CFRAW Background
Below, you can read about past oil sands land reclamation research and the rationale behind the CFRAW Project.
Oil Sands Land Reclamation
In accordance to Alberta's reclamation standards, companies must remediate and reclaim any land used in oil sands development, such that it is able to support a range of activities similar to its previous use. The Alberta Sustainable Development Plan for the Athabasca Region identifies progress towards attainment of natural conditions on reclaimed habitats as being a top priority (Alberta Environment 1999). One of the greatest challenges involved in addressing progress towards a ‘natural’ state is to identify biological endpoints that reflect achievement of ecological health given the specific environmental conditions of an area. Aquatic habitats vary enormously in physico-chemical characteristics, depending on microtopography, drainage characteristics, loadings of nutrients, and disturbance history. This markedly influences the type of climax community to be expected.
Wetlands are proposed to make up 20-40% of the final reclamation landscape that will be left after the completion
of oil sands mining of approximately 1,200 km2 of land northeast of Fort McMurray. The current situation of the CFRAW group puts us in an excellent position to provide guidance to the mining companies regarding the theoretical structure and design
of the landscape network.
Previous Oil Sands Research and CFRAW Project Rationale
Benthic invertebrates (midges and related species) form an integral link in food webs of aquatic and terrestrial ecosystems. They transform the biomass produced by plants and microbes (organic carbon) into living material that supports many of the top predators (fish and wildlife). Ongoing collaborative work in aquatic habitats of the Fort McMurray region (marshlands, ponds, ditches, lakes, reservoirs - henceforth called ‘wetlands’) has emphasized the close linkage between aquatic invertebrate attributes (richness, abundance, production), the aquatic macrophyte communities that provide habitat structure for the benthos, and the health of associated avifauna, fishes and amphibians. Based on recent work completed by university researchers in partnership with the oil sands industry, we now know that constructed wetlands will sustain biota comprising a viable food web. Prevailing evidence suggests at least a trend towards convergence of constructed wetland communities to a ‘natural condition’ goal - wetlands that are productive, diverse, and sustainable.
Various strategies are being evaluated by the mining companies to facilitate wetland construction and speed the naturalization process, at very significant cost. The reclaimed landscapes must be biologically viable, productive, sustainable, and the reclamation methods proposed to accelerate maturation processes must make the most economical use possible of limited resources (stockpiled materials, use of land area, construction and monitoring costs, etc.). Energy flow through the biota must sustain the type of ecosystem desired and mandated by Alberta Environment’s mining approval permits.
Both natural (opportunistic) and constructed wetlands have formed on lease areas since the oil sands companies began preparing to mine bitumen in the 1970's. The present landscape is dotted with aquatic systems varying in age, characteristics, and amount of organic matter in their sediments. Preliminary research suggested that community development in young wetlands (< 7 years old) may be limited by heterotrophic processes. Supplies of nutrients and substrate suitability, together with residual toxicity likely limit rates of primary production (Fig. 1).
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Fig. 1. Hypothetical path analysis of factors regulating zoobenthic community succession, ultimately transmitted up the food chain. Width of arrows indicates degree of importance. Red: negative effect imposed in the direction of the arrow. Green: positive effect. Tailings and mine water-amended wetlands are rich in bitumen and dissolved organic carbon in the form of
naphthenic acids. They are also alkaline and saline. The high clay content of sediments is not conducive to macrophyte
establishment. Naphthenic acids are initially toxic to zoobenthos and inhibit colonization. Toxicity declines as a consequence
of photolysis and microbial action. Algal growth is stimulated by the DOC, which forms an active biofilm on the substrate.
Macrophyte development is inhibited by turbidity, salinity, drying, and substrate texture but facilitated by benthic organic matter
accumulation. Zoobenthos benefit from both benthic organic matter and macrophytes, which provide habitat and a substrate
for microbial development. Zoobenthos graze on microbes rather than directly on detritus. Decaying plants contribute to the
benthic organic matter pool in a wetland. However, in the short term, decomposition reduces the mass of litterfall. Over time,
partly decomposed plant parts result in the accumulation of the thick peat layer that characterizes fens and bogs.
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In older wetlands (< 7 years old), energy flow and food chain length may be limited by the type of carbon base and the degree of macrophytic development. Peatlands form when plant growth and the input of detritus exceed the needs of the biota or the capacity of microbes to process the material during a short summer season. This results in a nutrient-limited, diverse ecosystem. Disturbed systems tend to have fewer but very abundant species, inefficient energy transfer, and short food chains that support fewer desirable fish and wildlife.
The CFRAW Project will assess several classes of wetland differing in reclamation type (reference vs. soft-tails amended), age (young vs. older), and organic base (poor vs. rich; vegetative materials vs. hydrocarbon-derived materials). Doing so will allow the CFRAW group to predict the types of biological communities that should develop in these water bodies, and how much time these communities require to reach a 'natural' state. This knowledge will help CFRAW's industrial partners utilize the most effective reclamation strategies for developing viable wetland systems.
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