Factors affecting the occurrence, isomer ratio and enantioselective degradation of hexachlorocyclohexane in arctic and temperate aquatic systems
grantor: University of Toronto An investigation to determine factors affecting the biodegradative losses of HCHs in arctic, subarctic and temperate aquatic systems was performed. Concentrations of Ã- and ã-HCH were highest in large and cold lakes and lowest in warmer temperate lakes. The Ã-HCH/ã-HCH...
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| Format: | Thesis |
| Language: | English |
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2000
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| Online Access: | http://hdl.handle.net/1807/13930 http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0022/MQ50398.pdf |
| Summary: | grantor: University of Toronto An investigation to determine factors affecting the biodegradative losses of HCHs in arctic, subarctic and temperate aquatic systems was performed. Concentrations of Ã- and ã-HCH were highest in large and cold lakes and lowest in warmer temperate lakes. The Ã-HCH/ã-HCH ratio was highest in arctic/subarctic lakes, indicating long range transport and the low ratios in small temperate systems are due to fresh ã-HCH. The enantiomer ratio (ER), was lowest in lakes with high concentrations of Ã-HCH, in cold and/or oligotrophic lakes with long residence times. ERs were highest in small temperate lakes with low Ã-HCH concentrations. These factors are significantly related to the contact between Ã-HCH and oligotrophic microbes. Enantioselective degradation was also greatest in wetlands and northern streams due to contact with the biofilm. Microcosms were unable to isolate factors enhancing enantioselective degradation of Ã-HCH due to the inability to mimic the conditions for the degrading microbes. M.Sc. |
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