摘要:

The extremity of winter conditions in the present-day polar regions is unique on Earth. Each year organisms are subjected to extremes of temperature and depending on latitude, prolonged periods of darkness. Organisms have adapted to these extremes through a variety of overwintering strategies that range from physiological changes to alterations in geographical distributions. Some adaptations are specific to just a few taxa, such as huddling by penguins, a strategy that is also seen in some Arctic mammals. However, other strategies are common to a wide diversity of taxa, such as fat storage throughout the winter or migratory avoidance behavior. Although many organisms have specifically adapted to polar conditions, it is also apparent that for many, survival of the Antarctic winter draws upon an inherent phenotypic plasticity particularly amongst the invertebrates. In this review the adaptations of a wide range of organisms to the polar winter environment are discussed. This review concentrates on the Antarctic, although the Arctic is discussed for comparison where appropriate.Keywords: winter, overwintering, polar, Arctic, Antarctic.

ISSN:1208-6053    

DOI:10.1139/a00-001

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

This paper examines the ecological impacts arising from road networks and the potential ameliorating effects of roadside habitat in a highly modified landscape. A U.K. focus has been adopted to illustrate the effects of roads in a landscape with a long history of land use and intensive land management where the impacts and the potential for improvement are considerable. The impacts of roads in the ecological landscape include habitat loss, fragmentation, and degradation. These interrupt and modify natural processes altering community structures and in the longer term, population dynamics. The large number of fauna fatalities each year from road traffic accidents is also of concern. Road verges can however also provide habitat opportunities and restore connectivity in an otherwise fragmented landscape offering potential to offset some of the adverse impacts of the existing road network. This review demonstrates that roads can present both ecological costs and ecological benefits although currently there is insufficient evidence to confirm some of the key theories which relate to the impact of the barrier effects (at population level) or the value of road verges as ecological corridors. In the absence of complete information the full extent of the problems and opportunities cannot be gauged and every effort should be made therefore to enhance the habitat adjacent to existing roads and to constrain further fragmentation caused by the development of the existing road network. Where further construction is unavoidable conditions should be enforced to prevent roads from reducing further the remaining habitats of conservation value and the connectivity between such habitats.Key words: roads, wildlife, fragmentation, corridor, barrier, environmental impact.

ISSN:1208-6053    

DOI:10.1139/a00-003

出版商:NRC Research Press    

年代:1999

数据来源: NRC

摘要:

Flaring is an accepted practice in the oil and gas industry to dispose of waste gases in Alberta. However, incomplete combustion of these gases produces a variety of volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs). Public health concerns about gas flaring have existed for a number of years. Several facts are notable in attempting to understand what importance VOCs and PAHs from flare gas emissions have in contributing to adverse health effects in humans. Most flare stacks are located in rural areas. Current time-activity studies of humans are lacking in that they have not emphasized characterization of time-activity behavior of rural populations, who would be most susceptible to exposure from these pollutants. Available time-activity studies of primarily urban populations indicate that people spend a majority of time indoors. Numerous VOCs and PAHs measured in gas flare emissions are already present indoors, originating from indoor sources, and almost always at higher levels than outdoors. As humans inhale a majority of air indoors, inhalation exposure would be influenced to a much greater extent from being indoors than outdoors in these instances. Human health risk assessment of hazardous air pollutants emitted from burning flares must take into account indoor and other background exposures to provide useful information for public health decision-makers.Key words: flaring, air pollutants, exposure, hazardous

ISSN:1208-6053    

DOI:10.1139/a00-005

出版商:NRC Research Press    

年代:1999

数据来源: NRC

ISSN:1208-6053    

DOI:10.1139/a00-002

出版商:NRC Research Press    

年代:1999

数据来源: NRC