Tracking toxic pollutants

By Mike Foster

From 1948 to 2004, seven million ounces of gold were extracted from the Giant Mine on the edge of Great Slave Lake in the Northwest Territories. However, these vast riches had a deadly by-product: 237,000 tonnes of arsenic trioxide.

Ten years ago this month, the governments of Canada and of the Northwest Territories (NWT) signed an agreement to clean up the site. The Giant Mine Remediation Project, which aims to make surrounding land and water safe and to restore the landscape, is expected to cost nearly $1B. The site, located only six kilometers from Yellowknife, includes 100 highly contaminated buildings, open pits, tailing ponds and contaminated soil.

University of Ottawa professor Laurie Chan, who holds a Canada Research Chair in toxicology and environmental health, is a member of the Independent Peer Review Panel established by Aboriginal Affairs and Northern Development Canada to review aspects of the Giant Mine clean-up. Last August, he was involved in choosing the best of 56 options for treating the site, eventually selecting the Frozen Block Method to freeze the arsenic trioxide that is currently buried in underground containers. This process relies on refrigeration processes similar to those used by hockey arenas to keep the man-made toxins from seeping into the surrounding environment.

“It would be too difficult and dangerous to remove it. It would be like mining for arsenic,” said Chan, who continues to advise the remediation project on occupational health and safety measures. The project also monitors contaminant levels in fish, such as Arctic grayling, in Baker Creek, which is a popular fishing spot that runs through the site.

In a similar vein, Chan’s colleague, uOttawa Faculty of Science professor of biology and environmental toxicology Jules Blais, the director of the Laboratory for the Analysis of Natural and Synthetic Environmental Toxicants, is examining arsenic levels in areas around the Giant Mine site. Last year, he secured a National Sciences and Engineering Research Council of Canada (NSERC) strategic project grant of $570,000 over three years to develop new tools for assessing legacy pollutants and their ecological consequences in lakes near NWT mines.

“There is a halo of arsenic that we can detect in lakes up to 15kms away from the mine,” says Blais. “We are looking exclusively beyond the mine property. Our preliminary analysis is showing that arsenic trioxide levels in the lakes are exceeding levels that are required to protect aquatic life.”

Blais examines core samples of lake sediments to trace the environmental record back through hundreds of years. Clues in the layers, such as the shells of cladocera, which are tiny crustaceans that form a major part of the aquatic food chain, reveal the history of the lake over time, much like the rings of a tree trunk indicate warm years and cold years.

Blais says one aim is to determine whether lake sediments are absorbing the arsenic and taking it out of the waters, or diffusing it. Early results show that arsenic levels in the sediment increased during the decades in which the Giant Mine roaster was melting ore to separate out the gold, particularly before emissions controls were put into place, and that cladocera died off in huge numbers during this period.

“Environmental studies are often like arriving at the scene of an accident. You realize there is a problem after the problem has happened. Our approach allows us to go back and reconstruct what changes took place and look at how the biota responded to past disturbances,” says Blais. “Our research aims to find better ways to learn from our past mistakes.”

Once published, this research will present a well-documented history of the levels of contaminants such as arsenic, mercury, and sulphur dioxide, which will answer questions about what has happened since the mine ceased operations and how the contaminants have moved through the ecosystem. Ultimately, Blais hopes the research will inform future regulators.

“If regulators can better understand the effects of releasing these emissions, like sulphur and arsenic, into the environment, if they are provided with tools to better understand the environmental consequences, then they will be in a better position to regulate these emissions,” says Blais.

Blais and Chan are both inspiring the next generation of well-trained eco-defenders at uOttawa.
 

In 2013, when Chan became aware of the pressing need to educate future generations of environmental toxicologists, he called upon a dozen of his expert colleagues from uOttawa, Carleton University, Université Laval, the University of Alberta, Health Canada and Environment Canada to commit to training more than 100 students over the next six years. To this end, Chan secured a $1.65M NSERC CREATE grant for Research in Environmental, Analytical Chemistry and Toxicology (REACT) in 2014.

Around half of these students are due to attend uOttawa. The first cohort of 15 students started the NSERC CREATE-funded REACT program last September, says Chan, who is director of uOttawa’s Center for Advanced Research in Environmental Genomics (CAREG). Students will be taught how to use the latest technologies and how science contributes to regulating dangerous chemicals in the environment.

“I want to retire one day! We want the next generation of well-trained people,” says Chan. “These students will have a strong background in analytical chemistry and toxicology to track the sources, pathways, fate and effects of different chemicals. uOttawa is in a strong position because we have the involvement and support of a network of government scientists.”

Chan is well-known for his expertise in monitoring how environmental pollutants make their way through the food chain and the potential impact on health. He was lead investigator for the First Nations Food, Nutrition and Environment Study (FNFNES), the first national study of its kind, conducted in partnership with the Assembly of First Nations and the University of Montreal. This study found high levels of food insecurity among First Nations communities: declining access to traditional food from hunting, fishing and harvesting, combined with poor nutritional value in store-bought food, had resulted in poor quality diets. The study identified some chemical contamination of traditional foods and water in certain areas, but found that environmental pollution was generally not a health concern. However, the study called for ongoing monitoring, with FNFNES data to serve as a benchmark for studying future trends.

In 2014, uOttawa expertise was further recognized with two other NSERC strategic project grants awarded.

Vance Trudeau, professor of biology at the Faculty of Science, secured more than $600,000 over three years to study the negative effects of oil sands chemicals on amphipods and amphibians. His research team is examining poorly classified, yet potentially toxic, contaminants associated with bitumen extraction. It aims to provide guidelines on toxicity levels in order to reduce the environmental risks of oil sands exploitation.

The Department of Earth Sciences was also awarded NSERC funding. Professor Jack Cornett, who is also on the CREATE team, secured more than $750,000 over three years to develop, test and demonstrate new methods of measuring potentially harmful radionuclides in water around nuclear power plants. Cornett will use the Accelerator Mass Spectrometer (AMS) at the Advanced Research Complex to develop more accurate spectrometric techniques for measuring radionuclides.

Clearly, uOttawa is at the forefront of efforts to harness the latest scientific research to better protect the world we live in.
 

Main photo:
An aerial shot of the Giant Mine, outside Yellowknife, NWT. Photo: Joshua Thienpont.