to suggest several short- and long-term strategies to facilitate a socio-technical evolution in the overall science data ecosystem. © 2011 Chartered Institute of Library and Information Professionals.
Generation of Priority Research Questions to Inform Conservation Policy and Management at a National Level [Generación de Preguntas de Investigación Prioritarias para Informar a las Políticas y Gestión de la Conservación a Nivel Nacional]
Rudd M.A.,University of York |
Beazley K.F.,Dalhousie University |
Cooke S.J.,Carleton University |
Fleishman E.,University of California at Santa Barbara |
And 29 more authors.
Conservation Biology | Year: 2011
Integrating knowledge from across the natural and social sciences is necessary to effectively address societal tradeoffs between human use of biological diversity and its preservation. Collaborative processes can change the ways decision makers think about scientific evidence, enhance levels of mutual trust and credibility, and advance the conservation policy discourse. Canada has responsibility for a large fraction of some major ecosystems, such as boreal forests, Arctic tundra, wetlands, and temperate and Arctic oceans. Stressors to biological diversity within these ecosystems arise from activities of the country's resource-based economy, as well as external drivers of environmental change. Effective management is complicated by incongruence between ecological and political boundaries and conflicting perspectives on social and economic goals. Many knowledge gaps about stressors and their management might be reduced through targeted, timely research. We identify 40 questions that, if addressed or answered, would advance research that has a high probability of supporting development of effective policies and management strategies for species, ecosystems, and ecological processes in Canada. A total of 396 candidate questions drawn from natural and social science disciplines were contributed by individuals with diverse organizational affiliations. These were collaboratively winnowed to 40 by our team of collaborators. The questions emphasize understanding ecosystems, the effects and mitigation of climate change, coordinating governance and management efforts across multiple jurisdictions, and examining relations between conservation policy and the social and economic well-being of Aboriginal peoples. The questions we identified provide potential links between evidence from the conservation sciences and formulation of policies for conservation and resource management. Our collaborative process of communication and engagement between scientists and decision makers for generating and prioritizing research questions at a national level could be a model for similar efforts beyond Canada.©2010 Society for Conservation Biology.