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Even fewer have been thoroughly studied, says Marisol Sepulveda, a Purdue ecotoxicologist, who develops new tools to measure the effects of such contaminants on fish and wildlife.
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| A 2001 government survey found manmade chemicals like ibuprofen, blood pressure medication, and nanoparticles in 80 percent of the streams and rivers sampled nationwide. Many of these contaminants - in addition to some only recently manufactured and discovered in surface waters - are not monitored at water treatment plants. |
Proceed with caution
"There is a real reason for concern," says Sepulveda, an assistant professor of forestry and natural resources. "Many of these chemicals harm us, as well as fish and wildlife."
Flame-retardants, for example, have been shown to bioaccumulate in fish. Like other persistent pollutants, they tend to become more concentrated as they work their way up the food chain. "These things act quite similarly to poly-chlorinated biphenyls, or PCBs, which were banned decades ago," she says.
Sepulveda and ABE professor Marshall Porterfield developed a tiny fiber optic probe that measures levels of oxygen use in fish embryos to monitor their health. These days-old eggs are very sensitive to stress caused by abnormal conditions or pollutants; the technology could be developed as a sentinel against water contamination in the future, she says.
She also studies endocrine disruptors, a broad chemical class that includes the estrogen-like byproducts of birth control pills. Studies have shown these wastes to be capable of affecting the sexual development of fish populations. "I look at the cellular, tiny level, but I realize that the things I do are important to understanding and assessing watersheds," she explains. "I think there is a growing realization that we must address concerns at this level. If we don't, we will all suffer for it."
Sepulveda also teamed up with agronomy professor Linda Lee to examine the impact of steroid hormones that leave concentrated animal feeding operations, or CAFOs. Lee searches out management methods to reduce run-off of anabolic steroids that are injected into cattle, expelled in their manure and then spread onto fields. She wants to determine if 9-trembolone, the anabolic steroid, affects the sex ratio of fish populations, an important and largely fixed trait that may be disrupted by the hormone.
Preliminary data show steroid hormones can reach nearby surface water approximately two weeks after manure application, a surprising finding, according to Lee. "In the lab, these hormones degrade within a matter of hours," she says. "We didn't expect to find it, but at least it wasn't there in levels high enough to be too concerned." However, much work remains before she and Sepulveda draw a conclusion on that front, Lee says.
It's about the people
Even the best research cannot affect change by itself. Forestry and natural resources assistant professor Linda Prokopy examines people's attitudes toward watersheds and water quality in order to figure out how to best target outreach material and education efforts. She co-leads a U.S. Department of Agriculture study of six Midwestern states to develop "social indicators" to better understand attitudes and people's willingness to change behaviors. She also partners with agronomy professor Ron Turco, ABE professor Jane Frankenberger and agricultural economics professor Jerry Shively to better understand the acceptability and impact of conservation practices on water quality among landowners in the Indianapolis-area Eagle Creek watershed.
"Ultimately, it's about people," Prokopy says. "This is a piece that's often missing. You can know all of the science—we know that buffer strips, rain gardens and better agricultural practices all help—but without getting people's cooperation, you can't improve water quality."
Prokopy explains that people's behaviors are determined by four primary factors—awareness, attitudes, constraints and capacity. By understanding these factors, policymakers, watershed leaders and educators can give citizens the incentive and resources to pursue more sustainable management methods.
Leaving our legacy
The discoveries made by Purdue researchers may begin to have an immediate effect on our water quality. Cleaner water today may benefit future generations more than we realize. By comparing land-use trends in the past with today's water quality, Bryan Pijanowski, associate professor of forestry and natural resources, found a "legacy" effect, where past pollution can remain in groundwater and enter streams and rivers up to 100 years later. "We have to think about what kind of world we want to leave our grandchildren," he says.
Send comments to agricultures.magazine@purdue.edu
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