June 9, 2003
Student's path to graduate school began with
undergraduate research project on drinking water contamination
By Shawna Williams
Two years ago, when testers detected a notorious form of
the metal chromium
in Santa Cruz County's Aromas Red Sands aquifer, residents
water comes from the aquifer faced urgent questions. Would the chromium
make them sick? And where was it coming from?
After graduating from UCSC, Ana Gonzalez has stayed on to
earn a master's degree in environmental toxicology.
The 2000 film Erin Brockovich, starring Julia
Roberts, was based
on a case involving drinking water contamination from
of chromium; the resulting legal battle ended in a $333 million award
for the plaintiffs. One form of the metal, chromium-6, has been shown
to cause cancer when inhaled. No studies have found that chromium-6
causes any ill effects when ingested, however, so both the movie and
the legal case provoked controversy.
The movie probably contributed to the publicity and the
the findings in Santa Cruz County. Ana Gonzalez, then a
senior at UCSC,
and her thesis adviser, environmental toxicology professor
decided to take a closer look at the situation. Their first question
was a basic one: Were the test results real? Or had the
introduced contamination of their own?
Answering this was a tough thesis project for an
undergraduate to tackle,
but Gonzalez did so with gusto. Now a first-year graduate student in
Flegal's lab, she continues to investigate the sources of
in drinking water.
Flegal runs one of the world's leading labs for detecting
in water. Much of the lab's work focuses on toxic trace metals such
as lead and mercury and their effects on aquatic life in local bodies
of water, such as San Francisco Bay.
When measuring concentrations of trace elements in the
parts per billion
range, avoiding contamination is key. Flegal's lab employs a variety
of techniques to ensure the accuracy of results. For example, much of
the testing equipment is coated with teflon to prevent
metals from leeching
into a sample, and all equipment is washed in acid before
use to remove
Flegal's lab had not studied chromium levels in groundwater before,
so Gonzalez had to find out which techniques would work for measuring
chromium, and set up all of the sampling equipment.
"She had to set up the sampling system and the
are things that can take years to do, and she did it in a matter of
months," Flegal said.
Gonzalez received valuable guidance from postdoctoral fellow Kuria
Ndung'u, who had designed a new separation method for
chromium for his
doctoral dissertation at Lund University, Sweden. An
of the analysis was separating chromium-3, a positively charged form
of chromium, from chromium-6, its negatively charged
"Chromium-3 is a trace nutrient, and it's thought
that your body
needs a little bit of it, but chromium-6 is carcinogenic
when it's inhaled,
so it's sometimes referred to as the bad chromium,"
Gonzalez sampled 23 sites for the project, used a filtering system
to separate the chromium-6 from the chromium-3, and
measured the levels
of each. Her findings confirmed that most of the chromium
in the groundwater
she sampled is chromium-6, but that the levels are well
current maximum contaminant level for the metal. She also found clues
to the source of the chromium-6.
"If it was a man-made contaminant, you'd expect to find an even
spread of chromium, with the highest level near where the
seeping into the water," Gonzalez said. "But what we found
is that it's sporadic throughout the sampling area, and so we think
it's from a natural source."
A later assessment done by consultants hired by the water district
confirmed that the chromium-6 in the Aromas Red Sands
aquifer is naturally
occurring. Chromium-3 occurs naturally in some rocks, and
as the rocks
weather the metal ends up in the soil. Under certain
chromium-3 in the soil can turn into chromium-6 and
dissolve in water.
Gonzalez's thesis project won the Dean's and Chancellor's Awards for
undergraduate research in 2002. She also presented her research at a
poster symposium at UC Riverside sponsored by the California Alliance
for Minority Participation, and won the award for best
poster in physical
and engineering sciences.
But Gonzalez didn't stop there. She chose to stay at UCSC to earn a
master's degree in environmental toxicology, and is now testing local
soil samples to see under what circumstances they might
into the groundwater.
Ultimately, Gonzalez hopes to use what she learns to
describe how chromium
behaves in an aquifer. Using equations to describe the
that favor one form of chromium over another, she hopes to build an
analytical model of the Aromas Red Sands aquifer that can be used to
predict where chromium-6 is likely to occur in the aquifer. The same
approach could be applied to other aquifers with naturally occurring
"Ana's project will help us come up with ways to make our water
safer," Flegal said. "Chromium is a problem in California
because a lot of the rocks here have high levels of
chromium in them--natural
chromium. So it's important to determine not only if you're getting
contamination, but also whether it's from a natural source."
Gonzalez will study not only the factors that lead to the presence
of chromium-6 in water, but also under what conditions it
might be changed
back to chromium-3. This will be especially relevant if lawmakers set
a new, lower limit for chromium-6 in water, an idea now
Gonzalez thinks one option for lowering chromium-6 levels might be to
draw drinking water from areas in aquifers where conditions favor the
benign form of the metal.
"It's really difficult to study a groundwater system, because
there are so many variables," she said. "But I
feel that what
I'm doing will be enough to get an idea of what is happening in the
Aromas Red Sands aquifer."
In the meantime, Gonzalez will spend a month this summer working as
a teaching assistant in UCSC's COSMOS program. The
is designed for top California high school students with an interest
in math, science, or engineering.
"We're going to teach them some tricks of the trade
and take them
out to do some water sampling," she said. "We want it to be
a positive experience for everyone, and one that will make them want
to go to college."
In Gonzalez's case, the decision to attend college wasn't an obvious
one. She and her twin sister are the only members of her family to do
so thus far. The daughter of Guatemalan immigrants,
Gonzalez was tempted
to stay near her family in Los Angeles--until she visited Santa Cruz.
"I liked the programs and the atmosphere. Everyone is helpful
and the environment is beautiful here," she said.
Although she came to Santa Cruz intending to major in
ended up with a double major in environmental studies and
combining a solid grounding in science with an understanding of the
social and policy aspects of environmental issues.
If all goes as planned, Gonzalez will get her master's degree in environmental
toxicology next year. In the long run, she would like a job that involves
facilitating communication between scientists and policy makers.
This article is part of Profiles in Excellence, an ongoing
series highlighting the outstanding educational opportunities and achievements
of UCSC students and graduates. Other profiles are posted on the Profiles
in Excellence web
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