Post-Chernobyl 134Cs and 137Cs Levels at Some Localities in Northern Canada

Samples of lichen, moss and caribou meat from the high and central arctic regions of Canada were measured for 137Cs due to the Chernobyl accident of April 1986. They were compared to lichen samples from the boreal area of Wood Buffalo National Park, Alberta, and to moss samples from the temperate Niagara Escarpment of southern Ontario. Lichens from Ellesmere Island and mosses from the Niagara Escarpment had no detectable Chernobyl 137Cs. Lichens from the central Arctic showed a 137Cs increase of about 14% above the persistent burden from the past atmospheric nuclear weapons testing. Mosses and lichens from Wood Buffalo National Park showed an average 137Cs increase of 19% due to Chernobyl fallout. In absolute terms, the contribution of Chernobyl fallout over Canadian northern regions was non-significant compared to the depositions experienced by countries such as the U.S.S.R., Sweden, Norway and some Central European countries.Key words: Chernobyl, 134.137Cesium, fallout radionuclides in northern Canada, lichen samples, caribou samplesMots clés: Chernobyl, 1343137Césium, retombées de radionucléides dans le Nord canadien, échantillons de lichens, échantillons de caribo

The Changing Climate of the Arctic

The first and strongest signs of global-scale climate change exist in the high latitudes of the planet. Evidence is now accumulating that the Arctic is warming, and responses are being observed across physical, biological, and social systems. The impact of climate change on oceanographic, sea-ice, and atmospheric processes is demonstrated in observational studies that highlight changes in temperature and salinity, which influence global oceanic circulation, also known as thermohaline circulation, as well as a continued decline in sea-ice extent and thickness, which influences communication between oceanic and atmospheric processes. Perspectives from Inuvialuit community representatives who have witnessed the effects of climate change underline the rapidity with which such changes have occurred in the North. An analysis of potential future impacts of climate change on marine and terrestrial ecosystems underscores the need for the establishment of effective adaptation strategies in the Arctic. Initiatives that link scientific knowledge and research with traditional knowledge are recommended to aid Canada’s northern communities in developing such strategies.Les premiers signes et les signes les plus révélateurs attestant du changement climatique qui s’exerce à l’échelle planétaire se manifestent dans les hautes latitudes du globe. Il existe de plus en plus de preuves que l’Arctique se réchauffe, et diverses réactions s’observent tant au sein des systèmes physiques et biologiques que sociaux. Les incidences du changement climatique sur les processus océanographiques, la glace de mer et les processus atmosphériques s’avèrent évidentes dans le cadre d’études d’observation qui mettent l’accent sur les changements de température et de salinité, changements qui exercent une influence sur la circulation océanique mondiale – également appelée circulation thermohaline – ainsi que sur le déclin constant de l’étendue et de l’épaisseur de glace de mer, ce qui influence la communication entre les processus océaniques et les processus atmosphériques. Les perspectives de certains Inuvialuits qui ont été témoins des effets du changement climatique font mention de la rapidité avec laquelle ces changements se produisent dans le Nord. L’analyse des incidences éventuelles du changement climatique sur les écosystèmes marin et terrestre fait ressortir la nécessité de mettre en oeuvre des stratégies d’adaptation efficaces dans l’Arctique. Des initiatives reliant les recherches et connaissances scientifiques aux connaissances traditionnelles sont recommandées afin de venir en aide aux collectivités du Nord canadien pour que celles-ci puissent aboutir à de telles stratégies

Warming shortens flowering seasons of tundra plant communities

Advancing phenology is one of the most visible effects of climate change on plant communities, and has been especially pronounced in temperature-limited tundra ecosystems. However, phenological responses have been shown to differ greatly between species, with some species shifting phenology more than others. We analysed a database of 42,689 tundra plant phenological observations to show that warmer temperatures are leading to a contraction of community-level flowering seasons in tundra ecosystems due to a greater advancement in the flowering times of late-flowering species than early-flowering species. Shorter flowering seasons with a changing climate have the potential to alter trophic interactions in tundra ecosystems. Interestingly, these findings differ from those of warmer ecosystems, where early-flowering species have been found to be more sensitive to temperature change, suggesting that community-level phenological responses to warming can vary greatly between biomes

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Recovery of Tundra Vegetation after Overgrazing by Caribou in Arctic Canada

During the summer of 1987, 500-1000 caribou became stranded on Rideout Island in Bathurst Inlet, Northwest Territories. The 40 sq/km island did not have sufficient forage to support the animals until freeze-up, and the caribou eventually died from malnutrition after severely overgrazing the vegetation. In late July 1988, we found that most of the vascular vegetation on Rideout Island had recovered considerably. Vascular species composition and cover in the two major plant communities were comparable to those in similar communities on the adjacent, moderately grazed mainland. The willows (Salix spp.) and graminoid species were vigorous, and no differences were found in biomass allocation patterns of Salix lanata plants between the island and the mainland. However, essentially all of the macrolichen biomass was eliminated on the island, and full recovery could take more than 20 years.Key words: caribou, caribou range ecology, overgrazing, Bathurst Inlet, arctic vegetation, Salix spp., Betula spp.Mots clés: caribou, écologie du territoire du caribou, broutage excessif, inlet de Bathurst, vegetation arctique, esp. Salix, esp. Betul