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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
321

Physical, chemical and geochemical factors influencing mercury accumulation in freshwater fish and humans in Ontario, Canada.

Richardson, G. Mark January 1994 (has links)
An empirical approach was taken to examine and test a variety of hypotheses that had been presented or postulated in the literature concerning mercury biogeochemistry in lakes. These hypotheses included: (1) mercury contamination in fish increases with increasing sulphate deposition; (2) mercury exposure in persons eating fish increases with increasing sulphate deposition; (3) mercury contamination in fish is unrelated to natural (non-anthropogenic) Hg sources. These hypotheses were all shown to be false for Ontario lakes, predominantly of the Canadian Shield. Also examined was the spatial association of lake water chemistry with sulphate deposition across Ontario. It was determined that morphometric characteristics of the lakes, as well as watershed buffering capacity, together explained more of the spatial variation in lake water chemistry than did patterns of sulphate deposition across the province. Once these confounding influences were removed, the water chemistry variables most closely reflecting patterns of sulphate deposition were dissolved organic carbon (DOC) and sulphate ion concentration ( (SO$\sb4\sp{2-}$)), not pH or alkalinity. Aluminum ion concentration ( (Al$\sp-$)), which is postulated to increase in lakes as a result of acidic deposition, had no discernible relationship to sulphate deposition. Based on the results of empirical analyses, including path analysis (causal modelling), a complex hypothesis explaining the interrelationships of precipitation, water chemistry, geochemistry, and fish mercury contamination was postulated. Of particular note concerning this model were the following: (1) fish mercury and human mercury exposure decrease as sulphate deposition increases; (2) DOC, not pH or alkalinity, is the water chemistry variable most significantly related to sulphate deposition; (3) DOC, not pH, is the water chemistry variable most significantly associated with fish mercury contamination; (4) causal modelling provided empirical evidence supporting the simultaneous influence of 3 different mechanisms postulated in the literature to control or influence mercury accumulation in freshwater fish.
322

Environmental and biological correlates of maternal investement in red squirrels

Studd, Emily January 2013 (has links)
No description available.
323

Niche construction, facilitation and their ecological and evolutionary consequences

Kylafis, Grigorios January 2011 (has links)
No description available.
324

Community and ecosystem-level interactions between mussel beds and their associated organisms

Largaespada Roque, Cesar January 2010 (has links)
No description available.
325

The balance between selection and gene flow evaluated in threespine stickleback

Muttalib, Shahin January 2012 (has links)
No description available.
326

Validation and integration in spread models of influenza: scientific insights and policy implications during influenza epidemics/pandemics

Hyder, Ayaz January 2012 (has links)
No description available.
327

Reproductive and endocrine health of Tree Swallows (Tachycineta bicolor) exposed to historical and current-use flame retardant chemicals in wastewater treatment plant effluent

Gilchrist, Tiffany January 2012 (has links)
No description available.
328

Emissions from land-cover change in Panama: uncertainty, dynamics, and perceptions

Pelletier, Johanne January 2012 (has links)
No description available.
329

Ecological impacts of invasive trout in Patagonian lakes

Correa-Guzman, Cristián January 2012 (has links)
No description available.
330

Hypoxia, carotenoids, and colour expression in the widespread African cichlid fish Pseudocrenilabrus multicolor victoriae

McNeil, Georgia January 2012 (has links)
No description available.

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