Cleaning up the dangerous contaminants – dry-cleaning fluids, solvents and petroleum hydrocarbons – found in underground water presents one of the most urgent challenges facing environmental science. A recent report issued by the U.S. Environmental Protection Agency (EPA) sheds light on a new way to monitor and improve the success of clean-up efforts using a technique developed at the University of Toronto.
"The most common method
to clean-up ground water is biodegradation – using microbes to consume the
contaminants and break them down into more benign end products that are not
harmful to the environment," says U of T geochemist Barbara Sherwood
Lollar, the scientist who initiated the concept and goals for the EPA report,
and is one of its five international authors.
The report outlines how this
can be done using a novel technique called Compound Specific Isotope Analysis,
developed in U of T's Stable Isotope Laboratory. The elements of carbon that
form the basis for the hydrocarbon contaminants actually come in two types
called isotopes, explains Sherwood Lollar. "When microbes degrade
contaminants, they prefer the lighter isotope carbon 12 over the heavier
isotope carbon 13. The resulting change in the ratio of these isotopes in the
contaminant itself is a dramatic and definitive indicator that the
biodegradation is successfully taking place."
Beginning in the 1990s, U of
T's Stable Isotope Laboratory has been an international pioneer in discovering
how different carbon isotopes can be used to identify whether or not
biodegradation is taking place. "Today, dozens of students in Canada have
been trained in this method, drawn in by the fascinating combination of
fundamental research that has important applications such as the clean-up of
drinking water," says Sherwood Lollar. Over the past decade, as the new
technique has become more widespread, centers for research and education – and
even private companies – have blossomed worldwide.
"Much of the research on
new methods of analyzing ground water contamination has been published in
scientific and professional journals, but this report – written specifically
for the practitioners in accessible language with clear procedural information
and decision-making strategies – is a milestone," says Sherwood Lollar.
"It is particularly
gratifying to be able to take a technique out of the lab and to put it into the
hands of the people working on this issue every day around the world," she
Technique to Test the Clean Up of Contaminated Ground Water
February 6, 2009