The Chronicle Herald (Provincial)
Fixing gold mining's toxic past
Linda Campbell’s research into finding a way to cost-effectively clean up toxic waste left over from old gold mining sites in Nova Scotia is being turned up a notch.
Campbell, a professor in the School of the Environment at Saint Mary’s University in Halifax, has been leading a team looking at developing remediation methods in the lab that can be applied to cleaning up untreated tailings dumped into wetlands and shallow-water areas throughout the province.
The trick is to clean up the toxic waste without creating a greater environmental problem.
Campbell, speaking through a sign-language interpreter, said in an interview that the research shows it can be done, and that should be an indication the plan will be successfully applied on a larger scale.
“It goes back to looking at our wetlands. They are so important to us, they are economically valuable to the province, we need them for recreational purposes, for carbon sequestering, for water purification, fish habitat and really a whole myriad of different services are provided by wetlands, which is why they are so important and it is important we don’t lose the wetlands in our province,” said Campbell.
“And our goal is to protect (against) the loss of wetlands .
. . and part of that challenge is how do you clean up these wetlands that have been contaminated
for over a hundred years? And the contaminants are still impacting the wetlands today, so that is a huge challenge for us.”
MINING FIRM
The Saint Mary’s team recently received support for its work from gold mining company St. Barbara Ltd. The Australian company owns Atlantic Gold, operator of the Moose River gold mine near Middle Musquodoboit, and has plans for three more mines along the Eastern Shore.
Atlantic Gold has agreed to help finance Campbell’s research over five years. The first
payment of $200,000 was made in late 2020.
Campbell said she has been giving presentations about her research to anybody who has been interested or who reached out, in order to tell them about what is being done to solve the historical tailings problem. Several Nova Scotia entities became aware of her work and contacted her.
Remediation is an expensive undertaking, with a 2019 estimate pegging the cost at $48 million to clean up the Crown land portion of just two of Nova Scotia’s legacy tailing sites.
Traditionally, toxic tailings
have been capped or waterways have been diverted, or there are other engineering methods of dealing with the problem that lead to a loss of wetlands and really don’t accomplish the goal of neutralizing the environmental threat, Campbell said.
She is joined in the effort by senior project research manager Emily Chapman, and she expects to hire several students to help implement the remediation plan developed in the lab.
The method uses a thin layer of reactive material to neutralize toxic elements in the tailings. It has proven to be successful in a proof-of-concept study at limiting the risk of disturbing the toxic material, Campbell said. If disturbed, the toxic tailings would have the potential of being destructive to environmentally sensitive areas.
OLD MINES
The days of mining companies simply tossing away tailings and forgetting about them ended some time ago. But there are plenty of abandoned mines throughout the province that have contaminated wetlands and shallow water sources for years.
There are about 300 abandoned mines in remote areas and backyards, according to the university. Contamination from the arsenic and mercury used in past gold mining practices can affect human health and risk environmental contamination.
Research by the university from 2015 to 2019 shows that sediment samples from legacy gold mine tailings in wetlands remain contaminated and are still toxic to aquatic invertebrates many years after they have been discarded.
The aquatic invertebrates are an important part of the project, Campbell said, because they are sensitive to toxic minerals and would provide a warning they were being released, similar to a canary in a coal mine.
“Our goal is to ensure legacy arsenic and mercury contaminants will not continue to be a problem for Nova Scotians for another hundred years,” she said in a Saint Mary’s news release.
If proven effective, the method proposed by Campbell and her team will have an immediate benefit to Nova Scotia and potentially for former gold mining sites around the world.