Dept of Earth & Environmental Sciences
Centre for Environmental and Information Technology (EIT)
200 University Ave. W
Waterloo, Ontario, Canada N2L 3G1
Phone: (519) 888-4567
Using solid speciation to understand the complicated legacy of arsenic contamination near Yellowknife, NWT
Dr. Heather E. Jamieson, Queens University
Everyone welcome! Reception to follow in the EIT foyer.
Two large, long-lived gold mines that operated before many environmental regulations were established have left a complicated environmental legacy near the City of Yellowknife. Arsenic is naturally associated with this type of ore deposit, and the choices made regarding ore processing and waste management during operation contributed to widespread contamination that is still a serious concern in the community. For the past 21 years, our research group has investigated tailings, water, soils, lake sediments, and windblown dust to provide information essential to risk assessment and remediation design. A critical part of our research has been characterizing the solid host of arsenic, and we have found that synchrotron-based microanalysis and automated mineralogy have been powerful tools, particularly when used together. Our early work showed that an important host for arsenic in the tailings at Giant is the roaster-generated iron oxide phase. This differed from the previous-held view that all the arsenic in the tailings was sulphide-hosted. The maghemite contains several weight per cent of both As(III) and As(V) in ratios that are consistent for long-exposed tailings and recently deposited, indicated stable sequestration of both species. Investigation of the near-surface soils has revealed the persistence of arsenic trioxide from stack emissions. Micro-XRD and As micro-XANES were critical in discovering this contamination, which had been overlooked in the original remediation plan. We are currently conducting solid state speciation in hundreds of regional soil samples to distinguish natural from anthropogenic arsenic using automated mineralogy to characterize thousands of arsenic-bearing particles in each sample. Clean-up criteria and strategies for these soils are being reconsidered. We have also recognized arsenic trioxide in lake sediments where post-depositional biogeochemical processes have partially transformed it to arsenic sulphide. Finally, the primary arsenic host in windblown dust has been identified as roaster-generated iron oxide, and fortunately arsenic trioxide is not present.
Heather E. Jamieson’s expertise is in the area of environmental geochemistry, particularly the mineralogical controls on the mobility and bioaccessibility of metals and metalloids such as arsenic, antimony, rare earth elements and lead in mine waste. She has pioneered the application of synchrotron-based X-ray experiments and other microanalytical methods to metal speciation in mine tailings, soils and sediments. Dr. Jamieson was awarded the 2017 Peacock Medal from the Mineralogical Association of Canada which is given to a scientist who has made outstanding contributions to the mineral sciences in Canada. Much of her fieldwork is in the Canadian North but she has also conducted research in Nova Scotia, Chile, Peru, USA, Spain and Australia. She supervised more than 50 graduate students, most of whom are now working as environmental consultants or regulators. She has coedited and contributed a chapter to the Reviews in Mineralogy and Geochemistry Volume 79: Arsenic: Environmental Geochemistry, Mineralogy and Microbiology.
The Adrian Smith Lecture Series
The Adrian Smith Lecture Series on Environmental Geochemistry, an annual lecture in environmental geochemistry, was established in the Department of Earth and Environmental Sciences at the University of Waterloo by colleagues and friends in memory of Dr. Adrian Smith.
For more than a decade Adrian Smith was a regular visitor to our department, initially as guest speaker and later as an adjunct faculty member, a colleague and a supervisor to our students. Adrian generously gave his time, participating in technical discussions of thesis projects, providing comments and advice for improvements and fostering philosophical debates. These efforts are reflected in new approaches and attitudes that our students take toward research and science.