No description available.

The inadvertent ingestion of contaminated soil is the dominant exposure route of non-volatile and semi-volatile contaminants such as polycyclic aromatic hydrocarbons (PAHs). Quantitative mass balance soil ingestion studies have been used to determine soil ingestion rates for use in human health risk assessments (HHRA) that can be used to predict the likelihood of adverse effects in individuals exposed to hazardous contaminants such as PAHs in contaminated soil. The Cold Lake region of Alberta is one of the three major oil sands regions of Alberta, and PAH concentrations in this oil sand region may be elevated in the atmosphere and the soil, resulting in increased exposures to PAHs. The area is home to Cold Lake First Nation who practice traditional activities and lifestyles that may put them in greater contact with soil than previous soil ingestion studies suggest. The primary objective of this research was to assess the soil ingestion rate in a group of First Nations subjects inhabiting the Cold lake region, and assess the carcinogenic risk posed by exposures to PAHs in air and soil. The study employed a quantitative mass balance tracer approach to estimate soil ingestion rates, and followed 9 subjects over a 13 day period. Soil and air samples were simultaneously collected to assess PAH contamination. The mean soil ingestion rate using Al and Si elemental tracers was 52 mg d-1, with a 90th percentile of 220 mg d-1, and a median soil ingestion rate of 37 mg d-1. These values are greater than the soil ingestion rates for HHRA recommended by Health Canada. The mean increase in excess lifetime cancer risk posed by inadvertent ingestion of soil to a First Nations’ individuals following traditional activities was 0.02 cases per 100,000 people with a 95% risk level of 0.067 cases per 100,000 people. Exposure to PAHs through inhalation posed a maximum lifetime cancer risk below 0.1 cases per 100,000, people. Thus, this study found no appreciable increase in excess lifetime associated with PAH exposure of First Nations’ people in the Cold Lake region.

The inadvertent ingestion of contaminated soil is the dominant exposure route of non-volatile and semi-volatile contaminants such as polycyclic aromatic hydrocarbons (PAHs). Quantitative mass balance soil ingestion studies have been used to determine soil ingestion rates for use in human health risk assessments (HHRA) that can be used to predict the likelihood of adverse effects in individuals exposed to hazardous contaminants such as PAHs in contaminated soil. The Cold Lake region of Alberta is one of the three major oil sands regions of Alberta, and PAH concentrations in this oil sand region may be elevated in the atmosphere and the soil, resulting in increased exposures to PAHs. The area is home to Cold Lake First Nation who practice traditional activities and lifestyles that may put them in greater contact with soil than previous soil ingestion studies suggest. The primary objective of this research was to assess the soil ingestion rate in a group of First Nations subjects inhabiting the Cold lake region, and assess the carcinogenic risk posed by exposures to PAHs in air and soil. The study employed a quantitative mass balance tracer approach to estimate soil ingestion rates, and followed 9 subjects over a 13 day period. Soil and air samples were simultaneously collected to assess PAH contamination. The mean soil ingestion rate using Al and Si elemental tracers was 52 mg d-1, with a 90th percentile of 220 mg d-1, and a median soil ingestion rate of 37 mg d-1. These values are greater than the soil ingestion rates for HHRA recommended by Health Canada. The mean increase in excess lifetime cancer risk posed by inadvertent ingestion of soil to a First Nations’ individuals following traditional activities was 0.02 cases per 100,000 people with a 95% risk level of 0.067 cases per 100,000 people. Exposure to PAHs through inhalation posed a maximum lifetime cancer risk below 0.1 cases per 100,000, people. Thus, this study found no appreciable increase in excess lifetime associated with PAH exposure of First Nations’ people in the Cold Lake region.

No description available.

A study was conducted to evaluate the properties and processes influencing the rate and magnitude of volume decrease and strength gain for oil sand fine tailings resulting from a change in bitumen extraction process (caustic versus non-caustic) and the effect of adding a coagulant to caustic fine tailings. Laboratory flume deposition tests were carried out with the objective to hydraulically deposit oil sand tailings and compare the effects of extraction processes on the nature of beach deposits in terms of geometry, particle size distribution, and density. A good correlation exists between flume deposition tests results using oil sand tailings and the various other tailings materials. These comparisons show the reliability and effectiveness of flume deposition tests in terms of establishing general relationships and can serve as a guide to predict beach slopes. Fine tailings were collected from the various flume tests and a comprehensive description of physical and chemical characteristics of the different fine tailings was carried out. The characteristics of the fine tailings is presented in terms of index properties, mineralogy, specific surface area, water chemistry, liquid limits, particle size distribution and structure. The influence of these fundamental properties on the compressibility, hydraulic conductivity and shear strength properties of the fine tailings was assessed. Fourteen two meter and one meter high standpipe tests were instrumented to monitor the rate and magnitude of self-weight consolidation of the different fine tailings materials. Consolidation tests using slurry consolidometers were carried out to determine consolidation properties, namely compressibility and hydraulic conductivity, as well as the effect of adding a coagulant (calcium sulphate [CaSO4]) to caustic fine tailings. The thixotropic strength of the fine tailings was examined by measuring shear strength over time using a vane shear apparatus. A difference in water chemistry during bitumen extraction was concluded to be the cause of substantial differences in particle size distributions and degree of dispersion of the comparable caustic and non-caustic fine tailings. The degree of dispersion was consistent with predictions for dispersed clays established by the sodium adsorption ratio (SAR) values for these materials. The biggest advantage of non-caustic fine tailings and treating caustic fine tailings with coagulant is an increased initial settlement rate and slightly increased hydraulic conductivity at higher void ratios. Thereafter, compressibility and hydraulic conductivity are governed by effective stress. The chemical characteristics of fine tailings (water chemistry, degree of dispersion) do not have a significant impact on their compressibility behaviour and have only a small influence at high void ratio (low effective stress). Fine tailings from a caustic based extraction process had relatively higher shear strengths than comparable non-caustic fine tailings at equivalent void ratios. However, shear strength differences were small and the overall impact on consolidation behaviour, which also depends on compressibility and hydraulic conductivity, is not expected to be significant.

No description available.