A method developed by researchers at the University of Windsor promises to speed turning toxic tailings ponds left by petroleum mining into sustainable wetlands.
A team led by biology professors Chris Weisener and Jan Ciborowski of the Great Lakes Institute for Environmental Research spent the summer in Alberta successfully testing their method.
The patented process involves exposing to gamma radiation the sediment of tailings ponds—storage basins of the leftover toxic mix of residual oil, water, sand and clay that comprise the byproducts of oil refining. Irradiating the sediment breaks down the toxic compounds and creates a food source for microorganisms.
“The irradiation process is creating a bio-available carbon source for bacteria called degraders, and this gives the bacteria a boost,” says Dr. Weisener. “In other words, it creates an abundance of readily available food, like taking lobster meat out of a shell and presenting that meat, instead of having to go to all the fuss of shelling it.”
Weisener says irradiation reduces toxicity right off the bat, and though the researchers are still playing with how quickly it works, they have found it speeds up the remediation process by at least 50 percent.
Danielle VanMensel, a master’s student in Weisener’s lab, has been investigating the effects of irradiation on the sediment’s microbiological community.
“The irradiation effectively sterilizes the material, then we reintroduce the original microbial community, which starts breaking down the toxins,” she says. “I study how the community shifts and changes in both the samples we left alone, as well as the irradiated samples, and we have found that these microbes may play a huge role in bringing the sediment back to a remediated state.”
Doctoral candidate Thomas Reid and master’s student Chantal Dings-Avery are looking into the irradiated material under natural conditions like rainwater, sunlight, bugs and plants.
“This is a new and faster approach that is a big plus because it costs industry millions of dollars to reclaim these sites,” says Reid. “This is a safe method that uses irradiation exposure, the kind used in the food or medical industry.”
The team got a unique opportunity to fly with Environment Canada into undisturbed sites near Fort McMurray. Reid says these reference sites have not been touched by human production and can give an understanding of the kind of sustainable wetlands they are striving to recreate.
He says they are studying how the microbes behave at the most basic level, to see how or if that activity differs between bacteria living in the undisturbed sites compared to those in the mined oil sands sites: “Understanding what microbes are actually doing in these undisturbed sites is something that’s never been done before, it is a great reference point.”
The team is also testing that irradiation is not creating any additional toxic byproducts. The research to date has not uncovered any negative ramifications.
Weisener’s research partner Dr. Ciborowski is studying how the irradiated material effects plants and bugs.
“This method could potentially affect the whole ecosystem because bacteria are the front line,” says Weisener. “Bacteria are the primary producers, so they will influence the chemical environment, which allows other forms of life to establish, and this was our goal.”