Fate of contaminants in groundwater and development of passive remediation systems

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The release of contaminants from legacy anthropogenic activities has resulted in large-scale contamination of groundwater, soils and sediments at many locations in Canada and around the world. As an example, mining and manufacturing activities have led to the release of toxic elements, including As, Cd, Co, Cu, Mo, Ni, Pb, Hg, Zn, and V that have now caused degradation of water quality or have accumulated in soils and sediments downstream from source areas. Due to the scale of the contamination, costly controls are required to minimize further degradation of water supplies and affected ecosystems. A number of approaches have been developed for remediating groundwater, sediment and soils and advances have been made over the past several decades. In situ remediation techniques are generally applied at contaminated sites that are less than several km2 in scale. Implementing remediation approaches at larger scales presents greater challenges due to limitations to site access and high costs for reagents. My recent research acitivities have focused on identifying low cost approaches for stabilizing contaminants that can be applied at the watershed scale. Projects we are conducting include studies to 1) understand the cycling of Hg and processes controlling Hg methylation in a dynamic watershed, 2) understand the fate of emerging contaminants, including explosives, pharmaceutical compounds, artificial sweeteners, and perfluorinated compounds in surface water, wastewater and groundwater, and 3) understand the fractionation of stable isotopes of Cr, Se, Cu, Zn and Ni as tools for delineating reaction mechanisms and reaction progress. We have evaluated new methods for stabilizing or treating contaminants in groundwater, waste materials and soils. I utilize a series of instruments, including a trace Hg analyzer, an automated methyl Hg analyzer, and ion chromatographs, a gas chromatograph, and a new high-performance liquid chromatograph/electrospray triple quadrupole mass spectrometer. I also have access to a multi-collector inductively coupled plasma mass spectrometer through collaboration. We have applied novel synchrotron techniques to further understand reaction mechanisms. During the next five years, I plan to accelerate my research activities to assess remediation strategies that can be applied to large-scale contaminated sites. I will conduct laboratory studies to evaluate the application of reactive media as co-blending reagents to stabilize metals in contaminated soils and sediments. I will study the fate of emerging contaminants in the subsurface and identify sustainable treatment approaches. I will continue to develop novel tools to characterize the effectiveness of remediation systems. The overall goal is to work towards improving the environment in a practical, cost-effective and technically sound manner.