麻豆传媒

B. Sc. Honours Thesis

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Elevated levels of 238Uranium (U) and its daughter products 226Radium (Ra) and 222Radon (Rn) in groundwater, surface water, and soils have the potential of posing health risks. In particular, high levels of radioactive elements in water or soil may correlate with high Rn in indoor air, which is considered by some to be carcinogenic. The purpose of this thesis was to determine whether U, Ra, and Rn data from 1978 to 1981 mining exploration activities in Nova Scotia could be used to predict the potential occurrence of elevated Rn in indoor air. To this effect, the writer compiled and entered almost 5000 data points onto maps at a scale of 1:50 000, and generated the accompanying database, from exploration assessment report maps filed at the Nova Scotia Department of Natural Resources. The data have been integrated into 12 basic GIS (U, Ra, and Rn) geochemistry layers. These data have been spatially analyzed against previously existing digital data, using ArcView sofiware. Preexisting layers used include: geographic features, geology, faults, and unconformities, all available at a scale of 1:500 000.

Data synthesized using GIS allowed examination of a variety of combinations of data layers. Analyses performed included the generation of graphs, tables, queries, "contained in" operations, and "distance to" equations, as well as the synthesis of map data. Results indicate that although the study area typically has relatively low U values, Rn and Ra values can be considered elevated in some locations. In particular, this study confirms that there are areas of Nova Scotia where the risk of elevated levels of Rn in indoor air could exist, which were not widely recognized until now. These areas include the Panuke Road area, underlain by Horton Group sedimentary rocks, and the Rawdon Hills area, underlain by the Halifax Group. The results also suggest that the scale of the available digital data is critical in determining the level to which the data can be analyzed, and a limiting factor in the analysis was the generalized scale (< 1:50 000) of much of the preexisting layers. Despite this limitation, the advantages of the GIS approach in the exploitation and analysis, of otherwise relatively unmanageable mineral exploration data, for environmental purposes are obvious. The data from this thesis are being used to update existing maps of Rn and U potential for the Nova Scotia Department of Environment.

Keywords:
Pages: 305
Supervisor: Marcos Zentilli

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Awards

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CIM Student Essay Award (Undergraduate), (Environment)