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Thawing sumps leaking into nearby lakes in Mackenzie Delta Region, research says

By Rosie Hales, Communications Officer

Photo by Joshua Thienpont

Sumps in the Mackenzie Delta region that were constructed in permafrost during the 1970s and 80s aren’t staying permanently frozen, says Queen’s professor John Smol and former Queen’s PhD student Joshua Thienpont.

These large man-made pits containing waste from oil and gas exploration activities were constructed in the permafrost of the Northwest Territories with the intention of remaining frozen. Due to thawing,the waste in these sumps is migrating into nearby lakes, resulting in changes to the chemistry and biology of the water.

“The idea was that these sumps would become part of the permafrost,” says Dr. Thienpont, chief author of the study. “However, the waters in there have a high salinity and therefore have a lower freezing point. Our data shows that the freshwater lakes near the sumps are chemically different and these changes happened close to the time that the sump was constructed.”

There are currently over 200 sumps in the upland terrain of the Mackenzie Delta. The team tested the waters in over 100 lakes in the region and analyzed data that was collected in 2005 and 2007.

The research, which was published in PLOS ONE, took about two years to complete and suggests that the construction and abandonment of these sumps can lead to pollution.

“Lake sediments leave a history of our environmental victories and sins,” says Dr. Smol. “The sumps were supposed to be permanently frozen but their thawing is a yet another warning sign that there are consequences to industrial activities. Permafrost sumps such as these are not the way to get rid of waste.”

The team's research can be found here.