published_or_final_version / Chemistry / Master / Master of Philosophy

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No description available.

Hypotheses regarding the distribution, texture and trace element concentrations of lake sediments were tested by empirical analyses of multi-lake data sets (52 to 83 lakes). Sediment distribution was best characterized by the deposition boundary depth (DBD), the abrupt transition from coarse- to fine-grained sediments. The DBD can now be predicted from either empirical models or empirical-theoretical simplifications of wave of sediment threshold theory, both in terms of exposure (or fetch) and bottom slope. The texture (organic content, water content and bulk density) of profundal sediments was related to the inorganic sedimentation rate and exposure, but not to the lake trophic status or the net organic matter sedimentation rate. The relationships between sediment texture and intra- and inter-site variability, together with the models that predict the DBD and sediment texture, were used to develop an algorithm that should greatly reduce sampling effort in lake sediment surveys. Finally, sediment trace element concentrations were predicted from sediment texture, site depth and simple geologic classifications. The models developed here, provide a framework in which to sample lake sediments and interpret their properties.

About 25,000 acres of flax for fiber was grown during the second world war in the Province of Québec when the traditional sources of supply in Europe were cut off (Anonymous). With the armistice, the prices dropped and farmers abandoned this crop because of competition from European countries. In the 1950's a few farmers became interested in growing flax for linseed oil, chiefly in the Montreal area. The acreage bas increased steadily, so that by 1964 flax was being grown on about 35,000 acres in this Province (Shiller 1964). [...]

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A multichannel detection system based on a linear photodiode array (PDA) is described. The design and construction of the detection system and a rapid slew-scan computer-controlled stepping motor grating drive system is detailed. The theoretical performance of an optimized PDA system is contrasted with the performance of photomultiplier tubes. A technique is described which allows the dynamic range of the PDA to be extended by one order of magnitude towards higher light levels. A wavelength calibration procedure is outlined which results in a wavelength prediction accuracy of (+OR-)0.003 nm. A theory for high resolution spatial image positioning is presented and the ability to detect varying degrees of spectral overlap is evaluated. Applications of the PDA to the measurement and characterization of transient signals is described.

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