Published on Brock University (http://www.brocku.ca)
Rosalie Zielinski-Lawrence, a recent Brock MSc graduate in chemistry, is too young to remember the headlines that made the Hooker Chemical and Plastics Corporation notorious for its toxic waste dumping practices.
As a young Brock scientist, her research interests are focused on studies to help monitor the lasting environmental impact on Lake Ontario from the Hyde Park landfill in New York State where Hooker dumped industrial waste from 1953 to 1975.
This research has the support of the Ontario government’s Best in Science program. Zielinski-Lawrence’s recent graduate work, supervised by Ian Brindle, dean, Faculty of Mathematics and Science, and a leading expert in environmental analytical chemistry, was one of 16 projects that received funding from the program in 2009.
She conducted a study to measure the levels of a fluorinated compound throughout a sediment core from Lake Ontario’s Mississauga basin. The Hyde Park landfill is the only known source of this compound and changes in its concentration, in a dated core, can be used to tell us about migration of chemicals from the landfill. Since this landfill is estimated also to contain between a tonne and a tonne and a half of a potent carcinogen, called 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD or simply dioxin), it is important to know if anything is leaching from the dump.
“We know that the Hyde Park landfill is the only source of this fluorinated compound – studying its distribution in Lake Ontario is significant as a means by which to monitor the site,” says Zielinski-Lawrence.
She emphasizes that more work needs to be done to establish if contaminants could continue to leach from Hyde Park — a landfill that carries the reputation of being the largest known dioxin dump in the world.
For the purpose of her study, Zielinski-Lawrence analyzed a sediment core for the presence of the fluorinated compound. The dated core represents a timescale – the deeper you go, the earlier the date of deposition of the sediment. This analysis allowed her to chart a chronology of contamination levels. The data tells a predictable story of the history of the Hooker dumping activities – sudden appearance in in the early 1950s, rising to a peak accumulation about 1970, followed by dramatic decreases in concentration reflecting the period when the dump was closed and remedial efforts were taken by Hooker.
This information will be useful in determining the rate at which this fluorinated compound’s level is decreasing. A study in 1996 projected that it would take 15 years for the concentration to diminish to five per cent of its maximum. Her results showed levels, corresponding to the time the core was taken in 2004, had reduced to 26 per cent of the peak accumulation. This result suggests that the concentration is not decreasing as expected, and that chemicals are potentially still leaching from the landfill.
“We will need to study many more sample cores from other locations in the lake to draw any definitive conclusion about the status of the landfill,” she says, “and we may be able to take a look at suspended sediments that flow from the Niagara River, to see whether they are picking up this fluorinated compound if it is still being released from Hyde Park.”
Zielinski-Lawrence, now working as a lab technician at Brock, plans to continue her work.
“You just have to think about Lake Ontario to grasp the significance of this research,” she says. “Seven million people drink water from Lake Ontario. It’s used for recreation purposes. It’s home to a variety of aquatic life. It’s important to know what is in the water.”