Maryland, September 20, 2004 (ENS): Researchers
and public officials concerned about pharmaceuticals,
personal care products and pesticides that have been
detected in soil and water now have a new mathematical
tool that accurately predicts how long such pollutants
will remain in soil.
Johns Hopkins researchers have created a way to determine
the extent to which hazardous contaminants will linger
on a piece of land and the rate at which they will migrate
toward water resources.
The new approach will help regulators decide whether
the pollutants need to be removed and how best to accomplish
this, the researchers say.
"If we release chemicals into the environment,
we need to know what will happen to them," said
Thanh Helen Nguyen, a graduate student who played a
leading role in adapting the math tool and demonstrating
"For many years, we've made predictions with a
method that doesn't work very well on many chemical
pollutants in soil. This new tool does a much better
For years, environmental chemists have made predictions
about how long the non-ionic pollutants will stay there
by using octanol, an organic solvent, as a chemical
stand-in for natural organic material. "But this
technique doesn't work very well for polar pollutants
that interact with surrounding solids in a more complex
way," Nguyen said.
The doctoral student gathered 359 data points from
published experiments involving 75 chemical pollutants.
She then borrowed a medicinal chemist's method of converting
each of the 75 pollutants to a mathematical representation.
"We worked with these numbers and came up with
a very simple equation that predicts what fraction of
these non-charged chemicals will make their home in
the soil rather than water under any given set of conditions,"
Nguyen said. "The equation works very well with
complicated chemical structures like pesticides and
Nguyen, who is working toward her doctorate in the
Department of Geography and Environmental Engineering,
described the improved pollution predictor during an
August 26 presentation in Philadelphia at a meeting
of the American Chemical Society. "We've had a
generally positive reaction to this technique so far,"
Nguyen told meeting attendees. The researchers' goal
is to now move the technology into the mainstream where
more environmental regulators and practitioners will
have access to it.
Nguyen grew up in Vietnam and completed her undergraduate
studies at the Ivan Franko National University of L'viv,
Ukraine. Before enrolling at Johns Hopkins, she earned
a master's degree in earth and environmental sciences
at the University of Illinois at Chicago.