Beyond being a haven for wildlife and plant life, wetland areas provide the right mix of chemical compounds and physical characteristics to break down harmful pollutants, according to Ohio Sea Grant research from Dr. Yo Chin, Professor of Geology at Ohio State University.
Chin and his graduate student Ale Hakala have determined that over time, pentachloronitrobenzene (PCNB), an antifungal chemical now banned for use on most crops in the U.S., can be reduced to pentachloroaniline (PCA), a compound that should be more readily broken down by wetland bacteria.
Chin studied the process at Old Woman Creek National Estuarine Research Reserve in Huron, Ohio, using a technique he has perfected over more than a decade that slowly pulls water out of sediment in an oxygen-free environment. Keeping oxygen out is important because the main catalyst in the PCNB-to-PCA reaction is a form of iron scientists call iron 2 (or, Fe(II)). If even the smallest amount of oxygen gets in, the iron oxidizes to Fe(III), commonly known as rust, thereby ruining the experiment.
In the laboratory setting, when the water from the sediment had been chemically stabilized, the reaction turning PCNB to PCA was completed in two hours. But, surprisingly, the same reaction took one week when the team used water that hadn’t been stabilized-the way it would be found in the wetland. This discovery opened Chin’s eyes.
"Everything we’ve done, everything anyone has done with these pore waters, was based on manipulated compounds," he says. "In nature, the compounds aren’t manipulated in that way, so the reaction takes a week instead of two hours. Doing it in the lab allows you to control things, but the take-home message here is that nature doesn’t want to be controlled."
To read more about this Ohio Sea Grant-funded research, visit http://ohioseagrant.osu.edu/_documents/twineline/v31i4.pdf