Scientists find pattern of contaminants tied to decades of development in the oilsands

By Sarah O’Donnell, Edmonton Journal January 7, 2013
EDMONTON – Scientists working to trace the environmental legacy of the oilsands industry say there is “clear science-based evidence” connecting the pace of oilsands development to the amount of toxic substances found on lake bottoms north of Fort McMurray.

University of Alberta water scientist David Schindler says that work by a team of Queen’s University scientists and Environment Canada researchers signals an urgent need to rethink how the province develops the industry.

“This study once and for all lays to rest the popular propaganda that all the pollutants up there are from natural sources, because by this fingerprinting technique they’ve used they’ve been able to separate those from natural erosion from those that aren’t,” Schindler said.

“The latter category track almost exactly the rate of expansion in the oilsands industry.”

The research, published Monday in the U.S. journal Proceedings of the National Academy of Sciences, details how sediment samples from the bottom of six lakes, including one nearly 90 kilometres away, show an increase in carcinogenic pollutant levels over the years that mirrors the expansion of the oilsands industry.

Looking at core samples of lake bottom sediment, scientists measured for a range of substances, including polycyclic aromatic hydrocarbons, a diverse group of chemicals produced by the incomplete combustion of fossil fuels or from natural sources such as forest fires.

PAHs are carcinogenic at high levels and rank in the top 10 most hazardous substances on the U.S. Agency for Toxic Substances and Disease Registry. They are a concern to aquatic life in even small doses.

Testing found those substances in the most recent sediment layers at levels 2.5 to 23 times greater than 1960 levels. The study notes that those levels were still within Canadian interim sediment quality guidelines in all but one lake.

Recent lake sediments also contained lower levels of some chemicals compared to many urban lakes and those within 10 kilometres of Alberta’s coal-fired power plants.

But the study says those pollutants, combined with the effects of climate change, have led to “new ecological states completely distinct from those of previous centuries” in those lakes. A commentary on the research by Queen’s University’s Peter Hodson, an expert in the field of fish toxicology, warns of possible problems.

With those increases “and the projected 150-per-cent increase in oilsands production over the next 15 years, there is reason for concern,” Hodson wrote, adding that the study provides “a clear warning of possible future problems if PAH inputs to lakes continue to climb in tandem with oilsands production.”

The paper notes that the core samples from the lakes around the oilsands development did not fit the pattern of many other remote lakes in North America, where PAHs peaked during the mid-20th century and declined in more recent years.

Schindler said the study sends an important message that independent monitoring must be set up quickly.

“It’s an example of the very sort of reasons we need this detailed monitoring,” Schindler said. “There are lots of projects that are in the planning stage and obviously that’s the time to start taking these things into account, so you don’t have to do expensive retrofits later. Hopefully that will be a benefit of this study.”

The research, which looks at five small, shallow lakes and one larger lake about 90 kilometres away, previously made headlines in November.

Environment Canada scientists presented some of the findings at an international environmental toxicology conference. And Derek Muir, a senior scientist with the federal agency, detailed how the footprint of the oilsands pollution had travelled further than expected over the decades.

That built on a study by Schindler and colleague Erin Kelley released in 2010 that showed heavy metals in the snowpack up to 50 kilometres from oilsands production sites.

Joshua Kurek, lead author on the newly released study, said researchers wanted to use the science of paleolimnology to determine what ecosystems in northeastern Alberta were like prior to the development of the oilsands industry.

“The techniques paleolimnology affords can be quite powerful: Looking at the historical records preserved in natural archives of waters, like lakes,” said Kurek, a post-doctoral fellow in Queen’s University’s biology department. “We can look at the physical, chemical and biological remains in the sediments to understand past patterns and processes.”

Environmental monitoring in the region has been criticized as inadequate. So researchers set out to answer two basic questions: Have contaminants in the lake sediments increased over time? Could those contaminants be directly connected with oilsands development, rather than residue from the naturally occurring bitumen deposits?

Looking at core samples is not quite like analyzing tree rings, which can allow experts to see seasonal growth in a single year.

Instead, the 20- to 40-centimetre long core samples measure several hundred years in time. Those samples are chopped up into intervals, which represent a time range. Kurek said the team is confident of the pattern within the margins of error outlined in the paper.

“We show fairly clear evidence the loading of PAHs have increased and that increase is coincident with the development that began in the late 1960s,” Kurek said. “We show the timing of the increase, but we also show the composition of the PAHs in the sediment record is also indicative of a shift to hydrocarbon sources for those PAHs.”

Travis Davies, a spokesman for the Canadian Association of Petroleum Producers, recognized the study as part of the growing body of science around the oilsands industry.

“We’re supportive of good science and measuring the fact that these compounds are present is important, but so is context,” Davies said, pointing to the finding that the lakes in the study have lower levels of the pollutants than typical urban lakes.

The results point directly to the importance of enhanced environmental monitoring, he said, something CAPP supports.

In November, after Environment Canada scientists presented the results of their research at the international conference, Alberta Environment and Sustainable Resource said the province will take advice from its science advisory panel on future guidelines and limits for the oilsands industry.

Minister Diana McQueen said it was important to set up the new arm’s-length environmental monitoring agency correctly. Estimates from government officials are that it will take anywhere from six months to two years for the agency to begin its monitoring work.

“The important part is that we set it up, that we get it set up right and properly,” McQueen said in November. “This is going to be here for the long term, just starting in the oilsands region and then across the province.”

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