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Support for Study of Pathogens in Soils

New Way to Track Microbial Pathogens in Soils Gains U.S.D.A. Support

Sharon Walker is one of three scientists whose research can help protect drinking water supplies by more accurately tracking pathogens through soils.

(May 9, 2006)

Sharon Walker

Sharon Walker

RIVERSIDE, Calif. — — UC Riverside is in a U.S. Department of Agriculture-funded partnership to develop better ways to track microbial pathogens from agricultural waste as they make their way through soil. The new approach may help protect drinking water supplies from contamination.

The UC Riverside scientist involved in the research is Assistant Professor of Chemical and Environmental Engineering, Sharon Walker, who is also the John Babbage Chair in Environmental Engineering at the Bourns College of Engineering. She will work with colleagues Scott Bradford of the USDA Salinity Lab on the UCR campus and Bill Johnson, a professor of geology and geophysics at the University of Utah, will share the three-year grant of about $380,000. The award will fund lab equipment, experimental costs, two Ph.D. students at UCR and another at the University of Utah.

The approach will probe the physical forces and chemical interactions which control the underground transport of pathogens as they interact both with other particles and the porous structure of the sediment. This study will be carried out through systematic micro- and macro- scale laboratory experimentation, and will ultimately lead to the development of a model that will better predict how pathogens will travel through soils.

“This work is applicable wherever there are agricultural deposits of wastes that could affect underground water sources,” Walker said. “If you can predict the movement of these pathogens, then you can better manage the containment of the waste and develop techniques to deal with any problems these pathogens may cause.”

By doing experiments and developing theoretical models, the researchers hope to establish a clear understanding and an ability to predict the physical and chemical forces that control pathogen movement through porous materials such as soils, according to the project summary. The research is designed to improve the ability of scientists and program managers at the USDA to predict the fate of these microorganisms so they can better shield underground water supplies from contamination.

“This research touches on issues that affect the nation wherever you have high-density agriculture such as feed lots, hog farms and stock yards and wherever the practice of fertilizer application or sewage sludge to enrich the soil is carried out,” Walker said. “Locally, the waste management practices of large dairy farms could be affected by this type of research as we ultimately determine how such agricultural sources may affect groundwater and watershed quality.”

The University of California, Riverside ( is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment has exceeded 21,000 students. The campus opened a medical school in 2013 and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Center. The campus has an annual statewide economic impact of more than $1 billion.

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