Danbury To Use Trees To Reduce Hat Industry-Era Mercury

DANBURY (AP) — Scientists are using trees in an attempt to decontaminate soil polluted decades ago with mercury from the city’s long-gone hat-making industry.

The city planned to begin a research project this month, planting bioengineered cottonwood trees in a vacant lot to draw mercury from polluted soil.

About 60 cottonwood trees, genetically altered at the University of Georgia to better absorb mercury, will be planted next to 60 cottonwoods without any modification.

Two biology professors at Western Connecticut State University will work with students to study the microbiology of the soil, examining the combination of soil chemicals and microbes that help the plants absorb the mercury.

Scientists hope to save the city the $500,000 it would cost to remove and replace the contaminated soil.

“It’s a pathway and a blueprint for other sites in the state,” Mayor Mark Boughton said Tuesday.

Jack Kozuchowski, Danbury’s director of environmental and occupational health services, is continuing studies he began in 1978 when he showed how phragmites, a common reed, reduced mercury levels in polluted soil at Onondaga Lake near Syracuse, N.Y.

The state Department of Environmental Protection allows 610 parts per million of mercury on industrial sites and 20 parts per million on residential sites.

At the site of the old Mallory Hat factory, the city has found readings of about 62 parts per million. The mercury level from one soil sample in the vacant lot is 300 parts per million.

Mr Kozuchowski said the city will also monitor the transpiration of mercury from the cottonwoods into the atmosphere.

It’s unlikely mercury from the plants will exceed pollution levels, but if the “unexpected happens and we get large releases of mercury, we’ll just cut the trees down,” Mr Kozuchowski said.