Abandoned and flooded mining sites could harbor microorganisms that can decontaminate these hostile environments. To find them, Quebec scientists are working with divers who specialize in exploring underwater caves.
Due to its long history of exploration and exploitation of natural resources, Canada now has many abandoned mines. Thousands of abandoned sites where mineral mining may have contaminated the environment.
In Quebec alone, in March 2022, the Ministry of Natural Resources estimated labor costs related to the environmental liabilities of these former mining sites at more than $700 million.
The search for solutions to rehabilitate these areas is therefore of great interest. The idea drives biology doctoral student at the University of Quebec in Montreal (UQAM) Élise Lhoste and her colleagues from UQAM and the University of Ottawa. They are interested in the microorganisms that live in these hostile environments in the hope of finding species that can contribute to their rehabilitation.
Élise Lhoste is a doctoral student in biology at the University of Quebec in Montreal. Photo: Radio-Canada
Old mines are artificial environments because they were used by humans, which we don’t know at all. So we want to know what organisms are in these environments and why they are there and how they survive. To do this, we need to identify them and understand what function they have in this ecosystem, explains the researcher.
These inhospitable environments could promote the growth of organisms that are particularly adapted to the presence of certain pollutants.
“The goal would be to discover a small bacterium that can break down metals or certain hydrocarbons, and perhaps cultivate it for later use.” »
— A quote from Élise Lhoste, a doctoral student in biology at the University of Quebec in Montreal
Exploring these little-known ecosystems is no easy task. In many disused mines, the craters, shafts and tunnels have been filled with water since they were closed.
They used to remove the water during extractions. Then, later, nature took over and the water rose to the surface as the mine was abandoned, describes Élise Lhoste, perched on an embankment overlooking one of these old mines.
What looks like a small lake is actually a flooded mine. Photo: Radio-Canada / Gaëlle Lussiaà-Berdou
Located in Outaouais, the town looks like a small lake surrounded by steep cliffs.
But the path that leads down to the shore is littered with small, shimmering shards. These are sheets of mica, a mineral that was mined locally from the late 19th century until the 1940s.
At the peak of activity there were around 120 miners working here. At this time there were also mica factories in Hull and Ottawa where women with knives worked on what we call in English “splitting” the mica. A lot of people were busy, it was important, says Alain Delisle, who is involved in the researchers’ work.
These mica sheets are remnants of the exploitation that took place here 100 years ago. Photo: Radio-Canada / Gaëlle Lussiaà-Berdou
Mr. Delisle is not a scientist, but an amateur diver. As a former soldier, he devotes his free time to diving.
With other enthusiasts like him, he has specialized in exploring underwater caves, for example in Florida or Mexico, but also in abandoned mines.
There are many tunnels. “We really enjoy discovering and exploring new passages,” enthuses Mr. Delisle, although he recognizes that it’s not for everyone.
Alain Delisle, a former soldier, dives in underwater caves and abandoned mines. Photo: Radio-Canada / Gaëlle Lussiaà-Berdou
In fact, this type of diving is complex and risky.
At the bottom of the mine, more than 50 meters deep, it is pitch black and even with lamps, visibility for divers is often very limited. They must follow the ropes they have set up during their explorations to avoid getting lost. The temperature is also not very pleasant: it is around 6°C even in summer.
“There are always risks when you go into the mines: rubble, you can get lost in the mine, there is also a lot of sediment. You need really good techniques to swim without having to lift them up. You need to look at yourself and decide if the risk is acceptable to you. »
— A quote from Alain Delisle, amateur diver
Five divers are present this June morning and are accompanied by a discovery team.
Around a map of the mine, which they update as they explore – no historical documents can be found – the team is accompanied by three researchers from UQAM, including Élise Lhoste, who provide them with equipment for their work.
Once their plan is decided, the divers set off to explore the flooded mine. Photo: Radio-Canada / Gaëlle Lussiaà-Berdou
They have sterile bottles and syringes with which they either collect biofilms (clumps of cells, editor’s note) directly on the rock or simply water, which they then bring to the surface, explains the researcher.
Samples collected at different depths of the mine are used to analyze which microorganisms are present and in which environments they develop.
We expect that closer to the surface we will find microorganisms that are different from those in the tunnels, because on the surface we have stores of light, oxygen and nutrients that will be more important than in tunnels, notes Ms. Lhoste .
Beginning of the mosaic of 4 elements. Skip the mosaic?
As soon as the divers surface again, the scientists begin filter work. Some of the water is analyzed to assess its oxygen and nutrient content or the presence of hydrocarbons or heavy metals.
The remainder is quickly brought back to the laboratory to extract the microorganisms before they are broken down.
There, under the hood, Élise Lhoste filters the water and freezes the small white paper filters that contain the bacteria and other microscopic organisms that interest her. She will then patiently extract DNA from these underwater communities in hopes of finding a way to break down certain pollutants.
The microorganisms are captured in small filters. Photo: Radio-Canada
Using bioinformatics treatments, we are able to reconstruct the metabolic pathways present in a community. We can see which genes are present, whether they are expressed and whether there are even genes involved in detoxification phenomena, such things are stated by the researcher.
“If we see that there are microorganisms that can use and break down metals found in the mine, for example, this can later be used to decontaminate certain environments.” »
— A quote from Élise Lhoste, a doctoral student in biology at the University of Quebec in Montreal
Élise Lhoste hopes that her work can help clean up certain environments. Photo: Radio-Canada
In similar work conducted in 2019 at an abandoned iron mine in Gatineau Park, researchers and their diving partners had already found abundant life at depths of up to more than 180 meters.
Time will tell whether there is a treasure in these mining pits that can contribute to their rehabilitation.
The report by Gaëlle Lussiaà-Berdou and Hélène Morin is presented in the program Discovery Sunday at 6 p.m H 30 HERE TV and 22 h HERE Explora and next Saturday at 7 p.m H 30 HERE RDI.