Superfund Scholarship Essays

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August 14, 2017

Probiotics help poplar trees clean up Superfund sites

Trees have the ability to capture and remove pollutants from the soil and degrade them through natural processes in the plant. It’s a feat of nature companies have used to help clean up polluted sites, though only in small-scale projects.

Now, a probiotic bacteria for trees can boost the speed and effectiveness of this natural cycle, providing a microbial partner to help protect trees from the toxic effects of the pollutants and break down the toxic pollutants plants bring in from contaminated groundwater.

Trees growing on the Silicon Valley test site at the start of their third season. The second and fourth trees (from left) have been given microbes and are growing faster than the poplars with no microbes (first and third trees, from left).Michael Blaylock/Edenspace Systems Corporation

Researchers from the University of Washington and several small companies have conducted the first large-scale experiment on a Superfund site using poplar trees fortified with a probiotic — or natural microbe — to clean up groundwater contaminated with trichloroethylene (TCE), a common pollutant found in industrial areas that is harmful to humans when ingested through water or inhaled from the air. Their results were published in final form Aug. 11 in the journal Environmental Science & Technology.

The successful field trial could be a game changer to quickly and effectively clean up Superfund sites around the country and polluted sites abroad that have high levels of TCE, the authors say.

“These results open the door,” said corresponding author Sharon Doty, a UW professor in the School of Environmental and Forest Sciences. “We have known about this process for a long time from our laboratory research, but it hasn’t been used in practice because there were no field results. Now, engineering companies can start using this in real life.”

Contaminated sites containing TCE and other pollutants can be expensive to clean up when using engineering methods such as excavating or pumping toxic pollutants from underground. As a result, many sites sit untreated. This new method allows contaminated sites to be dealt with more effectively, often at lower costs, promoting human health.

Doty’s lab worked to find the best microbe strain that could effectively break down TCE and boost tree growth. Jun Won Kang, a former UW graduate student, had obtained poplar wood from a site in the Midwest where trees were already growing in TCE-contaminated soil. After grinding down small samples of the trees and isolating over a hundred different microbes, each strain was then placed in a flask containing high levels of TCE.

The microbe that ultimately was selected eliminated nearly all of the TCE in its flask. The researchers had a clear winner.

“The poplar at the older site in the Midwest selected for the best microbes to help it do its job,” Doty explained. “We took advantage of that natural selection process. We just had to find the best ones that the plant already chose.”

The pollutant TCE has been used widely as a degreaser and a solvent in industrial manufacturing sites across the country. The U.S. Environmental Protection Agency cites TCE as one of the most common pollutants in soil or water, and it is present in more than 1,000 sites the agency lists as priorities for cleanup. TCE is a known carcinogen to humans, affecting the liver and even transferring the toxic pollutant to nursing babies through mothers’ breastmilk.

Given the prevalence and toxicity of TCE, the researchers used the chemical to test the ability of poplar trees infused with microbes to clean up groundwater in the Middlefield-Ellis-Whisman Superfund research area in California’s Silicon Valley after it had subsequently flowed into the NASA Research Park at NASA’s Ames Research Center. At NASA Ames, in coordination with NASA Ames’ Environmental Division, the researchers planted rows of young poplar trees — some inoculated with the specific microbe, and others without — on a field above a known groundwater plume contaminated with TCE.

After only a year, the trees given the microbe were bigger and healthier than the poplars with no special treatment. After three years, the inoculated trees were still more robust, and a sample of tree trunks revealed greatly reduced levels of TCE inside the trees.

The darker, taller poplar trees shown at the test site at the end of their third season were inoculated with microbes, while the shorter, lighter-green trees (center row) were not given the bacteria.John Freeman/Intrinsyx Technologies Corporation

When trees take up and degrade chemicals, called phytoremediation, it often comes at the expense of their own health. This manifests as stunted growth, yellow leaves, withering brown leaves and branches, and sometimes death as the pollutant hampers the tree’s ability to survive. But when the microbe selected specifically to deal with TCE is introduced, the trees destroyed the TCE — and experienced more robust growth and increased survival rates, clear benefits of the probiotic.

“The real goal is to try to improve performance,” said co-author Michael Blaylock, president and CEO of Edenspace Systems Corporation in Virginia. “If we have something that speeds up and improves performance and makes it so the trees can grow better, that’s really what we were trying to accomplish with this project.”

Additionally, the researchers found that groundwater samples taken directly downstream from the test site showed much lower levels of the pollutant, compared with higher levels up-gradient from the testing area. They also found evidence of increased chloride in the soil around the poplar roots, a harmless, naturally occurring element and byproduct of TCE as it is degraded by the bacteria inside trees.

A number of organizations have expressed interest in using this technology, said co-author John Freeman, chief science officer for Intrinsyx Technologies Corporation based at NASA’s Research Park. And landowners hampered by the high costs associated with traditional clean-up methods are starting to use the technology.

“This has the potential to make a huge impact on a lot of legacy sites where you have contaminated groundwater issues, including TCE, and where funding is currently less available,” Freeman said. “This is definitely a big cost savings to everyone involved. It’s a real win-win situation because it’s green, it’s long-term sustainable, publicly acceptable and it’s solar powered by the trees themselves.”

Other co-authors are Christopher Cohu of Phytoremediation and Phytomining Consultants United; Joel Burken of Missouri University of Science and Technology; Andrea Firrincieli of Tuscia University in Italy; Andrew Simon of Edenspace Systems Corporation; Zareen Khan of the UW; Jud Isebrands of Environmental Forestry Consultants; and Joseph Lukas of Earth Resources Technology.

The work was funded by the National Institutes of Health through a Small Business Innovation Research grant. Support for Doty’s research was also provided by the Byron and Alice Lockwood Foundation.


For more information, contact Doty at or 206-616-6255; Blaylock at or 703-961-8700; and Freeman at or 650-210-9219.

NIH grant: R44ES020099

Tag(s): biology • College of the Environment • pollution • School of Environmental and Forest Sciences • Sharon Doty

The Udall Scholarship honors Morris K. Udall, an Arizona Congressman who authored legislation to protect wilderness areas and demonstrated commitment to the Native American and Alaska Native populations. Sophomores and juniors are eligible for the scholarship, which covers educational expenses for one year up to a maximum of $5,000. Udall Scholars come from various fields, ranging from environmental science to engineering to political science, and share in common a commitment to preserving or improving the environment. Udall Scholarships also include special categories for nominees who are Native American or Alaska Native with a commitment to the areas of tribal policy and health care.

The Udall Scholarship Selection Criteria

Udall Scholarship applications are reviewed by at least two readers, ranging from professors of environmental science to scholarship directors to representatives from the EPA. Four principal categories are used to rank each applicant:

  • commitment to the environment, health care, or tribal public policy;
  • academic achievements;
  • nominee’s personal essay;
  • personal characteristics as revealed by such evidence as volunteerism and testimonials in letters of reference.

Answering the Udall Application Essay Questions

The Udall application is extensive, including short essays written in response to a series of questions. These questions invite detail in such areas as your professional aspirations, career goals, research experience, leadership, personal motivation, and service, and there’s even an open-ended question asking what additional information you wish to share. In answering these questions, former Udall applicants have described active membership in professional service organizations, a spring break Habitat for Humanity project, a life-changing semester of study in Ecuador, and a project using bird counts as a marker to assess the biological integrity of a local landscape. To answer the open-ended question, which the selection committee uses to sometimes award discretionary points, former applicants have emphasized an interest in environmental education outreach, discussed their role as the first member of their family to attend college, or noted their struggles as a single parent on financial aid.

Most important in answering these application questions is that you read the questions carefully to discern the desired criteria, that you use specifics and avoid unnecessary redundancy with other parts of the application, and that you avoid leaving any of the questions blank or providing answers that are out of proportion to your other answers in length or intent. Seek a balanced, efficient presentation.

Evaluation of Two Sample Sets of Udall Application Materials

The two sample sets of Udall application materials in the pdf below are richly detailed, with both writers thoroughly discussing research and field experiences. In discussing his environmental commitment, the first writer, an environmental engineering student, focuses on a field trip to a Superfund site where he witnessed remediation in action, while the second writer, studying mathematics and ecology, discusses a course she is taking on environmental issues in South Africa and a sailing adventure in the Florida Keys. Of note in the first writer’s essay is his creative answer to question #4, about leadership in his campus community, where he discusses his participation in an outreach service project. The first writer was put forth as a finalist but did not receive a Udall. The second writer did receive a scholarship, after winning honorable mention in the previous year.

The final application question is especially challenging, requiring you to compose an 800-word essay discussing Udall’s ideas and connect them to your own interests. Through the detail of the two samples, we sense that these writers are genuine rather than simply parroting back answers they anticipate the committee wants to hear, and that they studied Udall’s work carefully to inform their essays. The first writer focuses on Udall’s contributions to “the philosophical evolution of the environmental movement,” while the second writer takes the gutsy approach of discussing legislation that Udall fought hard for but later came to regret because of some of its impacts. This writer also draws an interesting case for simpatico views she has with Udall regarding her current environmental project.

Click here to download a pdf of two sets of Udall application essays by former students.


To apply for the Udall Scholarship, you must start the process online, where you’ll find everything from application materials to a video featuring former Udall winners.

Visit the Morris K. Udall Scholarship website.

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