By the time she finished her postdoc in the mids, she thought environmental monitoring of halogenated compounds was on its way out. But a few years later, Li began hearing about polybrominated diphenyl ether PBDE flame retardants accumulating in the environment.
TEACH: Water Contamination in the Great Lakes – Teach Great Lakes
The chemicals are used in plastics, textiles, and other materials to prevent fires during an electrical short circuit or automobile accident and to block the spread of house fires. Penta- and octaBDE were phased out in the U. They have been replaced by a new generation of flame retardants, such as bis tribromophenoxy ethane BTBPE , which on average have a lower density of bromine atoms.
Her team has now collected more than 1, sediment samples from across the Great Lakes. That is also true in more recent years for penta- and octaBDE at most sites. Sediment sampling has an advantage over air, water, and fish sampling in that the cores provide an instant chronology of pollution, Li says. That history has revealed that in some cases older compounds such as PCBs are now exiting sediments rather than building up in them.
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Microorganisms have evolved to feed on and break down natural and synthetic organohalogens that end up in the sediments, she notes. But the data show that process is quite slow in sediment. Li hopes that genomic analysis will reveal the microbial communities that are breaking down the halogenated compounds.
Status of Tier 1 and Tier 2 chemicals in the Great Lakes basin under the Canada-Ontario Agreement
The idea is that scientists might be able to engineer microbes to use in remediation efforts to clean up persistent pollutants. The Great Lakes region is just one place where researchers are studying trends in chemical pollutants. Environmental organic chemist Robert C.
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Hale of the Virginia Institute of Marine Science VIMS , a state research, education, and advisory organization, has spent the past 30 years wading around in streams and poking around in the sludge accumulating in wastewater treatment plants. The cyclic organochlorine compound was being manufactured at an Allied Chemical facility near Richmond. The company improperly handled the material and dumped waste into the James River. The ban remained in effect for 13 years. Hale became part of the VIMS team that studied river sediment and fish to track the progress of Kepone clearing from the ecosystem.
That led him to begin investigating sewage sludge as a repository of synthetic chemicals, studying how he could use contaminants in sewage sludge to track commercial and agricultural chemical production and use. The strategy has helped Hale pinpoint other surprising sources of persistent organic pollutants. For example, he was part of a team working on the Hyco River in Virginia in that found the flame retardant pentaBDE present at nearly 50 ppm in fish, the highest level ever recorded at the time.
The company has since gone out of business. To that end, last year Rolf U. The researchers currently are collecting municipal sewage sludge from wastewater treatment plants to catalog data on contaminants. Knowing that PCBs, flame retardants, pesticides, and antibiotics are lurking in sewage sludge creates a concern over the growing use of the material as fertilizer and compost in agriculture, landscaping, and home gardening, Hale says. Sewage sludge is rich in organic matter and traps a lot of nitrogen and phosphorus, making it a good fertilizer, Hale notes.
The situation reminds Hale of an environmental problem in his native Michigan that helped spark his desire to be an environmental chemist. In , when Hale was still in high school, a Michigan animal-feed distributor accidentally added polybrominated biphenyl flame retardants to feed. The tainted feed gradually poisoned many animals across Michigan and contaminated milk, eggs, and meat in the state. If we contaminate soil with sludge containing PBDEs, we might have a renewed problem.
Sludge might best be packed away in landfills engineered to keep pollutants out of the environment. But landfills are expensive.
Wastewater treatment plants can offset operating costs by giving away or selling the sludge, which is an inexpensive option for farmers. EPA has established regulations on the use of sludge, but the emphasis is on heavy metals and pathogenic microorganisms. Someone asked Hale recently what it would take to do a complete analysis of sewage sludge.
Given how small the list of known problematic chemicals in the environment is versus how many chemicals are in commerce, he says the cost of the task would rival that of looking for a cure for cancer. But the question has gotten Hale to thinking. He envisions that a more thorough analysis of new and archived sludge samples could be synced with human health data stemming from blood and DNA testing to help map out how people react to a lifetime of chemical exposures.
If there is a link and they can understand the mechanism, the researchers could have a shot at figuring out a new way to treat cancer and other diseases or possibly accurately predict and prevent diseases, he suggests. Hale thinks similar connections could be made from parallel studies of sewage sludge.
It would be immense. Environmental measurements on persistent pollutants have gone a long way in helping clean up and protect the environment. But he thinks society has become wiser in the process. Instead, he says, the focus is on finding better substitutes.
Hites could have passed off his project to someone else long ago and retired to focus on his woodworking hobby. But he keeps making measurements because of his professional interest and natural curiosity.
Contact us to opt out anytime. Volume 93 Issue 9 pp. Cover Story. The continued expulsion of these toxins pose serious environmental and health problems for all countries, including those who have long since banned these chemicals, according to the U. Environmental Protection Agency. Climate change may further complicate the issue. As countries like China develop, they are not only becoming the largest emitters of carbon dioxide but of persistent organic pollutants or POPs, according to the International POPs Elimination Network.
These chemicals drift into the atmosphere or fall to the surface to evaporate. And they accumulate in animals and humans. Many have been linked to cancer, diabetes and other illnesses. Persistent chemical compounds travel long distances and eventually concentrate in colder environments to condense and fall back down, said Staci Simonich, a chemistry professor at Oregon State University.
The Great Lakes are a magnet for such pollutants. During the U. Though now banned for decades, POPs from American soil continue to harm the lakes.