Twenty-four hours a day, 365 days of the year, lakes are slowly accumulating mud or sediments. And in that mud is a remarkably clear record of what happened in the lake, of fossils of organisms that lived in the lake are there. And this is one of the main things I do here at my lab at Queen’s University. This is often blended by the work that Jules Blais does at the University of Ottawa, where he does the chemical side of things.

We can use radiometric methods like radio carbon dating or lead 210 to determine the age of all of these different sediment intervals. And this gives us like a history book of environmental change. But the other advantage that lake sediments give us is that lakes are common on the landscape, and so we can take sediment cores from lakes that span a geographic range. So this has enabled us, for example, to look at the distribution of PCBs globally and track their movement from southern latitudes towards northern latitudes in a sort of distillation of certain chemicals that tend to be attracted to colder temperatures.

Working with Environment Canada colleagues, we’ve worked in the oil sands region to try and reconstruct going back in time. Have the oil sands actually affected lake ecosystems, and are they actually contributing to the pollution of local lake ecosystems? Some issues are at a more local level. Working, for example, with the Ontario Ministry of the Environment, we can look and use our methods to show, for example, how many cottages can you put around a lake before – before you have problems with algal blooms, for example? And you can help use this information to set those types of policies.

This is a collaboration that began many years ago. John Smol and I are actually maternal half brothers.

When we started our careers — Jules is younger than me — we worked independently. We didn’t really work very much together, but over the years, we saw many similarities in our work and started quite slowly, and over the last 10 years or so, we’ve been working quite closely on a number of projects.

One of the things that we’ve been able to do that we’ve really enjoyed is applying our techniques to new fields of inquiry, and one of those has been to the field of archaeology. There are settlements across Canada’s far North that were settled by the Thule. These were communities that hunted whales, so they were a whaling society. They left behind these archaeological sites, so we have a sense of where they were, but we haven’t had a very strong sense of when they had been there. But because we can take cores from the ponds near where they settled, we can determine the timing of when these settlements occurred.