Roland I. Hall

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BACKGROUND The extent to which Alberta oil sands mining and upgrading operations have enhanced delivery of bitumen-derived contaminants via the Athabasca River and atmosphere to the Peace-Athabasca Delta (200 km to the north) is a pivotal question that has generated national and international concern. Accounts of rare health disorders in residents of Fort(More)
Identifying potential regional contamination by Alberta oil sands industrial emissions on sensitive ecosystems like the Peace-Athabasca Delta, ~200 km to the north, requires knowledge of historical contaminant levels and trends. Here we provide some of these critically-needed data, based on analysis of metals in a sediment core from an upland(More)
The downstream accumulation of polycyclic aromatic hydrocarbons (PAHs) in the Peace-Athabasca Delta (PAD), an ecologically important landscape, is a key issue of concern given the rapid development of the oil sands industry in Northern Alberta, Canada. In addition to PAHs derived from industrial activity (i.e., oil sands mining) within the Athabasca(More)
SUMMARY 1. We explored patterns of limnological variables (physical, chemical and biological) with relation to landscape position (expressed as lake order) in 86 study lakes located on shield bedrock in south-central Ontario, Canada. 2. Using A NO V A A NO V A s with lake order as the categorical variable, landscape position explained significant amounts of(More)
Growing concerns over effects of climate warming and other stressors on shallow Arctic lakes and ponds stimulate the need to develop and implement effective protocols to track changes in ecological integrity. This study assesses seasonal and spatial variability of periphytic diatom communities in a shallow Arctic lake in northern Yukon Territory to(More)
Chemical recovery of many acidified lakes in North America has been delayed or reversed as a result of interactions between climatic variability (alterations between drought and nondrought periods) and previously deposited acids stored in wetlands, but effects of this wetland-mediated reacidification phenomenon on aquatic biota remain unknown. We compare(More)
Shallow lakes are dominant features in subarctic and Arctic landscapes and are responsive to multiple stressors, which can lead to rapid changes in limnological regimes with consequences for aquatic resources. We address this theme in the coastal tundra region of Wapusk National Park, western Hudson Bay Lowlands (Canada), where climate has warmed during the(More)
Freshwater ecosystems are increasingly affected by human influences. Since the pre-industrial era, lakes of the Muskoka–Haliburton region of south-central Ontario have had increases in shoreline residential development and acid deposition. Previous research on 54 of these lakes, using sediment cores and diatom-based transfer functions, showed changes in(More)
In this policy perspective, we outline several conditions to support effective science-policy interaction, with a particular emphasis on improving water governance in transboundary basins. Key conditions include (1) recognizing that science is a crucial but bounded input into water resource decision-making processes; (2) establishing conditions for(More)
The annual population growth of the exotic invader Bythotrephes cederstroemi was calculated from the spatial distribution and rate of accumulation of its diagnostic caudal processes in the sediments of Harp Lake, Ontario. To our knowledge, this is the first use of the sediment record to quantify the annual population growth of a zooplankton species on a(More)