Natural and Constructed Wetlands for Pollution Remediation

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Canada’s position as a global supplier of natural resources is challenged by the lack of sustainable and cost effective solutions to deal with the large scale water contamination associated with hydrocarbon extraction (fracking, oil sands), mining and industrial, agricultural and municipal waste water releases. The proposed research investigates the application of natural and constructed (also referred to as engineered or treatment) wetlands to treat large scale water contamination. The specific goal of this research is to investigate the ability of wetlands, either constructed or natural, to remove contaminants from waste waters in an efficient and environmentally safe manner under Canadian specific climate conditions and design specifications. The research includes the development and experimental testing of a quantitative, mathematical mass balance model of the environmental fate and toxicological effects of contaminants associated with bitumen and metal extraction in wetlands. The model will describe the effect of various wetlands design characteristics (e.g. size, water flow characteristics, vegetation cover) and environmental conditions (e.g. temperature) on the efficiency of chemical removal from inflowing waste waters. The model will also be able to assess contaminant concentrations in wetland flora and fauna over time and determine whether wetland treatment is environmentally safe by comparing concentrations to threshold values for toxicity. This model will build on our previous work on models of the fate of contaminants in aquatic systems. As part of this study, the performance of the model will be experimentally tested in small scale laboratory housed constructed wetlands at SFU’s Alcan Aquatic Research Center. Opportunities for further field testing will be sought out through other means. The research also includes the development of methods for the measurement and estimation of the rates of chemical removal through (bio) transformation and partitioning in sediments, soils and vegetation of wetlands. Both transformation and partitioning are key processes in the environmental fate of contaminants in wetlands and remain difficult to predict. To do this, we plan to further develop and apply our thin-film sorbent dosing methods for simultaneous measurement of transformation rates and unbound chemical fractions. This method provides a suitable and promising method for making measurements of both transformation rates and partition coefficients in vegetation, sediment, soil and water that are useful in the wetland mass balance model. Finally, the results of the research will be applied to propose wetland treatment design scenarios that are feasible in Canada and effective and environmentally safe. The models will also be applied to explore the response of natural wetlands to long term contaminant inputs associated with resource extraction practices in Canada. The research aims to fill an apparent and recognized gap in this green technology in Canada by training and supporting a new generation of environmental consultants, engineers and scientists who can apply and further develop this technology in Canada and other countries. The proposed research takes advantage of our internationally recognized expertise in modeling the environmental fate and effects of chemical contaminants in aquatic and terrestrial ecosystems as well as our expertise in measuring and modeling the effect of biological transformation on chemical fate in sediments and chemical bioaccumulation in aquatic and terrestrial food-webs.