PCB breakdown in rivers depends on sediment-specific bacteria, find Carnegie Mellon U. ...( timately hopes to coax bacteria with a ...)

timately hopes to coax bacteria with a preference for PCBs into becoming more dominant life-forms in sediments. Future studies that modify nutrients in sediments from contaminated sites with little or no bacterial activity also could reveal ways to transform sites with poor eaters into areas that grow microbes with healthy appetites for PCBs.

Ideally, the investigators could identify a combination of nutrients or other factors that could be added to river sediments to accelerate the breakdown of PCBs in situ, without having to dredge a river. Should dredging be needed, their research also could identify ways to break down PCBs in sediments that are disposed in secure, hazardous waste landfills. Ultimately, the team's work could result in approaches that detoxify PCBs much more thoroughly and much faster than any existing method.

While other studies have shown that unique populations of PCB-digesting microbes inhabit different waterways, the investigators believe that this is the first side-by-side comparison of populations using the same experimental approaches under identical conditions.

Despite 30 years of scientific investigation and search for remediation approaches, the contamination of waterways with PCBs remains a pressing environmental challenge. A mixture of 209 related chemicals, PCBs accumulate in fish and birds high in the food chain, crippling their ability to reproduce. These agents also build up in humans, where they are suspected of harming reproduction, causing cancer, injuring the immune system and thyroid gland, and impairing learning and memory.

PCBs were generated worldwide largely by industries that manufactured plastics, paints, lubricants, transformers and other materials. In the mid-20th century, companies along the Hudson and other rivers in upstate New York collectively released more than one million pounds of PCBs into the water, not knowing that these pollutants could linger for thousands of years. While U.S. p
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Contact: Lauren Ward
wardle@andrew.cmu.edu
412-268-7761
Carnegie Mellon University
22-Aug-2004

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