Clarkson University Magazine: Great Lakes Fish Monitoring

 

PROFESSOR OF CIVIL & ENVIRONMENTAL ENGINEERING THOMAS M. HOLSEN IS LEADING AN INTERDISCIPLINARY TEAM OF RESEARCHERS FROM THREE UNIVERSITIES WHO HAVE SPENT THE LAST SEVEN YEARS QUANTIFYING THE LEVELS OF CONTAMINANTS IN TOP PREDATOR FISH AS PART OF THE GREAT LAKES FISHING MONITORING AND SURVELLIANCE PROGRAM (GLFMSP).

The program began in the 1970s and was taken over with a renewed focus in 2005 by Holsen and his team with a $1.75 million, five-year grant from the Environmental Protection Agency (EPA). In 2010, the researchers received an additional $6.5 million, five-year grant from the EPA to expand their research on contaminants in the Great Lakes ecosystem.

Historically, the project has targeted chemicals like PCBs and DDT that have already been banned and are widely recognized for causing serious environmental and health-related problems. Since these chemicals are already present in the environment, and are no longer used, there is little that can be done to influence their current or future concentrations. 

Now, thanks to improved modeling techniques that help screen chemicals and high-tech analytical instrumentation, the researchers are focusing their attention on a subset of the approximately 30,000 chemical substances in wide commercial use that are not being monitored in environmental media. “Most of these chemicals don’t have characteristics that would indicate they would persist in the environment if released,” says Holsen. “However, others have properties that suggest they may accumulate in the environment and potentially be toxic.

great_lakes_smAmong the new and emerging contaminants are perfluorochemicals (PFCs), which are found in Teflon and stain-resistant products, flame retardants that are added to many commercial products and synthetic fragrances that are used in products ranging from cosmetics to detergents.
Finding these contaminants requires several new approaches. The team has acquired more than $1.3 million in state-of-the-art analytical equipment that will allow them to analyze for new classes of contaminants at levels that were not previously possible. In addition, the researchers are now analyzing other media for contaminants including water, plankton and zooplankton, trout eggs, fish low on the food chain and organisms that live in the sediments.

“In the past, the project has targeted only top predator fish as bioindicators, notably lake trout and walleye, because they have been regarded as sentinels of the overall condition of the Great Lakes system,” says Holsen. “However, these new chemicals will likely behave differently than previously targeted compounds and may show up at detectable levels in other locations first. This broader approach allows us to identify problem chemicals before they become serious environmental problems.”

Through these studies, the team hopes to improve the understanding of contaminant cycling and bioaccumulation of toxic chemicals in the Great Lakes and also provide policymakers with the information they need to limit the release of potentially harmful chemicals into the environment and safeguard human health.

 

 


 

 

Quantifying Toxaphene Levels in Great Lakes Fish



taxopheneToxaphene is a chlorinated insecticide that was widely used starting in the 1940s. In the United States it was primarily used on cotton crops in the southeast.  After it was discovered to be carcinogenic and persistent in the environment, it was banned for most uses in the U.S. in 1982. It belongs to the so-called “dirty dozen,” a list of highly toxic substances, eleven of which were outlawed in May 2004 when the Stockholm Convention went into effect.

Once applied to crops, toxaphene can
volatilize into the air where it can be transported to regions where it was not originally applied. In the Great Lakes region, toxaphene has been found to be ubiquitous and has been measured in the air, rain, water, sediment, and fish.

Holsen and his research team are quantifying the levels of toxaphene in top predator fish. Their results have shown that total toxaphene concentrations are statistically highest in Lake Superior lake trout (119-482 ng/g), and lowest in Lake Erie walleye (18-47 ng/g). As the largest, deepest and coldest Great Lake, Lake Superior’s large surface area and colder temperatures enhance gas absorption and partitioning to phytoplankton increasing the concentrations available to the overlying food web. Concentrations in all of the lakes have generally declined between 2004 and 2009 with total toxaphene concentrations appearing to reach a minima in 2007.  Overall toxaphene concentrations are decreasing with a half-life (t1/2) of six to ten years.