The Liber Team
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Affiliation: University of Saskatchewan, Toxicology Centre
Principal Investigator: Dr. Karsten Liber
Research Associate: None at present
Current Graduate Students: Naveen Puttaswamy (Ph.D. Candidate); Navdeep Toor (Ph.D. Candidate)
Team Role: The Liber team is analyzing and documenting partitioning of trace metal concentrations in water and sediments, tracking and assessing toxicity of water from experimental trenches and focal wetlands using lab cultured zooplankton. They are also investigating the role of salinity in aquatic toxicity, its influences on toxicity of other chemical stressors, and how these relationships change over time and influence wetland succession (in collaboration with the University of Waterloo).
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Current Graduate Students
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- Naveen Puttaswamy (Ph.D. In Progress)
- Started: 2005
- Thesis Title: Evaluation of metal releases from oil sands coke: an assessment of ecotoxicological hazard and risk to aquatic organisms.
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Project Summary: Provincial legislation in Alberta mandates the reclamation of all land affected by oil sands mining. As part of their reclaimation strategy, the oil sands industry is examining the use of coke (a byproduct of oil distillation) to stabilize clay-dominated mine tailings in constructed wetlands. Heavy metals released from oil sands coke may become bioavailable for uptake in aquatic organisms and lead to bioaccumulation. It is therefore important to understand the fate and toxicity of metals released from coke in order to undertake the most biologically productive wetland reclamation strategies.
Using Ceriodaphnia dubia as a model species, Naveen is examining whether age or the weathering of oil sands coke influences heavy metal release and toxicity. He is also testing which metals cause toxicity in coke leachate.
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- Navdeep Toor (Ph.D. In Progress)
- Started: 2005
- Thesis Title: Persistence and Toxicity of Naphthenic Acids in Oil Sands Process-Affected Waters and Commercial Mixtures: Understanding Wetland Bioremediation.
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Project Summary: The alkaline hot water extraction process used to separate bitumen from sand produces tailings and oil sands process affected waters (OSPWs). The toxicity of these OSPWs has been shown to be at least partially related to elevated levels (50-120 mg/L) of a relatively persistent group of dissolved organic acids known as naphthenic acids.
Using laboratory microcosms to mimic natural wetland environments, Navdeep is evaluating the potential for degrading oil sands process material, leading to a reduction in aquatic toxicity of OSPWs. Ultimately, this will allow planners and regulators to better understand the effectiveness of remediating OSPWs to meet various performance-based and regulatory requirements (e.g., thresholds for naphthenic acid toxicity to aquatic biota). Navdeep's work will also provide information needed to help design criteria for evaluating a wetland’s remediation success, including OSPW loading rates, residence times, and the conditions required by microbes for their successful colonization and proliferation.
Past Graduate Students
and Postdoctoral Fellows
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- Dominique Turcotte, Ph.D.
- Completed: 2010
- Project: Interactive effects of salinity and naphthenic acids on toxicity of oil sands process water to freshwater invertebrates.
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Project Summary: The oil sands mining industry in the Athabasca River area, uses large quantities of water during the oil extraction process. The resulting oil sands process water (OSPW) is proposed to be part of future reclamation landscapes, so understanding its toxicity to freshwater aquatic invertebrates is important in order to develop environmentally acceptable OSPW reclamation plans. OSPW typically contains elevated concentrations of salts and naphthenic acids (NAs), but low levels of other contaminants such as PAHs and metals. Variations in ionic composition have been demonstrated to influence sub-lethal effects of salinity on some invertebrate species. Ions also have the potential to interact with and alter the toxicity of various contaminants. Therefore salinity may play an important role in the toxicity of OSPW on fresh¬water invertebrates. The nature of the toxic interaction between major ions and naphthenic acids has not yet been researched and it could be a significant factor when considering the total toxicity of the OSPW on long term reclamation.
Dominique’s work investigates the toxicity of OSPW salinity on freshwater biota. She aims to determine whether or not the combined concentrations of major ions affect the toxicity of the resulting salinity, and to determine possible interactions between naphthenic acids and salinity.
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- Allison Squires (M.Sc.)
- Completed: 2005
- Thesis Title: Ecotoxicological assessment of using coke in aquatic reclamation strategies at the Alberta oil sands. [PDF]
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Thesis Abstract: Oil sands, also known as tar sands or bituminous sands, are sand deposits impregnated with dense, viscous petroleum called bitumen. The two major oil sand mining companies currently producing synthetic crude oil in the province of Alberta are Syncrude Canada Ltd. and Suncor Energy Inc. Coke is a waste product formed during the heavy oil upgrading processes. The amount of coke produced currently at the Syncrude and Suncor operations is significantly more than what can be combusted and/or sold. Therefore, it must be stored on site making coke a necessary component of future reclamation landscapes. It is as yet unclear whether or not coke poses a significant toxicological risk (i.e. through leaching of constituent chemicals and elements) to the aquatic or terrestrial environments if used in a long-term reclamation capacity. The primary objective of this research was to evaluate whether stockpiled Syncrude Canada Ltd. and Suncor Energy Inc. coke can safely and effectively be used as a substrate amendment in an aquatic reclamation option.
Syncrude and Suncor coke were exposed to three different sets of water quality conditions: high and low dissolved oxygen, pH (5, 7.5 and 10) and freeze-thaw cycles. These conditions have the potential to affect the leaching of constituents from coke once placed in an aquatic environment in northern Alberta. Metals were observed to leach from both coke types under all treatments. Some of these metals (cobalt, copper, manganese, molybdenum, nickel, vanadium and zinc) reached levels of toxicological interest by exceeding published LC50 values for the aquatic macroinvertebrate Chironomus sp. and/or established Canadian Water Quality Guidelines for the protection of aquatic life.
To determine the source of metals observed to leach in the leaching experiments, an accelerated weathering experiment was conducted. Coke from both Syncrude and Suncor were pre-treated by rinsing with water to remove any natural soil or sediment particles that become associated with the coke during storage, and with peroxide to remove any metals bound to the surface of the coke. It was concluded that the metals leaching into the overlying water and pore water of the coke were from either the natural soil/sediment particles, and/or were weakly bound to the surface of the coke. Rinsing coke with water before adding it as a substrate amendment in an aquatic reclamation strategy may decrease its potential toxicity to aquatic organisms by removing the soil/sediment debris and metals loosely bound to the surface of the coke, reducing initial amounts of metals available to the organisms in the pore and overlying waters.
As part of these leaching experiments, coke from both Syncrude and Suncor were further characterized with elemental analysis and qualitative analysis with polarized light microscopy and scanning electron microscopy. These analyses showed distinct differences in the physical properties (i.e. particle size and structure) of Syncrude and Suncor coke. However there appeared to be little variation in the elemental and structural composition among the different weathering treatments within each coke type.
Following leaching, coke from Syncrude and Suncor was used as a substrate in 10-d toxicity tests with Chironomus tentans. These experiments evaluated whether the leachate generated from coke, or the coke itself, caused of an adverse effect on the survival and/or growth of this aquatic invertebrate. Decreased survival and growth of C. tentans was observed when Suncor coke was used as a substrate. However, further experimentation showed that these effects were due to the physical properties of Suncor coke, rather than any constituents that leached from the coke.
In a separate experiment, combinations of fresh oil sands waste materials were added to experimental enclosures constructed at Syncrude Canada Ltd in May 2002. Core samples of these waste materials were collected after aging in situ for periods of 2 and 14 months. The aged samples along with fresh (0 month) samples, were used as substrate material in 10-d toxicity tests with C. tentans to assess the potential toxicity of both fresh and field-aged combinations of waste materials. These experiments found that there is a potential for greater initial stress or toxicity to aquatic organisms when the substrates are freshly added to the reclaimed wetlands. However, this initial potential toxicity of oil sands waste materials can decrease with aging in an aquatic environment.
Current and Past Undergraduate Student Projects
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- Pola Wojnarowicz (B.Sc. - Honours in Toxicology)
- Completed: 2009
- Thesis Title: Effects of Salt Interactions in Oil Sands Process Waters on Ceriodaphnia dubia using an Isobolographic Approach. [PDF]
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