"Over the last couple of generations, there has been a huge amount of ground water pollution worldwide, and this has had a negative impact on our drinking water supply," says Barbara Sherwood Lollar, Canada Research Chair in Isotope Geochemistry of the Earth and the Environment at the University of Toronto. Her research examines society's efforts to reverse and stop ground water pollution, and the effectiveness of bioremediation technologies – using microbes to clean up organic contaminants such as petroleum hydrocarbons (oil, gasoline or diesel) or chemicals used in the electronics or transportation industries.
disposal of these organic contaminants tends to be well regulated today, this
has not always been the case. Lax regulations and enforcement during the period
immediately after World War II has left Europe and North
America with a legacy of past contamination.
contamination has had a pervasive impact on the environment," says
Sherwood Lollar. "It is still out there, and it needs to be dealt
past decade, many techniques used to clean up ground water contamination have
harnessed the power of microbiology and the work of geochemists like Sherwood
Lollar. "We are not genetically engineering microbes," she explains.
"In many settings, naturally occurring microbes feed off the organic
contaminants and, in the process, convert them to non-toxic end products."
the real difficulty has been in proving that the process exists and that the
microbes actually are cleaning up the contaminants. Sherwood Lollar has
developed techniques that show where the clean-up is happening and, just as
importantly, where it is not.
like carbon have different stable isotopes: Carbon-12 and Carbon-13. One is
slightly heavier than the other, and the microbes tend to feed mostly on the
lighter one. When the microbes have been working for some time, the ratio of
heavy-to-light carbon will change. It is this change – referred to as an
isotopic signature – that lets us know the water is being cleaned up,"
says Sherwood Lollar.
up contaminated ground water, it is possible to recuperate what otherwise would
be a lost resource. The technique is starting to be used by regulators, and
Sherwood Lollar is working with an international group of scientists to put
together a guidance document for the United States Environmental Protection
provide a set of recommendations about use in the field for practitioners,
which will be a first step towards mainstreaming the technique.
a common misconception that water – and especially our supply of ground water –
is a renewable resource," says Sherwood Lollar. "But it isn't. So, it
is particularly important that we manage it well and that we do whatever we can
to conserve, protect and remediate what we have."
Evaluating Ground Water Pollution and Clean-up
February 21, 2011