937 resultados para fine default


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This investigation of geochemistry and mineralogy of heavy metals in fine grained (<63^m) sediment of the Welland River was imdertaken to: 1) describe metal dispersion patterns relative to a source, identify minerals forming and existing at the outfall region and relate sediment particle size to chemistry; 2) to delineate sample handling, preparation and evaluate, modify and develop analytical methods for heavy metal analysis of complex environmental samples. Ajoint project between Brock University and Geoscience Laboratories was initiated to test a contaminated site of the Welland River at the base of Atlas Speciality Steels Co. Methods were developed and utilized for particle size separation and two acid extraction techniques: 1) Partial extraction; 2) Total extraction. The mineralogical assessment identified calcite, dolomite, quartz and clays. These minerals are typical of the carbonate-shale rock basement of the Niagara Peninsula. Minerals such as, mullite and ferrocolumbite were found at the outfall region. These are not typical of the local geology and are generally associated with industrial pollutants. Partial and total extraction techniques were used to characterize the sediments based on chemical distribution, elemental behaviour and analytical differences. The majority of elements were lower in concentration in the partial extraction technique; suggesting these elements are bound in an acid extractable phase (exchangeable, organic and carbonate phases). The total extraction technique yielded higher elemental concentrations taking difficult oxides and silicates into solution. Geochemical analyses of grain size separates revealed that heavy metal (Co, Ni, V, Mn, Fe, Ba) concentrations did not increase with decreasing grain size. This is a function of the anthropogenic mill scale input into the river. The background elements (Sc, Y, Sr, Mg, Al and Ti) showed an increase in concentration to the finest grain size suggesting that it is directly related to the local mineralogy and geology. Dispersion patterns ofmetals fall into two distinct categories: 1) the heavy metals (Co, Cu, Ni, Zn, V and Cr), and 2) the background elements (Be, Sc, Y, Sr, Al and Ti). The heavy metals show a marked increase in the outfall region, while the background elements show a significant decrease at the outfall. This pattern is attributed to a "dilution effect" ofthe natural sediments by the anthropogenic mill scale sediments. Multivariant statistical analysis and correlation coefficient matrix results clearly support these results and conclusions. These results indicate the outfall region ofthe Welland River is highly contaminated with to heavy metals from the industrialized area of Welland. A short distance downstream, the metal concentrations return to baseline geochemical levels. It appears, contaminants rapidly come out of suspension and are deposited in close proximity to the source. Therefore, it is likely that dredging the sediment from the river may cause resuspension of contaminated sediments, but may not distribute the sediment as far as initially anticipated.

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This thesis aims to uncover the dynamics, causes and outcomes of women's reliance on unregulated home-based child care in Ontario, Canada, and the implications ofthis form of care for women's equality. Drawing on a longitudinal qualitative study, I examine the diverse experience of 14 women using home-based child care and engaged in both paid work/training and care work for children under the age of six, and draw comparisons with users of other forms of child care. I argue that home-based child care involves high levels of instability for continuity of care and is chosen largely as a default position based on economic considerations. It represents a compromise between the demands of social reproduction and paid work/training that entangles mothers in relations of exploitation with care providers. Doing so leaves both mothers and care providers socially and economically vulnerable and relying on social networks to fill in the gaps.

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Architectural rendering for Moulton Hall, Chapman College, Orange, California. Completed in 1975 (2 floors, 44,592 sq.ft.), this building is named in memory of an artist and patroness of the arts, Nellie Gail Moulton. Within this structure are the departments of Art, Communications, and Theatre/Dance as well as the Guggenheim Gallery and Waltmar Theatre.

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Architectural model of Moulton Hall Fine Arts Complex, Chapman College, Orange, California. Completed in 1975 (2 floors, 44,592 sq.ft.), this building is named in memory of an artist and patroness of the arts, Nellie Gail Moulton. Within this structure are the departments of Art, Communications, and Theatre/Dance as well as the Guggenheim Gallery and Waltmar Theatre. Model photographed by Rene Laursen, Santa Ana, California.